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Background: Chlamydia trachomatis (C. trachomatis) infection has been implicated in various cancers, yet its association with breast cancer remains unexplored. This infection triggers a cascade of immune responses primarily regulated by Interleukins-12 (IL-12). Thus, the objective of this case-control study was to investigate the link between C. trachomatis infection and breast cancer risk, as well as the modification effect of IL-12., Methods: We assessed IgG levels against C. trachomatis in serum of 1,121 women with breast cancer (861 with estrogen receptor-positive (ER+) and 260 with estrogen receptor-negative (ER-) tumors) and 400 controls in Guangzhou, China. Logistic regression models were applied to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) for breast cancer risk in association with C. trachomatis infection. The interaction between C. trachomatis infection and IL-12 on breast cancer risk was estimated by the product terms in the logistic regression models., Results: Seropositivity of C. trachomatis IgG showed a slight association with an increased risk of breast cancer (OR = 1.20; 95% CI: 0.86∼1.78). This association was more pronounced among women with a higher (OR = 5.82; 95% CI: 1.31∼25.94) than a lower (OR = 0.73; 95% CI: 0.41∼1.30) level of IL-12, with a statistically significant interaction observed (P interaction = 0.013). In addition, C. trachomatis IgG seropositivity was related to an increased risk of breast cancer among PR+ patients (OR = 1.53; 95% CI: 1.04∼2.23)., Conclusions: C. trachomatis infection may contribute to the development of hormone-responsive breast cancer in women with high levels of IL-12. Further studies are needed to uncover the underlying mechanisms., Competing Interests: Disclosure The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Chlamydia and gonorrhea notifications are rapidly rising in men who have sex with men (MSM). Currently, there are limited data on the prevalence of chlamydia and gonorrhea across various anatomical sites. Our study aimed to explore the prevalence, association and changing trends of urethral and rectal chlamydia and gonorrhea among MSM in Guangdong Province, China., Methods: We analyzed data among MSM attending sexually transmitted infections (STI) clinics in the Guangdong governmental sentinel network between 2018 and 2022. Chi-square tests were used to compare the difference, Join-point regressions for analyzing changing trends, and multivariate logistic regressions for examining associated factors., Results: We included 4856 men in the analysis. Rectal chlamydia significantly increased from 13.8% to 26.4% over the past 5 years (average annual percentage change [AAPC] 19.2%, 95%CI 1.0-40.6, p = 0.043). After adjusting for covariates, chlamydia infection positively associated with main venue used to seek sexual partners (aOR = 2.31, 95%CI 1.17-4.55), having regular sexual partners in the past 6 months (aOR = 3.32, 95%CI 1.95-5.64), receiving HIV counselling and testing services (aOR = 2.94, 95%CI 1.67-5.17), receiving peer education (aOR = 1.80, 95%CI 1.14-2.83), infection with syphilis (aOR = 2.02, 95%CI 1.02-4.01) and infection with gonorrhea (aOR 7.04, 95% CI 3.01-16.48). Gonorrhea infection positively associated with having regular sexual partners in the past 6 months (aOR = 3.48.95%CI 1.16-10.49), and infection with chlamydia (aOR 7.03, 95% CI 2.99-16.51)., Conclusions: To conclude, our findings reveal a high prevalence of chlamydia infections among MSM, particularly in the rectal area. Comprehensive chlamydia and gonorrhea health services are necessary for MSM to improve sexual health., (© 2024. The Author(s).)

Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT), Ureaplasma urealyticum (UU) are the common sexually transmitted pathogens and lead to genital diseases, highly prevalent all around the world. The objective of this study was to analyze the prevalence of NG, CT and UU among outpatients in central China. A total of 2186 urogenital swabs were collected from the patients and the NG, CT and UU pathogens were testing with RT-PCR method, meanwhile the medical records were obtained from the hospital information system. The overall infection rates of NG, CT and UU were 4.57 %, 6.63 % and 48.81 % respectively, showed the prevalence of UU was higher than NG and CT. The younger people had the highest infection rate of NG (10.81 %), CT (20.54 %) and UU (54.59 %). Single infection (89.09 %) was significant higher than co-infection (10.91 %), and the CT-UU co-infection was the prominent pattern (66.41 %). There were an obvious sex difference, the prevalence of NG and CT were significant higher in male, whereas UU was higher in female. Our study could contributed a better understanding of the prevalence of NG, CT and UU, facilitating to the development of effective screening, prevention and treatment policies., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations., (Copyright © 2024. Published by Elsevier Inc.)

Background: Sexually transmitted infections (STIs) increase gradually and have become a public health problem in the world. UU, CT, NG, and MG are four common STI pathogens. Our retrospective study analyzed the clinical situation and the laboratory data of patients infected with the four pathogens. The prevalence of the four pathogens, detected in urine and genital tract secretion, was studied in Hangzhou, China., Methods: A total of 3,168 male and female patients were randomly selected from February 2023 to February 2024. Urine and genital secretions were collected, and four STI pathogens were controlled for detection. Data were collected from the hospital's electronic medical records, and SPSS 25.0 software was used to perform a statistical analysis., Results: Among 3,168 patients, a total of 1,527 were detected as positive, and the positive rate was 48.20%. The age of patients ranged from 13 - 98 years, with an average age of 45.6. The total of patients consisted of 2,191 males and 977 females, which had a significant difference (p < 0.05). Specimens were mainly collected from the Department of Dermatovenerology, Urological Surgery, Obstetrics and Gynecology, and so on. The positive rate was statistically different between male and female patients (p < 0.05). Single infection performed a main role and accounted for 79.57% of all of the positive patients. In the ≤ 20 age group, the positive rate was the highest and was as high as 77.65%. In detail, single infection caused by UU dominated, especially in the 21 - 30 age group. Double infection caused by UU and CT and triple infection caused by UU, CT, and NG were the majority, both especially in the 21 - 30 age group. There were significant differences in the positive rates in the different age groups and in the four pathogens (p < 0.05). Quadruple infection was very rare and had only been detected in one patient., Conclusions: The prevalence of the four pathogens in Hangzhou was different from other regions. More male than female patients, more single than multiple infections, and more single and multiple infections occurring in young people were the features in Hangzhou. The study would provide reference for prevention, diagnosis, and treatment of STI.

Introduction: Chlamydia trachomatis infection can cause a significant disease burden in high-risk populations. This study aimed to assess the overall prevalence of C. trachomatis infection, and determine the long-term trends and geographic distribution of this infection among female sex workers (FSWs) and men who have sex with men (MSM) in China., Methods: The PubMed, Web of Science, CNKI, Wanfang Data and VIP databases were searched from 1 January 1990 through 30 April 2023. Publications in which C. trachomatis infection was detected using nucleic acid amplification tests (NAATs) were included. The Q test and I 2 statistics were used to assess the heterogeneity between studies. A random-effect model was used to estimate the pooled prevalence of C. trachomatis infection. Subgroup, meta-regression, and sensitivity analyses were performed to explore the sources of heterogeneity. Publication bias was evaluated using Egger's test. Trend analysis of the prevalence was performed using the Jonckheere-Terpstra trend test method., Results: Sixty-one studies were eligible for inclusion (including 38 for FSWs and 23 for MSM). The pooled prevalence of C. trachomatis infection was 19.5% (95% CI: 16.4, 23.0) among FSWs and 12.7% (95% CI: 9.2, 17.7) in the rectum, 6.4% (95% CI: 5.3, 7.8) in the urethra and 1.3% (95% CI: 0.8, 2.1) in the oropharynx from MSM in China. The subgroup analyses showed that the sample size, study period, study region, specimen collection type, molecular diagnosis method, and recruitment site could explain some heterogeneity among studies of FSWs, and the publication language, study period, study region, molecular diagnosis method, and specimen collection anatomical site could explain some heterogeneity among studies of MSM. From 1998 to 2004, 2005 to 2009, 2010 to 2015, and 2016 to 2021, the pooled prevalence of C. trachomatis infection among FSWs were 30.3%, 19.9%, 21.4%, and 11.3%, respectively. For MSM, the pooled prevalence from 2003 to 2009, 2010 to 2015, and 2016 to 2022 were 7.8%, 4.7%, and 6.5%, respectively. However, no overall decline in the prevalence of C. trachomatis infection was observed among FSWs (z = -1.51, P = 0.13) or MSM (z = -0.71, P = 0.48) in China., Conclusions: The prevalence of C. trachomatis infection was high in these two high-risk populations in China. The findings of this study provide evidence for the formulation of effective surveillance and screening strategies for the prevention and control of C. trachomatis infection among these two specific populations., (© 2024. The Author(s).)

Background: Rectal Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections among men who have sex with men (MSM) are escalating public health concerns. This study aimed to explore (1) the reliability of self-reported sexual positioning as an indicator for rectal CT and NG screening, and (2) factors associated with rectal CT and NG infections in Shenzhen, China., Methods: A cross-sectional study was conducted in 2 settings in Shenzhen, China, from April 1, 2021, to March 31, 2022. Data on sociodemographic characteristics, sexual behaviors, and basic CT knowledge were collected. Urine and self-collected rectal swabs were collected for CT and NG testing., Results: In total, 195 MSM participated in the study, and 5.1% tested positive for urogenital CT, 29.2% for rectal CT, 1.0% for urogenital NG, and 8.2% for rectal NG. Among those who reported exclusively insertive anal sex, 69.2% of CT infections and 85.7% of NG infections would have remained undetected with urine testing alone. Risk factors for rectal CT infection included engaging in both insertive and receptive anal sex, with a significant association found for coinfection with rectal NG., Conclusions: Self-reported sexual positioning was found to be an unreliable indicator for CT and NG screening, as a substantial proportion of infections would have remained undetected. The findings suggest that CT and NG screening in China should be offered to all MSM regardless of self-reported sexual positioning, and that the dual CT/NG testing is recommended., Competing Interests: Conflict of Interest and Sources of Funding: The authors declare no conflict of interest. This study was supported by the Sanming Project of Medicine in Shenzhen (No. SZSM201611077)., (Copyright © 2024 American Sexually Transmitted Diseases Association. All rights reserved.)

Background: Men who have sex with men (MSM) face significant risks of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) infection. Nevertheless, only limited studies have looked into the site-specific infection and clearance of CT/NG. In order to prevent transmission, it is essential to understand the underlying factors that drive infection and spontaneous clearance., Methods: A 12-week cohort study examined the association between CT/NG infection, self-clearance, and sexual behaviors among MSM. The Willingness Service recruited participants who completed weekly questionnaires and provided urine, throat, and rectal swab samples., Results: The study involved 151 men, in which 51 (33.8%) were diagnosed with CT/NG infection during the study period. HIV (OR = 11.31), kissing (OR = 1.59), receptive oral sex (OR = 36.64), and insertive anal sex (OR = 19.73) constituted significant risk factors. 100% condom use (OR = 5.78) and antibiotic (OR = 7.53) were more likely to cause spontaneous clearance., Discussion: MSM may engage in riskier sexual behaviors due to insufficient knowledge and awareness of STI prevention, leading to increased susceptibility to NG/CT. It is crucial to concentrate on enhancing health education for MSM., Conclusion: This study found that the rectum was the most prevalent site of CT/NG and sexual behavior can influence the infection. Additionally, the appropriate use of antibiotics and consistent condom use may contribute to clear spontaneously., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer PZ declared a shared affiliation with the author WT to the handling editor at the time of review., (Copyright © 2024 Lyu, Tang, Feng, Hu, Wang, Zhou, Huang, Li, Zhu, He, Tang, Zhou and Zhang.)

Background: Chlamydia infection data in pigs in Hunan province, southern China. Therefore, in order to evaluate the seroprevalence and identify risk factors associated with chlamydia infection data in pigs in Hunan province, southern China. Therefore, in order to evaluate the seroprevalence and identify risk factors associated with Chlamydia infection in pigs within this region, a comprehensive study was conducted. Methods: A total of 3848 serum samples were collected from pigs (from farmers and companies) between May 2017 and August 2018. The presence of specific antibodies against Chlamydia was determined through the employment of the indirect hemagglutination assay (IHA). Results: The overall seroprevalence of Chlamydia was determined to be 26.90% (1038/3848, 95% confidence interval: 25.60-28.40). By employing statistical analysis using SPSS software ( p  < 0.05), factors such as altitude, sampling regions, and rearing systems of pigs were identified as potential risk factors for Chlamydia infection. Conclusion: in pigs within the mountainous region of Hunan province, southern China, thereby highlighting a potential risk to human health. These results underscore the need for proactive measures and targeted interventions to mitigate the transmission of Chlamydia in porcine populations, safeguarding both animal welfare and public health.Chlamydia in pigs within the mountainous region of Hunan province, southern China, thereby highlighting a potential risk to human health. These results underscore the need for proactive measures and targeted interventions to mitigate the transmission of Chlamydia in porcine populations, safeguarding both animal welfare and public health.

Background: Female sex workers (FSW) are particularly vulnerable to chlamydia and gonorrhea infections. However, there were few studies that detail the evolving patterns of chlamydia and gonorrhea among Chinese FSW. Therefore, our study endeavors to assess the prevalence of chlamydia and gonorrhea epidemics within FSW, investigate their changing trends and scrutinize associated factors., Methods: In 2019, China instituted a sentinel surveillance network focused on FSW in Guangdong Province. This network conducted an annual serial cross-sectional survey spanning from April to August. All analyses are predicated on surveillance data accumulated between 2019 and 2022., Results: The prevalence of chlamydia increased from 10.1 to 12.3%, exhibiting an annual percentage shift of 6.8%. Conversely, the prevalence of gonorrhea dwindled from 2.0 to 1.3%, marking an annual percentage decline of 13.4% (P < 0.001). After adjusting for covariates, chlamydia exhibited associations with having household registration in other provinces (adjusted odds ratio (aOR = 0.55)), displaying symptoms of sexually transmitted infections (STIs) (aOR = 1.65) and infected with gonorrhea (aOR = 5.68). In parallel, gonorrhea demonstrated associations with providing oral sex to clients (aOR = 3.74), manifesting STIs symptoms (aOR = 4.27) and those infected with chlamydia (aOR = 5.43)., Conclusions: Our observations underscore the imperative to implement a comprehensive intervention strategy concentrating on chlamydia, while simultaneously fortifying endeavors to expand the scope of gonorrhea prevention services., (© The Author(s) 2023. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Chlamydia Trachomatis (CT) is among the most prevalent sexually transmitted diseases (STDs) globally. According to the World Health Organization, more than 131 million people get infected with CT annually. CT is usually transmitted via sexual contact or perinatal exposure and can result in severe long-term complications. In developing nations, particularly, the prevention and control of CT is challenging. Hence, this study will explore the feedback mechanisms of chlamydia prevention and control, as well as identify the essential factors affecting the control and prevention of this infection in China., Methods: Our study will employ a mixed-methods research design that encompasses both qualitative and quantitative methods. Firstly, we will develop a causal loop diagram (CLD) based on the literature review and optimize it via in-depth interviews with stakeholders. Additionally, we will utilize a quantitative method called MICMAC(Impact Matrix Cross-Reference Multiplication Applied to a Classification tool) to obtain consensus among different stakeholders and pinpoint the key information. Next, the CLD will be transformed into a system dynamics model (SDM) to evaluate the feedback mechanisms within the CLD. The causality in the CLD will be modeled using mathematical equations, which facilitate the transformation into an SDM. As such, we will be able to analyze the dynamic behavior of the system and its response to different decisions., Discussion: Our study offers a systematic perspective on the control and prevention of chlamydia infection through system dynamics modeling, examining the dynamic properties and background factors of the system. The creation of the CLD affords stakeholders the chance to comprehend the functionality of their relationships and improve cooperation. Consequently, by evaluating the outcomes of these simulations, it will be possible to analyze and determine potential interventions and their effects on chlamydia infections. This modeling approach can help us gain insight into the dynamic characteristics of the system, evaluate the potential outcomes of different decisions, and design control strategies to either stabilize the system or adjust its behavior., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Objectives: This systematic review was conducted to estimate the respective prevalence of gonorrhea among two high-risk populations in China and determine the epidemiological features of gonorrhea in them., Study Design: Systematic review., Methods: PubMed, Web of Science, China National Knowledge Infrastructure, and Wanfang databases were searched to identify studies published between January 1, 1990, and October 31, 2022, with gonorrhea prevalence tested by polymerase chain reaction among female sex workers (FSWs) and men who have sex with men (MSM). Meta-regression and subgroup analyses were used to investigate potential factors of heterogeneity across studies. Trend analysis of prevalence was conducted by the Jonckheere-Terpstra method., Results: We identified 88 prevalence data points from 49 studies in China, with 30,853 participants of FSWs and 5523 participants of MSM. Pooled prevalence of gonorrhea among FSWs and MSM were 6.9% (95% confidence interval: 4.6-9.7%) and 2.5% (95% confidence interval: 1.5-3.7%), respectively. The subgroup analyses showed there were period, regional, and specimen collection methods diversities among FSWs, and diversities of the regions and specimen collection anatomical sites were found among MSM, in which the prevalence of rectum and pharynx was significantly higher than the urethra. A decreasing trend in the prevalence of gonorrhea was seen among FSWs (z = -4.03) from 1999 to 2021, not found for MSM in China., Conclusion: The prevalence of gonorrhea is high in two high-risk groups in China, with extragenital infections requiring particular attention. The findings of this study will provide evidence to formulate national policy and guidance for gonorrhea prevention and control., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: This study evaluated the clinical laboratory capacity for the diagnosis of Chlamydia trachomatis (CT) in China to provide recommendations to improve the diagnostic capacity and quality of this clinically important sexually transmitted disease., Methods: An electronic questionnaire-based cross-sectional, survey study was conducted by the National Center for STD Control among different types of healthcare facilities in China from July to December 2021., Results: The surveyed laboratory facilities were located in 332 cities in 31 provinces in China. A total of 4640 records from clinical laboratories were included in the data set for the final analysis. Less than half of the laboratories (41.6% [1931 of 4640]) performed the CT diagnostic test; of these, 721 laboratories (15.5% [721 of 4640]) carried out nucleic acid amplification test (NAAT) methods, and 1318 laboratories (28.4% [1318 of 4640]) performed antigen-based immunochromatographic assays. Most laboratories were equipped with biological safety cabinets (93.7% [4348 of 4640]), 49.2% (2283 of 4640) were equipped with fully automated nucleic acid extractors, and 55.2% (2560 of 4640) were equipped with polymerase chain reaction amplification instruments. The laboratories from Southern China or third-class hospitals (i.e., the highest rated hospitals) had the highest proportion using NAATs to diagnose CT among the surveyed health facilities., Conclusions: Advancing laboratories to use NAAT to detect CT should be phased step-by-step by different areas and levels of hospitals according to the current situation., Competing Interests: Conflict of Interest and Sources of Funding: None declared., (Copyright © 2023 American Sexually Transmitted Diseases Association. All rights reserved.)

Background: Gonorrhea and chlamydia are the most common sexually transmitted diseases (STDs) among men who have sex with men (MSM) in China. Previous studies have shown pay-it-forward (PIF) interventions to be associated with a substantial increase in gonorrhea and chlamydia test uptake compared to standard-of-care. We propose a 'pay-it-forward' gonorrhea and chlamydia testing randomized controlled trial (PIONEER). The trial would evaluate the effectiveness of two pay-it-forward strategies in promoting testing uptake compared to the standard of care (in which men pay for their tests out-of-pocket) among MSM and male STD patients in China., Methods: PIONEER will be a three-armed, pragmatic cluster randomized controlled trial (RCT), conducted across 12 clinics (six MSM-led and six public STD clinics) to compare the effectiveness of three implementation strategies. Each facility will be randomized to a standard pay-it-forward intervention of gonorrhea/ chlamydia testing with minimal encouragement for testing, a community-engaged pay-it-forward arm, or a control arm where men pay for their tests out-of-pockets. The primary outcome will be dual gonorrhea/chlamydia test uptake. Secondary outcomes will include syphilis testing, amount donated in pay-it-forward, number of positive gonorrhea and chlamydia tests, and measures of antimicrobial resistance. A sequential transformative mixed methods design will be used to evaluate the implementation process in type 2 effectiveness-implementation hybrid design. Data sources will include survey on acceptability, and feelings and attitudes towards the interventions among participants; testing and treatment uptake data from clinic records, WeChat records, and qualitative data to gain insights into men's perceptions and attitudes towards the pay-it-forward, mechanisms driving uptake, and donating behaviors. Implementers and organizers will be interviewed about fidelity and adherence to protocol, sustainability of pay-it-forward intervention, and barriers and facilitators of implementing the intervention., Discussion: PIONEER will substantially increase gonorrhea/chlamydia testing among MSM in China, providing an innovative and new financial mechanism to sustain STD screening among sexual minorities in low- and middle-income countries. This study will answer compelling scientific questions about how best to implement pay-it-forward and the individual and organizational characteristics that moderate it., Trial Registration: The study with identification number NCT05723263 has been registered on clinicaltrials.gov/., (© 2023. The Author(s).)

Background: Actively screening for Chlamydia trachomatis (CT) is important for young people because of a high prevalence of asymptomatic infection in this population. This study aimed to investigate knowledge on CT and preference to the screening services for CT among young students in China., Methods: From June to July 2022, a web-based questionnaire survey was conducted to collect information on sociodemographic characteristics, sexual behaviors, knowledge of CT, previous testing for CT, and preference to platform of testing for CT among Chinese young students. An online home-based self-sampling test (HBSST) service was offered free of charge if the participant was willing to be tested for CT. Statistical analyses included descriptive analysis, χ 2 test, and multivariable logistic regression., Results: Of 520 participants, 419 (80.6%) were aged between 16 and 24 years, 235 (45.2%) reported having sexual experience in the past, and 27 (5.2%) being tested before for CT. Slightly higher than 10% (57/520) of students were knowledgeable about CT. About one-third (36.9%) expressed their willingness to have a testing for CT but majority of them (63.1%) preferred to a free testing. Having sexual experience was significantly associated with the willingness to take the HBSST service (adjusted odds ratio, 2.96; 95% confidence interval, 1.92-4.58). A total of 139 (26.7%) participants requested the HBSST service online and 43.2% (60/139) returned the specimen for testing, in which 2 positives (3.3%) were found., Conclusions: The knowledge on CT and the previous uptake or current willingness to have a testing for CT was low among Chinese young students., Competing Interests: Conflict of Interest: None declared., (Copyright © 2022 American Sexually Transmitted Diseases Association. All rights reserved.)

Background: Many studies have focused on the distribution and specific clinical symptoms caused by Chlamydia trachomatis . Still, relatively few studies have focused on the associations between Chlamydia trachomatis genotypes and cervical intraepithelial lesions., Objectives: This study was conducted to determine the distribution of Chlamydia trachomatis genotypes and its associations with cervical intraepithelial lesions among women of reproductive age. The presence of other STIs coinfection was also evaluated., Method: 375 Chlamydia trachomatis positive cervical swabs collected from women of reproductive age were analyzed though molecular assay. Multivariate logistic regression analyses (covariates include contraception, gravidity (≥1), abnormal vaginal discharge, adverse pregnancy outcomes, reproductive tract symptoms and abnormal cervical cytology) were performed to evaluate the associations between Chlamydia trachomatis genotypes and cervical intraepithelial lesions and genital clinical symptoms., Results: Among 375 Chlamydia trachomatis positive cervical swabs, the prevalence of coinfection with Neisseria gonorrhoeae, Candida albicans, Trichomonas vaginitis, Vulvovaginal candidiasis , and HPV were 0.8%, 2.7%, 2.4%, 10.1% and 15.5%, respectively. 306 were genotyped successfully, and nine genotypes were identified. The most common genovar was E (25.16%, 77/306), followed by J (22.55%, 69/306), F (17%, 52/306), D (14.4%, 44/306), K (7.2%, 22/306), G (6.9%, 21/306), H (5.2%, 16/306), B (1.0%, 3/306), Ia (0.7%, 2/306). Genotype H was associated with abnormal cervical cytology [ p = 0.006, aOR = 8.16 (1.86-36.6)]. However, this study observed no association between Chlamydia trachomatis genotypes and any genital clinical symptoms., Conclusions: Chlamydia trachomatis genotype H may be a high risk factor for cervical intraepithelial lesions, which is useful for treatment and management measures for patients with cervical intraepithelial lesions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Liu, Sun, Zhang, Wu, Tian, Li, Chen and Luo.)

Background: Epidemics of sexually transmitted infections (STIs) among men who have sex with men (MSM) are major global public health concerns. This study aimed to examine the prevalence of syphilis and chlamydia trachomatis (CT) infection and associated factors among MSM in Jiangsu province, China, hoping to provide updated data for the formulation of relevant policies., Methods: A cross-sectional survey was conducted among MSM from April to July 2021 in four cities in the province. Socio-demographic characteristics and behavioral information were collected through a face-to-face questionnaire interview. Venous blood specimens were collected for HIV, hepatitis C (HCV), and syphilis testing using serological testing methods. First-void urine specimens were collected for CT and Neisseria gonorrhoeae (NG) testing using nucleic acid amplification testing (NAAT) methods. Chi-square tests were used to compare differences in syphilis and CT infection between subgroups of variables. Multivariate logistic regression analysis was used to identify factors associated with syphilis and CT infection., Results: A total of 1,087 participants were enrolled. The prevalence of HIV, HCV, syphilis, CT and NG infection were 6.6, 0.4, 6.3, 4.2, and 0.4%, respectively. MSM recruited online [adjusted odds ratio (aOR) = 2.189, P = 0.020], diagnosed with an STI in the past 12 months (aOR = 3.304, P < 0.001), and living with HIV (aOR = 4.721, P < 0.001) were more likely to have syphilis infection. MSM who were younger than 25 years (aOR = 4.286, P = 0.020), had senior high school level education (aOR = 2.521, P = 0.038), and were recruited via VCT clinics (aOR = 3.455, P = 0.001) were more likely to have CT infection., Conclusions: Our study showed a high prevalence of syphilis and chlamydia among MSM in Jiangsu province, China. STI screening, diagnosis, and treatment services promotion should be a top priority on the prevention agenda., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hu, Chen, Shi, Liu, Xu, Sun, Zhao, Zhou, Lu, Zhang, Liu and Fu.)

Background: Genital Chlamydia trachomatis (CT) is one of the most common agents of sexually transmitted infections and can cause severe disorders. This study aimed to analyse the genetic and clinical characteristics of genital CT infection among women in Guangzhou, China., Methods: From September 2020 to August 2021, a total of 8955 female patients were enrolled in this study. The presence of genital CT was detected by real-time PCR, and 273 positive samples were randomly selected for further genetic and clinical characteristics analysis., Results: The positive rate of genital CT infection was 7.5% (670/8955), with the highest rate in women aged 21-30 years. A total of 8 genotypes were identified: DH, J, K, and recombinant genotype Ba/D. The predominant genotype was J (n = 78, 28.6%), followed by E (n = 63, 23.1%), F (n = 48, 17.6%), and D (n = 38, 13.9%). Abnormal vaginal discharge (n = 165, 61.8%), cervical columnar epithelial ectopy (n = 124, 46.4%), vaginal itching (n = 77, 28.8%), and lower abdominal pain (n = 61, 22.8%) were the predominant symptoms. Additionally, genotype G infection exhibited a significantly higher rate of abnormal vaginal discharge (P = 0.03) and genotype D infection exhibited a higher white blood cell count (P = 0.01) than the other genotypes. Phylogenetic analysis revealed a total of 20 variants with 25 mutation positions and the H2 variant in four patients was first discovered in our study., Conclusions: Genotypes J, E, F, and D were the major genotypes of genital CT in Guangzhou, and they manifested as abnormal vaginal discharge, cervical columnar epithelial ectopy, vaginal itching, and lower abdominal pain. The present study provides guidance for future integrated interventions to reduce the burden of genital CT infection and accelerate the development of vaccines., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections are prevalent among men who have sex with men (MSM) in China. However, compared to syphilis and HIV, the testing rate for chlamydia and gonorrhea remains low. The purpose of this pilot study was to evaluate the feasibility for conducting rapid nucleic acid test for chlamydia and gonorrhea in MSM community-based organizations (CBO)., Method: We recruited our participants through an MSM CBO where free HV and syphilis testing were routinely provided. We collected data including social-demographic background, sexual history, chlamydia and gonorrhea testing history, and reasons for accepting this on-site rapid testing. Urine and/or anorectal swab samples were collected and tested for chlamydia and gonorrhea on-site and the testing results were delivered in about 1.5 h. Positive cases received on-site free treatment., Results: From August 2020 to October 2020, 634 MSM visited the CBO for syphilis and HIV testing and 158 (158/634, 24.9%) accepted the on-site chlamydia and gonorrhea rapid test, 135 were finally enrolled. The positive rate fo chlamydia was 16.3% (22/135) and 3.0% (4/135) for gonorrhea, respectively. Only 19.3% participants had previously undergone chlamydia and gonorrhea testing and 68.9% (93/135) participants reported that they had heard of gonorrhea, 47.4% (64/135) had heard of chlamydia. The main reason for testing was "free for charge" (66.2%), followed by "convenient, 'shorter waiting time" (45.2%) and "had high-risk sexual behavior recently" (16.3%)., Conclusions: This pilot study showed that the chlamydia and gonorrhea infection rate remains high among MSM, while the testing rate was low. On-site rapid testing is feasible and potentially preferred by MSM., (© 2022. The Author(s).)

Chlamydia bovis is a widespread infection disease caused by the mixed infection of Chlamydia psittaci , Chlamydia pecorum , Chlamydia abortus , and Chlamydia suis in cattle. Although many studies have investigated Chlamydia infection in cattle, there is no nationwide study on the prevalence of Chlamydia infection in cattle of China. We constructed the first meta-analysis to assess the infection rate and infection risk factors of Chlamydia in cattle in China, and we searched PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and VIP Chinese journal database for studies reporting Chlamydia infection in cattle from April 29, 2020. We collected a total of 563 publications from 1989 to 2019, and finally, 78 studies were eligible, which included 152,364 cattle from 27 provinces across the country. We estimated the pooled prevalence of Chlamydia in cattle was 14.2% (95% confidence interval [CI]: 12.2 to 16.4). The prevalence of bovine Chlamydia in China collected before 2000 (14.8%, 95% CI: 5.6 to 27.3) showed the highest prevalence rate. The highest prevalence was found in Central China (22.6%, 95% CI: 12.8 to 34.2). The prevalence of Chlamydia spp. between abortion cattle (39.1%, 95% CI: 24.6 to 54.6) and healthy cattle (8.3%, 95% CI: 3.1 to 15.2) showed significant variation ( p  < 0.05). In detection methods subgroup, enzyme-linked immunosorbent assay (30.5%, 95% CI: 21.5 to 40.3) showed the highest prevalence. In the age subgroup, the prevalence rate of age >1 year (16.6%, 95% CI: 12.6 to 20.9) was higher compared with age ≤1 year (9.8%, 95% CI: 6.7 to 13.3). Yaks (17.8%, 95% CI: 13.3 to 22.8) showed the highest Chlamydia prevalence among the varieties of bovine. We also estimated the potential risk factors such as feeding model, sample classification, sampling seasons, bovine gender, parity, and quality level of included studies. Our findings suggested that Chlamydia was prevalent in cattle in China. So we should pay attention to bovine Chlamydia and take necessary measures to prevent it.

Abstract: Epidemics of Chlamydia trachomatis (CT) infection among women are major global public health concerns. This study examined the prevalence of CT infection and associated factors among women attending sexually transmitted disease (STD) and gynecology clinics in Jiangsu province, China.A cross-sectional survey was conducted among women attending STD and gynecology clinics in the province during 2018 to 2019. Socio-demographic and behavioral information were collected through face-to-face questionnaire survey. Cervical swab specimens were collected to test for CT. Chi square tests were used to compare differences in CT prevalence between subgroups of characteristics. Multivariate logistic regression analysis was used to identify factors associated with CT infection.A total of 2664 participants were enrolled. The prevalence of CT infection was 16.6% (95% confidence interval: 15.0%-18.1%). Of those, CT prevalence among participants from STD clinics (19.4%) and South Jiangsu (18.5%) were higher. Female outpatients who were service personnel (adjusted odds ratio [aOR] = 1.667, P = .004) or farmers (aOR = 1.593, P = .039), lived in South Jiangsu (aOR = 1.796, P = .004), and were from STD clinics (aOR = 1.608, P = .022) were more likely to infect CT.Our study showed a high prevalence of CT infection among women attending STD and gynecology clinics in Jiangsu province, China. CT screening, surveillance and treatment promotion should therefore be of top priority on the CT prevention agenda., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Chlamydia trachomatis detection plays a crucial role in early diagnosis and treatment of C. trachomatis infection. In the current study, the capability of sexually transmitted disease (STD) laboratories to detect C. trachomatis was investigated in Guangdong, China., Methods: An external quality assessment panel, including 5 positive samples with different C. trachomatis loads and 2 negative samples was distributed to 654 participating laboratories in October 2019, and the test results were analyzed by Guangdong Central STD Laboratory. The use of various C. trachomatis detection methods in Guangdong from 2015 to 2019 was also retrospectively investigated., Results: Of the 654 participating STD laboratories, 559 (85.47%) used immune chromatographic-rapid diagnostic tests (IC-RDTs) to detect C. trachomatis in 2019, and 95 (14.53%) used nucleic acid amplification tests (NAATs). The rate of NAATs use increased approximately 4-fold from 2015 to 2019. The sensitivity of IC-RDTs decreased markedly from 97.32% to 30.89% with decreasing C. trachomatis load, whereas that of NAATs was 97.62% to 100% in all positive samples. With respect to negative samples the specificity of IC-RDTs was 97.13% to 97.30% and that of NAATs was 98.95% to 100%. Laboratories using IC-RDTs were less likely to detect C. trachomatis than those using NAATs in samples with C. trachomatis loads of 20000 copies/mL or less (P < 0.0001). Further analysis indicated no significant difference (P > 0.05) in detection rate among the 4 IC-RDT assays commonly used by the participating laboratories., Conclusions: Immune chromatographic-rapid diagnostic tests are commonly used for C. trachomatis detection by many laboratories in Guangdong, but their low sensitivity may lead to missed diagnoses. Nucleic acid amplification tests exhibit high sensitivity and specificity and should be recommended for C. trachomatis detection in STD laboratories., Competing Interests: Conflicts of Interest: None declared., (Copyright © 2020 American Sexually Transmitted Diseases Association. All rights reserved.)

Background: Female sex workers (FSW) are highly susceptible to chlamydia and gonorrhea infection. However, there is limited literature examining their testing uptake to date. This study aimed to assess the uptake and determinants of chlamydia and gonorrhea testing among FSW in Southern China., Methods: A cross-sectional study with convenience sampling was performed in five cities in Southern China. Data on socio-demographic characteristics, sexual behaviors, chlamydia and gonorrhea testing, and the utilization of health care services from participants were collected through face-to-face interviews. Univariate and multivariable logistic regressions were used to determine factors associated with chlamydia and gonorrhea testing, respectively., Results: Overall, 1207 FSWs were recruited, with the mean age of 30.7 ± 6.8 years and an average number of clients of 7.0 (4.0-10.0) per week. 65.4% participants constantly used condoms with clients during the past month. Only 7.5 and 10.4% had been tested for chlamydia and gonorrhea in the last year, respectively. Multivariable analysis indicated that FSW who worked at low tiers (adjusted Odds Ratio (aOR) = 2.36, 95%CI:1.23-10.14), had more clients in the last month (aOR = 1.03, 95%CI:1.01-1.05), used condoms consistently (aOR = 1.79, 95%CI:1.12-2.86), had STD symptoms (aOR = 4.09,95%CI:2.62-6.40), had been tested for HIV (aOR = 5.16, 95%CI:3.21-8.30) or syphilis (aOR = 6.90, 95%CI:4.21-11.22) in the last year were more likely to have chlamydia testing. In addition, FSW who had more clients in the past month (aOR = 1.02,95%CI:1.00-1.04), had STD symptoms (aOR = 3.33, 95%CI:2.03-5.46), had been tested for HIV (aOR = 3.94, 95%CI:2.34-6.65) and syphilis (aOR = 3.27, 95%CI:1.96-5.46) in the last year were more likely to have gonorrhea testing., Conclusions: The testing rates of chlamydia and gonorrhea are low among Chinese FSW. Integrating chlamydia and gonorrhea testing into HIV testing promotion programs may help bridge the gap among FSW., (© 2021. The Author(s).)

The reported prevalence of genital Chlamydia trachomatis infection (GCTI) is much lower in low-income countries than that in high-income countries. This study surveyed the prevalence of GCTI in 456 hospitals in Shandong province, China in December 2018. Among the hospitals surveyed, antigen testing, PCR testing, and either antigen or PCR testing were available in 200 (43.9%), 88 (19.3%), and 268 (58.8%) hospitals, respectively. PCR testing was more available in tertiary hospitals than in primary and secondary hospitals (χ 2 = 28.560, P = 0.000). Significant differences were observed in the availability of antigen testing (χ 2 = 15.708, P = 0.003), PCR testing (χ 2 = 22.494, P = 0.000), and either antigen or PCR testing (χ 2 = 21.729, P = 0.000) among different types of hospitals. In 2018, 1532 cases of GCTI were reported in 99 hospitals. Tertiary hospitals reported more cases than those in primary and secondary hospitals (χ 2 = 24.082, P = 0.000). The distribution of different types of hospitals that reported GCTI cases was consistent with that of hospitals that provided laboratory testing for GCTI. Antigen and PCR testing were only available in 200 (43.9%) and 88 (19.3%) hospitals, respectively. The results highlighted that the availability of laboratory testing for GCTI in Shandong province was poor, suggesting that the prevalence of GCTI in the province had been sorely underestimated.

Background: Chlamydia is common amongst the sexually active population in Hong Kong. As most cases are asymptomatic, partner notification may be helpful in controlling chlamydia. This study examined attitudes towards partner notification for chlamydia among Hong Kong Chinese youths in order to inform a culturally appropriate, patient-empowering sexual health service., Methods: Sixteen individuals (aged 20 to 31) who received a confirmed diagnosis of chlamydia within the previous twelve months of data collection were recruited from two community-based organizations between June and December 2017. Semi-structured individual interviews were conducted by a health psychologist., Results: Nine participants notified a total of eleven current and ex-partners. Seven participants did not notify their sexual partner(s). Our findings revealed how participants struggled with the discrediting sexual aspect of their infection, and how de-sexualizing the infection and selected disclosure facilitated partner notification and social acceptance. Perceived stigma regarding chlamydia however did not dissipate with their disclosure. Participants did not perceive lasting impact of chlamydia on their well-being as they thought they have much control over whether and how to disclose to their (future) partners. All participants agreed there was a pressing need to raise public awareness on this silent but highly prevalent sexually transmitted infection., Conclusions: Our findings illustrate the complex struggle behind communicating about chlamydia to one's sexual partner and how strategizing the disclosure process served to circumvent embarrassment and foster testing of sexual partners.

Toxoplasma gondii, Neospora caninum, Chlamydia and bluetongue virus (BTV) are four important pathogens which can cause reproductive loss. The present study was conducted to estimate the seroprevalence of T. gondii, N. caninum, Chlamydia and BTV in alpacas in Shanxi Province, northern China. A total of 251 serum samples were collected from alpacas, and antibodies against T. gondii and Chlamydia were examined by the modified agglutination test (MAT) and indirect hemagglutination assay (IHA), respectively. Antibodies to N. caninum and BTV were determined by using the commercially available competitive enzyme-linked immunosorbent assay (cELISA) kits, respectively. The overall seroprevalence of T. gondii was 9.16% (95% CI 5.59-12.73) in the three sampled counties, of which, no T. gondii-seropositive samples were detected in alpacas in Fanshi County. Gender differences in the T. gondii seroprevalence were observed. The overall Chlamydia seroprevalence was 13.94% (95% CI: 9.66-18.22), and there was a statistically significant difference in Chlamydia seroprevalence in alpacas between the two counties, Jiexiu and Fanshi. All serum samples tested negative for N. caninum and BTV antibodies, respectively. To our knowledge, this is the first report of T. gondii and Chlamydia seroprevalence in alpacas in China, which provides baseline information for controlling T. gondii and Chlamydia infection in alpacas in China., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Toxoplasma gondii and Chlamydia are common protozoan pathogens, which can pose health risks to people around the world and cause considerable economic losses. Although information on the seroprevalence of T. gondii and Chlamydia in chickens can be found in China, knowledge on the infection of these two diseases in rural chickens, ducks, and geese is limited. Therefore, blood samples from 377 chickens, 268 ducks, and 379 geese were taken from rural areas in seven cities in northeastern China, and their seropositivity was analyzed by the indirect hemagglutination antibody (IHA) test with a cutoff titer of 1:64. The overall seroprevalence of T. gondii and Chlamydia was 10.6% and 21.0%, respectively. Moreover, the free-range poultry (20.75% and 30.55%) have significantly higher seroprevalences than caged poultry (5.47% and 15.66%) ( p  < 0.001). Moreover, the seroprevalence of T. gondii in older and younger poultry was found to be 5.48% and 12.89%, and those in Chlamydia were 23.53% and 15.16%, respectively. There were significant differences between different ages ( p  < 0.05). But regarding the prevalence of both, it is not clear in this way which one is the prevalence for younger and older for each specific pathogen. Logistic regression analysis suggested that geography were considered as a risk factor for T. gondii infection in this study. Our study is the first report on the seroprevalence of T. gondii and Chlamydia in poultry in rural areas of Jilin Province, China. These data reflect that T. gondii and Chlamydia are widespread in poultry in northeastern China, leading to a risk of infection in human health. Therefore, the prevention and control of Toxoplasma and Chlamydia infection in poultry, other animals, and humans should be strengthened.

We studied livestock abortion and various associated risk factors in the Ili region of northwest China. Livestock abortion prevalence was estimated and correlated with infections (Brucellosis, Salmonellosis, Mycoplasma and Chlamydia seropositivity) and management (farming type and contact with other herds/flocks) risk factors. A total of 2996 serum samples (1406 cow, 1590 sheep) were identified by RBPT (Rose Bengal Plate Test) and c-ELISA (competitive-enzyme linked immunosorbent assay), and they showed the overall seroprevalence of brucellosis in the study area was cow 6.76%, sheep 9.50%. The seroprevalence of brucellosis in X county was cow 7.06%, sheep 9.12%; in H county was cow 11.70%, sheep 10.80%; and in Q county was cow 4.22%, sheep 9.11%. The overall seroprevalence of Mycoplasma in the study area was cow 3.20%, sheep 6.42%. The seroprevalence of Mycoplasma in X county was cow 3.39%, sheep 7.98%; in H county was cow 5.26%, sheep 9.97%; and in Q county was cow 2.11%, sheep 4.33%. The Odds ratio of brucellosis for cow and sheep, respectively, were 45.909 [95% CI 26.912-78.317, P<0.001] and 70.507 [95% CI 43.783-113.544, P<0.001] times higher than other abortion-related factors including mixed farming, contact with other flocks and Mycoplasma infection. A total of 54 samples, including aborted cow (22), sheep (30) fetuses and milk samples (2), were identified as Brucella melitensis (B. melitensis) positive. A total of 38 Brucella were isolated from 16 aborted cow, 20 sheep fetuses and 2 milk samples. All of these isolates were identified, and confirmed, as B. melitensis. A phylogenetic tree showed that the Brucella isolates closely matched the B. melitensis biovar 3 isolated in Inner Mongolia, China, and B. melitensis isolated from Norway and India. These results suggest that B. melitensis biovar 3 is the main pathogen responsible for cow and sheep abortion and also pose a human health risk. Additionally, livestock reproduction can also be influenced by Mycoplasma infection and managerial factors (farming type and contact with other herds/flocks), especially in remote areas., Competing Interests: None of the authors of this paper have a financial or personal relationship with other people or organizations that could inappropriately influence or bias the content of the paper.

Background: WHO recommends that men who have sex with men (MSM) receive gonorrhoea and chlamydia testing, but many evidence-based preventive services are unaffordable. The pay-it-forward strategy offers an individual a gift (eg, a test for sexually transmitted diseases) and then asks whether they would like to give a gift (eg, a future test) to another person. This study examined the effectiveness of a pay-it-forward programme to increase gonorrhoea and chlamydia testing among MSM in China., Methods: We did a randomised controlled superiority trial at three HIV testing sites run by MSM community-based organisations in Guangzhou and Beijing, China. We included MSM aged 16 years or older who were seeking HIV testing and met indications for gonorrhoea and chlamydia testing. Restricted randomisation was done using computer-generated permuted blocks. 30 groups were randomised into three arms (1:1:1): a pay-it-forward arm in which men were offered free gonorrhoea and chlamydia testing and then asked whether they would like to donate for testing of prospective participants, a pay-what-you-want arm in which men were offered free testing and given the option to pay any desired amount for the test, and a standard-of-care arm in which testing was offered at ¥150 (US$22). There was no masking to arm assignment. The primary outcome was gonorrhoea and chlamydia test uptake ascertained by administrative records. We used generalised estimating equations to estimate intervention effects with one-sided 95% CIs and a prespecified superiority margin of 20%. The trial is registered with ClinicalTrials.gov, NCT03741725., Findings: Between Dec 8, 2018, and Jan 19, 2019, 301 men were recruited and included in the analysis. 101 were randomly assigned to the pay-it-forward group, 100 to the pay-what-you-want group, and 100 to the standard-of-care group. Test uptake for gonorrhoea and chlamydia was 56% (57 of 101 participants) in the pay-it-forward arm, 46% (46 of 100 participants) in the pay-what-you-want arm, and 18% (18 of 100 participants) in the standard-of-care arm. The estimated difference in test uptake between the pay-it-forward and standard-of-care group was 38·4% (95% CI lower bound 28·4%). Among men in the pay-it-forward arm, 54 of 57 (95%) chose to donate to support testing for others., Interpretation: The pay-it-forward strategy can increase gonorrhoea and chlamydia testing uptake among Chinese MSM and could be a useful tool for scaling up preventive services that carry a mandatory fee., Funding: US National Institute of Health; Special Programme for Research and Training in Tropical Diseases, sponsored by UNICEF, UNDP, World Bank, and WHO; the National Key Research and Development Program of China; Doris Duke Charitable Foundation; and Social Entrepreneurship to Spur Health., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The aims of this study were to investigate the prevalence and proportion of laboratory-confirmed urethral Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections that were asymptomatic among individuals presenting to clinics in Shenzhen and the risk factors related to asymptomatic CT infection. In a cross-sectional study, eligible individuals were invited to participate in the questionnaire, and urine specimens were collected to identify CT and NG infections using a nucleic acid amplification test (NAAT). Considering the differences in the presentation of symptoms between men and women, this study was stratified by gender. Corresponding outcomes were analyzed by Chi-square test and multivariate logistic regression. A total of 2,871 participants were asymptomatic and included in our analyses: 1120 (39.0%) men and 1751 (61.0%) women. The prevalence of asymptomatic NG and CT infections was 0.9% and 6.2% in men, and 0.4% and 7.9% in women, respectively. The proportion of asymptomatic urethral CT among men with urethral CT was 28.3%; for women, it was 34.2%. For asymptomatic men with CT, 3 independent risk factors were identified: (1) men under the age of 30 (aOR, 1.83; 95% CI, 1.11-3.03); (2) being employed in the commercial service work (2.82; 1.36-5.84); and (3) being recruited through the urological department (2.12; 1.19-3.79). For asymptomatic women with urethral CT, age less than 30 years was a risk factor. In conclusion, a substantial prevalence of asymptomatic CT infections was found among men and women presenting to clinics in Shenzhen. The significant correlation between asymptomatic CT infection and these risk factors could help identify high-risk populations and guide screening., Competing Interests: The authors declare that they have no conflict of interest.

Background: Gonorrhea and chlamydia are common among Chinese men who have sex with men (MSM), but testing rates are low. We developed a pay-it-forward program where men receive a free gonorrhea/chlamydia test and can then donate toward future participants' tests. This study aims to investigate drivers of testing uptake and donation using a mixed methods approach., Methods: We used a sequential explanatory design to explore drivers of testing uptake and donation unique to pay-it-forward through a quantitative cross-sectional survey and a qualitative thematic analysis of semistructured interviews. We collected data on sociodemographics and perceived benefits of pay-it-forward among men offered the pay-it-forward interventionand analyzed testing uptake and donations using descriptive statistics and logistic regression. We then conducted 30 semistructured interviews with men and coded interview data to identify themes., Results: Three hundred and one MSM were offered pay-it-forward and 55% (165/301) received gonorrhea/chlamydia testing. Ninety-one percent (150 of 165) donated any amount with a mean of 58.31 ± 53.39 RMB (US $8.61 ± 7.88), or 39% of the standard price of gonorrhea/chlamydia testing. Getting tested was not associated with income, but donations were higher in the highest income bracket (adjusted odds ratio, 7.12; 95% confidence interval, 1.61-31.52). Fifty-eight percent (94 of 162) selected "more MSM can get tested," and 54% (88 of 162) selected "I can help someone else" as benefits of pay-it-forward. Qualitative themes for drivers of testing and donation included flexible pricing, generosity and reciprocity, and MSM community identity., Conclusions: Quantitative and qualitative results suggest that this pay-it-forward program may increase gonorrhea/chlamydia testing by reducing cost barriers, leveraging generosity and reciprocity, and mobilizing community altruism.

Chlamydia trachomatis (CT) infection has been a major public health threat globally. Monitoring and prediction of CT epidemic status and trends are important for programme planning, allocating resources and assessing impact; however, such activities are limited in China. In this study, we aimed to apply a seasonal autoregressive integrated moving average (SARIMA) model to predict the incidence of CT infection in Shenzhen city, China. The monthly incidence of CT between January 2008 and June 2019 in Shenzhen was used to fit and validate the SARIMA model. A seasonal fluctuation and a slightly increasing pattern of a long-term trend were revealed in the time series of CT incidence. The monthly CT incidence ranged from 4.80/100 000 to 21.56/100 000. The mean absolute percentage error value of the optimal model was 8.08%. The SARIMA model could be applied to effectively predict the short-term CT incidence in Shenzhen and provide support for the development of interventions for disease control and prevention.

Objectives: Ureaplasma urealyticum (UU), Chlamydia trachomatis (CT), and Neisseria gonorrhoeae (NG) are highly prevalent worldwide and may lead to some genital diseases. The objective of this large-scale study was to estimate the prevalence characteristics of UU, CT, and NG among women in Taizhou, Zhejiang Province, China., Methods: A total of 13 303 women who visited the gynecologic outpatient service of Taizhou First People's Hospital in Taizhou from 2013 to 2018 were analyzed. The testing of UU, CT, and NG was performed on the collected vaginal swabs using real-time fluorescence quantitative polymerase chain reaction (RT-PCR) method., Results: The overall infection rates of UU, CT, and NG were 62.04%, 10.20%, and 4.09% in the Taizhou-based population, respectively. The age-specific prevalence showed that younger women (age <25 years) were the preferred period for the positive detection of UU or CT, while elder women (age ≥40 years) had the highest prevalence of NG. In addition, the UU-CT co-infection pattern (7.32%) predominated in the study population, and CT was significantly associated with UU and NG., Conclusions: Our novel data demonstrated that UU, CT, and NG infection are prevalent among women in Taizhou, and comprehensive UU, CT, and NG screening guidelines and treatment policies for this population are warranted., (© 2019 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals, Inc.)

Chlamydia , a kind of obligate intracellular Gram-negative bacteria, can infect humans and animals worldwide, including pigs. However, the information on Chlamydia infection is unavailable in pigs in Shandong province, eastern China. To assess the seroprevalence and risk factors of Chlamydia infection in pigs in Shandong province, eastern China, a total of 2108 serum samples of slaughter pigs were collected between January 2017 and December 2018, and specific antibodies against Chlamydia were detected by the indirect hemagglutination assay. The overall Chlamydia seroprevalence was 24.15% (509/2108, 95% confidence interval: 22.32-25.97). Species, sampling regions, and rearing systems of pigs were considered as risk factors for Chlamydia infection through statistical analysis by SAS analysis ( p  < 0.05). These results indicated that Chlamydia is highly prevalent in slaughter pigs in Shandong province, eastern China, and may pose a potential risk for human health. To our knowledge, this is the first investigation of Chlamydia seroprevalence in slaughter pigs in Shandong province, eastern China. Moreover, this is the first report to compare the Chlamydia seroprevalence between domestic pigs and farmed wild boars in a same study, which may provide important data for preventing and controlling Chlamydia infection in pigs in China.

Background: Chlamydia trachomatis (CT) infection is one of the most pervasive sexually transmitted infections and has high prevalence in urogenital and extra-urogenital sites among men who have sex with men (MSM). This study investigated anatomical site-specific prevalence and genotypes of CT among MSM recruited from three geographic areas in China., Methods: We collected urine specimens and anorectal, pharyngeal swab specimens from 379 MSM. CT infection was identified using polymerase chain reaction and CT genotyping was determined by sequences of the ompA gene., Results: The results indicated that the overall prevalence of CT infection was 18.2% (95% confidence intervals [CIs], 13.9-22.5%) and significantly different between the cities (p = 0.048). The infection was most common at the anorectal site (15.6, 95%CIs 11.6-19.5%) followed by urethral (3.2, 95%CIs 1.4-5.0%) and oropharyngeal sites (1.6, 95%CIs 0.3-2.9%). Genotypes D and G were the most common CT strains in this population but genotype D was significantly predominated in Nanjing while genotype G was in Wuhan. No genotype related to lymphogranuloma venereum was found. CT infection was significantly related to the infection of Neisseria gonorrhoeae (adjusted odds ratio [aOR] 14.27, 95%CIs 6.02-33.83, p < 0.001) and age. Men older than 40 years old were less likely to have a CT infection as compared to men under 30 years old (aOR 0.37, 95% CIs 0.15-0.93, p = 0.03)., Conclusion: The high CT infection prevalence, particularly in the anorectal site, among MSM suggests the necessity to development an integrated CT screening and treatment program specifically focusing on this high-risk population. Surveillance of CT infections should be improved by including both infection and genotype based surveys into the current surveillance programs in China.

Background: This study aims to investigate the difference in vaginal microecology, local immunity and HPV infection among childbearing-age women with different degrees of cervical lesions., Methods: A total of 432 patients were included in this study. Among these patients, 136 patients had LSIL, 263 patients had HSIL and 33 patients had CSCC. These patients were assigned as the research groups. In addition, 100 healthy females were enrolled and assigned as the control group., Results: The microbiological indexes of vaginal secretions were evaluated. Furthermore, the concentrations of SIgA, IgG, IL-2 and IL-10 in vaginal lavage fluid, as well as the presence of HPV, mycoplasma and Chlamydia in cervical secretions, were detected. The results is that: (1) Differences in evaluation indexes of vaginal microecology among all research groups and the control group were statistically significant (P < 0.0001). As the degree of cervical lesions increased, the number of Lactobacillus decreased, and there was an increase in prevalence of bacterial imbalance, and the diversity, density and normal proportion of bacteria was reduced. Furthermore, the incidence of HPV, trichomonads, clue cell and Chlamydia infection increased. Moreover, the positive rate of H 2 O 2 decreased, while the positive rates of SNa and GADP increased. (2) Differences in the ratio of IL-2 and IL-10 in the female genital tract among all research groups and the control group were statistically significant (P < 0.0001)., Conclusions: As the degree of cervical lesions increased, IL-2 decreased, IL-10 increased and IL-2/IL-10 decreased, while SIgA and IgG were elevated. The reduction of dominant Lactobacillus in the vagina, impairment of H 2 O 2 function, flora ratio imbalance, pathogen infections, reduction in IL-2/IL-10 ratio, and changes in SIgA and IgG levels could all be potential factors that influenced the pathogenicity of HPV infection and the occurrence and development of cervical lesions.

This study aimed to estimate the prevalence of chlamydial trachomatis (CT) infection and explore its risk factors among patients attending sexual and reproductive health clinics in Shenzhen, China. We collected demographic and clinical information from attendees (aged 18-49). CT and Neisseria gonorrhoeae (NG) infection was determined by nucleic acid amplification test (NAAT) on self-collected urine specimens. Of 1,938 participants recruited, 10.3% (95% confidence interval [CI]: 9.6%-11.0%) tested positive for CT. Prevalence was similar between men (10.6% [85/804]; 95% CI, 9.5%-11.7%) and women (10.1% [115/1134]; 95% CI: 9.2%-11.0%). Being 18-25 years old (adjusted odds ratio [aOR] = 2.52; 95%CI:1.35-4.71), never tested for CT before (aOR = 2.42; 95%CI: 1.05-5.61) and infected with NG(aOR = 3.87; 95%CI: 2.10-7.10) were independently associated with CT infection. We found that CT infection is prevalent among patients attending sexual and reproductive health clinics in Shenzhen, China. A comprehensive program including CT screening, surveillance and treatment is urgently needed., Competing Interests: The authors have declared that no competing interests exist.

Background: Chlamydia trachomatis may coinfect with human papillomavirus (HPV) and complicate the cervical pathogenesis. This study aimed to evaluate the prevalence, risk factors, and clinical outcomes of HPV/C. trachomatis coinfection in women from Inner Mongolia, China., Methods: We performed a polymerase chain reaction (PCR)-based HPV/C. trachomatis screening and cervical samples were analyzed by thinprep cytologic test. Statistical analysis was used to assess the association between demographic factors and coinfection., Results: Among the 2345 women recruited, the prevalences of HPV, C. trachomatis, and HPV/C. trachomatis coinfection were 36.0%, 14.3%, and 4.8%, respectively. The rate of multiple HPV genotypes was higher in coinfected women. HPV66 was the most frequently identified genotype in coinfected participants. The HPV DNA load was significantly higher in HPV monoinfected cases. In contrast, the DNA load of C. trachomatis was significantly higher in the coinfection group. Risk factors, including single women (odds ratio [OR] = 6.0, 95% confidence interval [CI], 4.044-8.782) and women with multiple sex partners (OR = 1.9, 95% CI, 1.324-2.824), were associated with coinfection. Importantly, coinfection was associated with increased risk for high-grade squamous intraepithelial lesions., Conclusions: HPV and C. trachomatis coinfection is an important risk factor for the progression of cervical lesions.

Background: A high rectal and oropharyngeal sexually transmitted infection (STI) burden has been reported among men who have sex with men (MSM) in many regions, but little data exists on rectal and oropharyngeal STIs among MSM in China. The purpose of this study was to determine the prevalence of gonorrhea and chlamydia at different anatomic sites among MSM in Guangzhou, China., Methods: We recruited a cross-sectional sample of MSM in one Chinese city and collected detailed information about socio-demographic characteristics and sexual behaviors. Men had urine, rectal, and pharyngeal swab samples tested for gonorrhea and chlamydia using nucleic acid amplification tests (NAAT). Univariate and multivariate logistic regressions were used to evaluate factors associated with gonorrhea and chlamydia. Among men without any STI symptoms, we also examined the prevalence of gonorrhea and chlamydia by anatomical site., Results: We enrolled 463 men between January 2015 and March 2017. A total of 58/463 (12.5%) of men had gonorrhea and 84/463 (18.1%) had chlamydia. MSM with gonorrhea were more likely to have been recruited from the STI clinic (OR 3.41, 95% CI 1.94-5.99), living with HIV (OR 2.41, 95% CI 1.18-4.92), diagnosed had STI co-infection (OR 2.55, 95% CI 1.39-4.69). MSM with chlamydia were more likely to be students (OR 1.8, 95% CI 0.99-3.39). Most gonorrhea (34/58, 59%) and chlamydia (64/84, 76%) infections were not associated with STI symptoms., Conclusion: Asymptomatic gonorrhea and chlamydia infection were common in this sample of Chinese MSM. Further research is necessary to determine optimal STI screening programs.

Background: A population-based study of Chlamydia trachomatis (CT) infections is essential in designing a specific control program; however, no large investigation of CT infections among the general population in mainland China has been conducted since 2000. We aimed to determine the prevalence, risk factors, and associated medical costs of CT among residents, 18-49 years of age, in Shandong, China., Methods: From May to August 2016, a multistage probability sampling survey involving 8074 individuals was distributed. Data were collected via face-to-face interviews, followed by self-administered questionnaire surveys. First-void urines were collected and tested for CT and Neisseria gonorrhoeae (NG) using nucleic acid amplification., Results: The weighted prevalence of CT infection was 2.3% (95% confidence interval [CI], 1.5-3.2) in females and 2.7% (1.6-3.8) in males. Women, 30-34 years of age, had the highest prevalence of CT infections (3.5%, 2.6-4.4), while the highest prevalence of CT infections in males was in those 18-24 years of age (4.3%, 0.0-8.8). Neisseria gonorrhoeae infection had a prevalence of 0.1% (0.0-0.3) in women and 0.03% (0.0-0.1) in men. Risk factors for CT infections among females included being unmarried, divorced, or widowed (odds ratio [OR], 95% CI 3.57, 1.54-8.24) and having two or more lifetime sex partners (3.72, 1.14-12.16). Among males, first intercourse before 20 years of age (1.83, 1.10-3.02) and having two or more lifetime sex partners (1.85, 1.14-3.02) were associated with CT infections. The estimated lifetime cost of CT infections in patients 18-49 years of age in Shandong was 273 million (range, 172-374 million) China Renminbi in 2016., Conclusions: This study demonstrated a high burden of CT infections among females < 35 years of age and males < 25 years of age in Shandong. Thus, a CT infection control program should focus on this population, as well as others with identified risk factors.

This study was aimed to estimate the prevalences of chlamydia (CT) and gonococcal (NG) infections and explore risk factors associated with the CT infection among women in Shenzhen, China. We collected socio-demographic and clinical data from women (aged 20-60) and determined positivity of CT or NG by nucleic acid amplification test (NAAT) with self-collected urine specimens. We estimated prevalence of CT and NG and determined risk factors associated with CT infection. Among 9,207 participants, 4.12% (95% confidence interval [CI], 3.71%-4.53%) tested positive for CT and 0.17% (95% CIs, 0.09%-0.25%) for NG. Factors significantly associated with CT infection included being an ethnic minority (ethnicity other than Han China) (Adjusted odds ratio [AOR], 1.9; 95% CI, 1.2-3.0), using methods other than condom for contraception (AOR, 1.5; 95% CI, 1.2-1.8), having a history of adverse pregnancy outcomes (AOR, 1.4; 95% CI, 1.1-1.8), and experiencing reproductive tract symptoms in the past three months (AOR, 1.3; 95% CI, 1.0-1.7). we found that CT infection is prevalent among women in Shenzhen, China and associated with both demographic and behavioral factors. A comprehensive CT screening, surveillance and treatment programme targeting this population is warranted.

Aim: This study explored chlamydia trachomatis (CT), ureaplasma urealyticum (UU) and/or neisseria gonorrhoeae (NG) in 5893 women with urinary tract infections (UTIs) in Shanghai., Methods: From January 2009 to December 2014, 5893 women with UTIs in Shanghai were selected to undergo CT, UU and NG detection. Baseline characteristics including age, education level, occupation, reproductive history, sexual behavior and contraceptive method were obtained for epidemiological analysis., Results: The total CT, UU and/or NG infection rate in the urine samples of 5893 patients was 50.69% (2987/5893), while the infection rate in vaginal secretion samples was 56.22% (3313/5893). The two detection methods were consistent. Patients aged 21-30, service personnel and unemployed persons had the highest rates of CT, UU and/or NG infection, while patients with higher education levels exhibited lower rates. As the number of previous pregnancies, natural births, abortions, sexual partners and the frequency of sexual intercourse increased, the rates of CT, UU and/or NG infection were elevated. Sexual intercourse during the menstruation period, a lack of cleaning before sexual intercourse and the use of intrauterine devices could all lead to an increased rate of CT, UU and/or NG infection., Conclusions: These data revealed that the rate of CT, UU and/or NG infection may be associated with age, education level, occupation, reproductive history, sexual behavior and type of contraceptive method in female patients with UTI in Shanghai., (© 2017 Japan Society of Obstetrics and Gynecology.)

Though vaginal douching is a common practice among female sex workers that could increase the risk of HIV and adverse reproductive health outcomes, it has drawn limited attention. From November 2010 to January 2011, a convenience sample of female sex workers was recruited in three cities in China. Face-to-face interviews were conducted to gather socio-demographic and behavioural information. Blood samples were collected for syphilis serological tests. Endo-cervical swabs were collected and tested for Neisseria gonorrhoeae and Chlamydia trachomatis by polymerase chain reaction. A logistic regression model was used to determine factors associated with vaginal douching and the association between vaginal douching and sexually transmitted infection. A total of 1032 eligible female sex workers were enrolled. The overall prevalence of any sexually transmitted infection (syphilis, Chlamydia trachomatis or Neisseria gonorrhoeae) and vaginal douching with disinfectant were 23.4% and 23.1%, respectively. Factors independently associated with douching practice included study sites, venue types, ethnicity, having regular partner and sexually transmitted infection history. No significant association was found between vaginal douching and current sexually transmitted infection. Vaginal douching with disinfectant after sex with clients seemed to be a prevalent practice among female sex workers in China. Prevention programmes targeting female sex workers should incorporate components about the adverse health outcomes associated with vaginal douching., (© The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Background: In China, the HIV/AIDS epidemic is expanding among men who have sex with men (MSM). As independent risk factors of HIV infection, the epidemics of Chlamydia (CT) and Gonorrhea (NG) in MSM were not well studied, particular for the risk factors of these infectious. The objectives of current reported study were to understand the dynamics of HIV and other sexual transmitted infections (STIs) among MSM in Jiangsu, China, and to measure factors that correlated with STIs., Methods: In order to gain more participants, a multisite cross-sectional study design was used in our study, by using convenience-sampling to recruit MSM in two Changzhou and Yangzhou, Jiangsu, China, between the July and October of 2009., Results: In this comprehensive survey involving MSM in two cities of Jiangsu province of China, the prevalence of STIs of CT (6.54%), NG (3.63%), syphilis (20.34%) and HIV (11.62%) were measured. Overall, the STIs prevalence (CT, NG or syphilis) for the participants in our study was 26.39%, meanwhile, 3.4% (14 out of the 413) participants had at least two kinds of STIs. Meeting casual partners at parks, public restrooms or other public areas, having had anal sex with men in the past six months, having had STI symptoms in the past year were positively correlated with STIs positive, with adjusted ORs of 4.61(95%CI 1.03-20.75), 1.91(95%CI 1.14-3.21) and 2.36(95%CI 1.07,5.24)., Conclusion: Our study findings reiterate the fact that Chinese MSM are highly susceptible to acquiring syphilis, CT, NG and HIV, and there is an urgent need for intervention targeted towards this population. Behavioral measures should constitute an important part of the targeted intervention. Furthermore, the already implemented preventive and diagnostic services for HIV should be expanded to include syphilis CT and NG, too.

Objectives: To estimate the prevalence of sexually transmitted infections (STIs) among female sex workers (FSWs) in the Jiangsu Province, China and measure the association of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections with their potential correlates., Design: A cross-sectional study on a representative sample of FSWs in Yangzhou and Changzhou cities of Jiangsu was conducted., Methods: 185 sex-work venues in Yangzhou and 174 in Changzhou were selected by stratified random sampling. 2972 FSWs (1108 in Yangzhou and 1864 in Changzhou), aged 15 years or more, who agreed to participate and provided blood sample for HIV and syphilis testing were interviewed in these venues. Cervical specimens from 849 randomly chosen participants were then tested for CT and NG., Results: Proportions of young, school-educated, currently married FSWs who were living alone, migrated from other provinces and engaged in unprotected vaginal intercourse in past 3 months (UVI) were relatively high. Prevalence of HIV, syphilis, CT and NG were 0.20%, 4.88%, 14.61% and 5.42% respectively. Younger age, living alone or with persons other than partners/family members, engaging in UVI and having other STIs seemed to be associated with higher risk of CT or NG infection. Being divorced/widowed and working in middle/low-level venues were identified as additional risk factors for NG., Conclusions: Based on a representative sample, this initial effort to identify the correlates of CT/NG infections among FSWs of Jiangsu revealed that focused interventions targeting high-risk FSWs are urgently required for controlling STI epidemics in Yangzhou and Changzhou where substantial number of STI cases were identified.

Chlamydia abortus, an important pathogen in a variety of animals, is associated with abortion in sheep. In the present study, 1732 blood samples, collected from Tibetan sheep between June 2013 and April 2014, were examined by the indirect hemagglutination (IHA) test, aiming to evaluate the seroprevalence and risk factors of C. abortus infection in Tibetan sheep. 323 of 1732 (18.65%) samples were seropositive for C. abortus antibodies at the cut-off of 1:16. A multivariate logistic regression analysis was used to evaluate the risk factors associated with seroprevalence, which could provide foundation to prevent and control C. abortus infection in Tibetan sheep. Gender of Tibetan sheep was left out of the final model because it is not significant in the logistic regression analysis (P > 0.05). Region, season, and age were considered as major risk factors associated with C. abortus infection in Tibetan sheep. Our study revealed a widespread and high prevalence of C. abortus infection in Tibetan sheep in Gansu province, northwest China, with higher exposure risk in different seasons and ages and distinct geographical distribution.

The occurrence and impact of chlamydial infections in Western livestock is well documented in the international literature, but less is known aboutthese infections in livestock in the People's Republic of China. China's livestock production and its share in the global market have increased significantly in recent decades. In this review, the relevant English and Chinese literature on the epidemiology of chlamydial infections in Chinese livestock is considered, and biosecurity measures, prophylaxis and treatment of these infections in China's livestock are compared with Western practices. Chlamydial infections are highly prevalent in Chinese livestock and cause important economic losses, as they do in the rest of the world. Surveillance data and diagnostic results of abortion outbreaks in cattle, sheep and goats highlight the importance of virulent chlamydial infections in China's major ruminant species in many of China's provinces, autonomous regions and municipalities. Data from many of China's provincial divisions also indicate the widespread presence of chlamydial infections in industrially reared swine across the country. Less is known about chlamydial infections in yak, buffalo and horses, but available reports indicate a high prevalence in China's populations. In these reports, chlamydiosis was related to abortions in yak and pneumonia in horses. In Western countries, chlamydial infections are principally treated with antibiotics. In China, however, traditional medicine is often used in conjunction with antibiotics or used as an alternative treatment.

Chlamydia are Gram-negative obligate bacteria that cause a wide range of diseases in humans and animals. To assess the risk of zoonosis posed by pigs, a total of 920 serum samples were collected from pigs in 11 administrative cities in Jiangxi province, south-eastern China, and the seroprevalence of Chlamydia antibodies was investigated by an indirect haemagglutination assay. The pathogen-specific antibodies were detected in 539 (58.59 %) pigs with seroprevalence ranging from 33.33 % (Jingdezhen) to 90.91 % (Pingxiang) among different cities (P<0.05). The highest prevalence was found in pregnant sows (80.89 %, 127/157), followed by breeding boars (79.37 %, 50/63), suckling sows (77.01 %, 67/87), fattening pigs (69.32 %, 61/88) and non-pregnant sows (62.5 %, 180/288). Piglets had the lowest prevalence of 22.78 % (54/237). The seroprevalence of Chlamydia infection among different categories of pigs was also significantly different (P<0.05). These results indicate that Chlamydia is highly prevalent in pigs in Jiangxi province and our results indicate that the presence of Chlamydia exposure in pigs may pose a potential threat to human health.

We investigated Chlamydia trachomatis strains from Nanjing, China, and whether these strains differed from Amsterdam, the Netherlands. C. trachomatis type was determined with multilocus sequence typing. Most strains were specific to Nanjing, but some clustered with strains from Amsterdam. This demonstrates a geographical variation in C. trachomatis previously left undetected.

Background: Chlamydiaceae is a family of obligate intracellular pathogens with a worldwide distribution in many animal species, including humans. No information exists on the prevalence of Chlamydia felis infections in cats and dogs in Lanzhou, the geographical center of China. The aim of this study was to carry out a census of cats and dogs in Lanzhou and document the seroprevalence of C. felis exposure in these companion animals., Results: In this study, blood samples were collected from 485 animals (221 cats and 264 pet dogs) in Lanzhou between November 2010 and July 2011 to identify antibodies against C. felis. Thirteen of 221 (5.9%) cats and 32 of 264 (12.1%) pet dogs were positive for C. felis infection using indirect hemagglutination at a cutoff of 1:16. The seroprevalence in household and stray cats was 3.9% and 14.3%, respectively, and the difference was statistically significant (P < 0.05). Among different age groups, the seroprevalence in cats varied from 1.9 to 7.9%, and that in dogs ranged from 9.6 to 20.4%; however, the differences were not statistically significant (P > 0.05)., Conclusions: This is the first report of the seroprevalence of C. felis exposure in cats and dogs in Lanzhou, northwestern China. Our results indicate that the presence of C. felis exposure in cats and dogs may pose a potential threat to human health.