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Little is known about the frequency of Zika virus (ZIKV) infections in Sudan. The aim of this study was to obtain data on the prevalence of ZIKV infections and the immunity of the population in the country. To this end, 198 sera obtained between December 2012 and January 2013 in different regions in Sudan were examined for neutralizing antibodies against ZIKV, dengue virus (DENV), and yellow fever virus (YFV). The sera were non-randomly selected. The neutralization titers were compared with each other and with the WHO 1st International Standard for anti-Asian lineage Zika virus antibody. Twenty-six sera neutralized ZIKV. One-third of these sera had higher neutralization titers against ZIKV than against DENV-2 and -3. Two sera showed higher neutralization titers than the WHO standard for ZIKV antibodies. These data suggest occasional ZIKV infections in Sudan. The low percentage of sera in this cohort that neutralized ZIKV indicates that, in the study period, the population was susceptible to ZIKV infection.

This is a SARS-CoV-2 seroepidemiological study in a pediatric population (0–16 years) during the BA.5 Omicron predominance period in the Athens metropolitan area. Serum samples were tested for SARS-CoV-2 nucleocapsid antibodies (Abs-N), representing natural infection during three periods of BA.5 predominance: 1 May 2022–31 August 2022 (period A), 1 September 2022–31 December 2022 (period B), and July 2023 (period C). Εpidemiological data were also collected. Additionally, in period C, Abs-N-seronegative samples were tested for SARS-CoV-2 spike antibodies (Abs-S). A total of 878 children were tested (males: 52.6%), with a median age (IQR) of 96 (36–156) months; the number of cases of seropositivity during the three periods were as follows: A: 292/417 (70%), B: 288/356 (80.9%), and C: 89/105 (84.8%), with p < 0.001. SARS-CoV-2 seropositivity increased from period A to C for children 0–1 year (p = 0.044), >1–4 years (p = 0.028), and >6–12 years (p = 0.003). Children > 6–12 years had the highest seropositivity rates in all periods (A: 77.3%, B: 91.4%, and C: 95.8%). A significant correlation of monthly median Abs-N titers with monthly seropositivity rates was detected (rs: 0.812, p = 0.008). During period C, 12/105 (11.4%) Abs-S-seropositive and Abs-N-seronegative samples were detected and total seropositivity was estimated at 96.2% (101/105). The findings of this study indicate a high SARS-CoV-2 exposure rate of children during the BA.5 predominance period and suggest that in future seroepidemiological studies, both antibodies should be tested in Abs-N-seronegative populations.

A seroepidemiological study was conducted in 2018 to assess diphtheria and tetanus antibodies in Guangzhou, China. Diphtheria and tetanus antibody concentrations were measured with an enzyme-linked immunosorbent assay. A total of 715 subjects were enrolled in the study. The overall diphtheria and tetanus toxoid IgG-specific antibody levels were 0.126 IU/mL (95% CI: 0.115, 0.137) and 0.210 IU/mL (95% CI: 0.185, 0.240), respectively; the overall positivity rate was 61.82% (95% CI: 58.14, 65.39) and 71.61% (95% CI: 68.3, 74.92), respectively. The diphtheria and tetanus antibody concentration was decreased by age and increased by doses. The geometric mean concentrations and positivity rate of diphtheria and tetanus antibodies were lowest and below the essential protection level in people over 14 years of age. Compared to children and adolescents, middle-aged people and the aged are at much higher risk of infection with Corynebacterium diphtheriae and Clostridium tetani. The current diphtheria and tetanus immunization schedule does not provide persistent protection after childhood. There is an urgent need to adjust the current immunization schedule.

Objectives: To assess antibody responses to an inactivated SARS-CoV-2 vaccine in individuals aged 50 and older. Methods: We conducted a post-market cross-sectional seroepidemiology study. We recruited 4,632 vaccinated individuals aged 50 and older, measured their total serum SARS-CoV-2-specific antibody (TA), and collected correlates. The primary outcome was the geometric mean titer (GMT) of TA, and the secondary outcome was the decline of TAwith age. Univariate, bivariate, andmultivariate analyseswere used to examine the associations of the TA GMT with age, and trend analyses were used to test whether their associations were significant. Results: All participants had a detectable TA, which was generally at a low level across all age groups. The TA GMT (95% CI) in AU/mL was 3.05 (2.93, 3.18); the corresponding arithmetic mean (95% CI) was 17.77 (16.13, 19.42) in all participants and 4.33 (3.88, 4.84), 3.86 (3.49, 4.28), 3.24 (2.92, 3.59), 2.77 (2.60, 2.96), and 2.65 (2.48, 2.83) in the age groups of 50-54, 55-59, 60-64, 65-74, and 75 years or older, respectively. The TA GMT decreased with age with a Ptrend < 0.001. The TA GMT was significantly lower in those with hypertension or diabetes compared to those with neither. Conclusion: The inactivated SARS-CoV-2 vaccine is effective in individuals aged 50 and older. This is the first study that has found an inverse dose-response relationship between ages and the low-level TAs. Older people, especially those with chronic diseases, should get the SARS-CoV-2 vaccine, and their vaccination frequency, dose, and method may need to be different from those of younger people. [ABSTRACT FROM AUTHOR]

This study aimed to assess the seroprevalence of SARS-CoV-2 and disease symptoms in Malakand, Pakistan. 623 samples with suspected SARS-CoV-2 were collected from different regions of Malakand and analyzed to detect SARS-CoV-2 IgG antibodies using ELISA. 306 (49.1%) 0 f 623 patients were anti-SARS-CoV-2 IgG reactive, with a higher prevalence in males (75%) than females (25%). In this study, we enrolled two groups, subjects working in a non-medical setting and subjects working in a medical setting. Clinical symptoms were statistically linked with SARS-CoV-2. Four weeks of follow-up analysis of IgG titers in health care workers showed an increase in IgG antibodies titer. This study gives insights into the community-based spread of SARS-CoV-2 infection, associated immunity, and herd immunity in the studied population. This study can provide insights to the government about early vaccination of this population as most of the population is not yet vaccinated. [ABSTRACT FROM AUTHOR]

Leptospirosis is a significant worldwide zoonotic infectious disease that infects a wide range of animals and humans. Leptospira will colonize the animal's urinary and reproductive systems and be excreted with urine, potentially causing a wide range of infections. Dogs are an essential host for Leptospira, and epidemiological investigation studies of leptospirosis must be conducted to clarify the prevalence of leptospirosis and to reduce the risk of transmission to humans. This study aimed to investigate the seroepidemiology of leptospiral infection in dogs from Changchun, China, using Microscopic Agglutination Test (MAT). A total of 1053 canine blood samples were collected and tested by MAT. The positive rate of MAT was approximately 19.1%. The main prevalent Leptospira serogroups were L. Icterohaemorrhagiae (8.1%), L. Canicola (7.6%), L. Australis (5.3%), L. Ballum (4.7%) and L. Pyrogenes (4.2%). No statistically significant difference among different varieties, sexes and sampling seasons (p > 0.05), except the age (p < 0.05). The seropositive rate was much higher in adult and aged dogs than in juvenile dogs. Our results showed the seroprevalence and the prevalent serogroup of Canine leptospirosis in Changchun, China. [ABSTRACT FROM AUTHOR]

Porcine epidemic diarrhea (PED) is an intestinal disease caused by the porcine epidemic diarrhea virus (PEDV) and affects Mexico's swine industry. Despite the disease initially being described in Mexico in 2013, there has been no research into the virus's seroepidemiology carried out in Mexico. Thus, the goal of this study was to develop an indirect ELISA (iELISA) based on a recombinant N-terminal domain truncated spike (S) protein (rNTD-S) of PEDV to evaluate serum obtained from different pig-producing states in Mexico. A total of 1054 sera were collected from pig farms, slaughterhouses, and backyard production in the states of Aguascalientes, Guanajuato, Hidalgo, Jalisco, Morelos, Queretaro, Sinaloa, and Veracruz between 2019 and 2021. The rNTD-S protein was expressed in E. coli BL21 (DE3) cells. Negative and positive serum samples used in the iELISA were previously tested by Western blot. According to our findings, 61.66% of the serum samples (650/1054) were positive, with Jalisco having the highest percentage of positive samples, at a rate of 21.44% (226/1054). This is the first seroepidemiology study of PEDV carried out in Mexico, revealing that the virus is still circulating since the initial outbreak; furthermore, it provides an overview of PEDV's spread and high level of persistence across the country's key swine-producing states. [ABSTRACT FROM AUTHOR]

Lassa fever virus (LASV) is the causative agent of Lassa fever, a disease endemic in West Africa. Exploring the relationships between environmental factors and LASV transmission across ecologically diverse regions can provide crucial information for the design of appropriate interventions and disease monitoring. We investigated LASV exposure in 2 ecologically diverse regions of Guinea. Our results showed that exposure to LASV was heterogenous between and within sites. LASV IgG seropositivity was 11.9% (95% CI 9.7%–14.5%) in a coastal study site in Basse-Guinée, but it was 59.6% (95% CI 55.5%–63.5%) in a forested study site located in Guinée Forestière. Seropositivity increased with age in the coastal site. We also found significant associations between exposure risk for LASV and landscape fragmentation in coastal and forested regions. Our study highlights the potential link between environmental change and LASV emergence and the urgent need for research on land management practices that reduce disease risks.

In 2019, a community-based, cross-sectional carriage survey and a seroprevalence survey of 1,216 persons 1–55 years of age were conducted in rural Vietnam to investigate the mechanism of diphtheria outbreaks. Seroprevalence was further compared with that of an urban area that had no cases reported for the past decade. Carriage prevalence was 1.4%. The highest prevalence, 4.5%, was observed for children 1–5 years of age. Twenty-seven asymptomatic Coerynebacterium diphtheriae carriers were identified; 9 carriers had tox gene–bearing strains, and 3 had nontoxigenic tox gene–bearing strains. Child malnutrition was associated with low levels of diphtheria toxoid IgG, which might have subsequently increased child carriage prevalence. Different immunity patterns in the 2 populations suggested that the low immunity among children caused by low vaccination coverage increased transmission, resulting in symptomatic infections at school-going age, when vaccine-induced immunity waned most. A school-entry booster dose and improved infant vaccination coverage are recommended to control transmissions.

Background and aims: According to evidence, a hydatid cyst is one of the most important health issues in most parts of the world. This study aimed to investigate the frequency of human hydatidosis in patients referred to health service centers in Hamadan province in 2019 using the enzyme-linked immunosorbent assay (ELISA) method. Methods: In this cross-sectional study, blood samples were collected from 300 patients referred to medical diagnostic laboratories in Hamadan and evaluated for the presence of immunoglobulin G antibodies against hydatid cysts by ELISA. The data were analyzed using SPSS software. Results: Out of 300 samples, 16 (5.3%) cases were positive, including 10 (5.6%) cases of the residents of urban areas and 6 (4.9 %) cases from those residing in rural areas. Moreover, of all the positive cases, 8 (50%) cases were males and 8 (50%) cases were females. The highest percentage of infection (45.5%) was observed in the age group 20-30 years. Conclusion: The findings indicated that human hydatidosis is a public health problem in this province. The implementation of control and prevention programs, as well as increasing the knowledge of people, can help in controlling and reducing infection in humans and livestock.

Domestic and wild dogs of all ages and breeds are susceptible to Canine Coronavirus (CCoV) infections and be seen in Türkiye and amongst world. CCoV has recently been declared a zoonotic disease agent and the eighth pathogenic human coronavirus. This study was conducted on 143 naturally infected dogs with gastroenteritis which were not vaccinated against CCoV in Türkiye in 2015-2020. The data of dogs were analyzed seroepidemiologically, clinicopathologically and statistically. CCOV antibodies in serum and CCOV antigens in stool were detected by ELISA and lateral immunochromatography. The rising CCoV IgG antibody titers were detected at all dogs and were as follows; 64 ng/L in 81 (81%) dogs. CCOV and Canine Parvovirus (CPV) antigen were detected together in the stool of the 41 (28.7%) dogs. As a result, it was concluded that the CCOV agent is in circulation among dogs living in Türkiye. CCOV and CPV can cause co-infections and increased mortality. Although infection can be seen in dogs of all ages, it can be seen more frequently in dogs younger than 1 year of age, and especially in dogs younger than 6 months, and can cause enteritis, low hemoglobin, erythropenia, lymphopenia, leukopenia, thrombocytopenia, and hypoproteinemia.

We aimed to measure the seroprevalences and levels of anti-SARS-CoV-2 IgG in children, unvaccinated and vaccinated adults in five districts of Bangladesh and thus, investigate the association of seroprevalence and anti-SARS-CoV-2 IgG level with respect to different attributes of study participants. In the present study, the seroprevalences and levels of plasma anti-SARS-CoV-2 IgG were measured in children (n = 202), unvaccinated adults (n = 112), and vaccinated adults (n = 439) using quantitative ELISA. The overall seroprevalence in the three groups of the study participants were 58.3% (90%CrI: 52.3–64.2%), 62.2% (90%CrI: 54.4–70.0%) and 90.7% (90%CrI: 88.3–92.9%), respectively. Multivariate logistic and linear regression revealed no significant association of seropositivity and levels of anti-SARS-CoV-2 IgG with the baseline characteristics of the children. AB blood group (vs A; aOR=0.21, 95% CI: 0.04–0.92, p = 0.04), O blood group (vs A; aOR=0.09, 95% CI: 0.02–0.32, p = 0.0004), BMI (aOR=1.61, 95% CI: 1.14-2.37, p = 0.01) and overweight obesity status (vs normal, aOR=0.12, 95% CI: 0.02-0.76, p = 0.03) were significantly associated with seropositivity in unvaccinated adults after adjusting for confounders. Age (p = 0.002) was significantly associated with anti-SARS-CoV-2 level in vaccinated adults after adjusting for confounders. Most of the children and unvaccinated adults belonged to the lower antibody response class which implicates the necessity of vaccination. This study portrays a better way of evaluating transmission of virus and gain a better understanding of the true extent of infection as illustrated by the high rates of seroprevalences in children and unvaccinated adults. The findings of this study depicted from the antibody response also suggest the importance of vaccination. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The epidemiology of hepatitis A virus (HAV) infection is influenced by variables such as age, sex, environmental conditions, and vaccination status. This study aimed to evaluate HAV seropositivity after the inclusion of hepatitis A vaccination in the national childhood immunization program and identify demographic risk factors of the susceptible population before routine vaccination. PATIENTS AND METHODS: This cross-sectional epidemiological study was conducted by retrospectively examining the laboratory records of patients who underwent HAV serology testing in a tertiary care center in eastern Turkey between 2008 and 2019. RESULTS: Overall immunity to HAV was 81.6%. According to birthplace and year, the rate of anti-HAV positivity was higher among people born before 2006 in the Southeast and Eastern Anatolia regions. For those born in 2012 or later, the lowest seropositivity was among those born in the Southeast region, while it was over 60% in the other regions. When analyzed by year of birth, the lowest seropositivity was in those born between 1994 and 2011, and the frequency of seropositivity increased with age. Of those born between 1982 and 1999, the seropositivity rate was higher among men than women. Rural dwellers born before 2012 had higher seropositivity than urban dwellers. Among those born before the introduction of routine childhood HAV vaccination, female sex, urban dwelling, and each additional year of age were identified as independent demographic risk factors for HAV susceptibility. CONCLUSIONS: Socioeconomic development and immunization programs have altered HAV seroprevalence patterns. Planning catchup vaccinations, especially in adolescents and young adults (born in 1994-2011) with low seropositivity and ensuring the continuity of hygiene and sanitation practices are important to protect the susceptible population. [ABSTRACT FROM AUTHOR]

Hepatitis E virus (HEV) is an increasingly recognized etiological agent of acute, chronic and extrahepatic human infections with primarily zoonotic origin in Europe. Limited numbers of comprehensive population-based studies are available related to HEV seroepidemiology, especially from Central Europe. The aim of this study was to investigate the seroprevalence and trends of total and IgM antibodies against HEV in different age groups in the population of South Transdanubia, Hungary, within a thirteen years long period between the years 2010 and 2022. We retrospectively analysed the serological test results of HEV total and HEV IgM antibodies carried out by ELISA technique using Dia.Pro (Diagnostic Bioprobes, Italy) kit from serum samples collected from patients with or without hepatitis between January 1, 2010 and December 31, 2022. The number of tested samples (∑6,996 for total antibody and ∑6,582 for IgM) increased during the study period. The average HEV total and the IgM antibody seropositivities were 33% (2,307/6,996 samples) and 9.6% (642/6,582 samples), respectively, in the study population. The HEV total antibody seropositivity varied in different age groups between 3.9% (age group 1–5 years) and 58.6% (86–90 years) and showed an increasing positivity by age. At the age groups >50 years, nearly half (43%) of the population had antibodies against HEV. The HEV IgM positivity had an increasing trend of up to 13.9% in the age group 81–85 years. High HEV total and IgM antibody seroprevalence were detected in South Transdanubia, Hungary, confirming that this region is highly endemic for HEV infections in Europe. [ABSTRACT FROM AUTHOR]

Background and Objectives Typhoid is a contagious disease transmitted through food and water and is a public health problem worldwide, especially in developing countries. The present study aimed to evaluate the seroprevalence of typhoid fever in suspected patients referred to the Laboratory of Jahad Daneshgahi, Ahvaz, Iran. Subjects and Methods This retrospective study was conducted on all patients suspected of typhoid fever who were referred to the Laboratory of Jahad Daneshgahi in Ahvaz, Iran, in a 10-year period from 2011-2020. The Widal serological test was considered positive 1.160 and above. Data were analyzed using SPSS software (version 22) and Chi-square test. Results Out of 8,642 patients, 88 (1.02%) cases were seropositive. Despite the trend of changes in positive cases from 0.4% in 2011 to 1.4% in 2015 and its zigzag diagram in different years, no statistically significant difference was observed between the positive cases by year (P=0.08). The lowest and highest seropositive frequencies were in summer and winter seasons (0.8% ver.1.2%); and in October and February months (0.4 ver.1.6%), respectively (P=0.43). Although the frequency of seropositive cases of typhoid fever was higher in women (1.07%) than in men (0.97%), this difference was not statistically significant (P=0.37). The highest frequency of seropositive cases was observed in the age group under 15 years (1.3%) and the lowest in the age group over 65 years [0.6%; P=0.56]. Conclusion The obtained results showed that the changes in typhoid fever in this period of time were zigzag and had no constant trend. Moreover, no statistically significant difference was observed between males and females at different ages. The findings of this study could be helpful for healthcare policymakers in understanding the epidemiology of typhoid fever in this region. [ABSTRACT FROM AUTHOR]

To investigate the antigenic changes in parechovirus 1 (PeVA1), seroepidemiological analyses were performed against the Harris strain (Harris), isolated in 1956, and PeVA1/Yamagata.JPN/2021‐4785, isolated in 2021, using immune sera and 207 and 237 human serum specimens collected in 2021 and 1976, respectively. Although rabbit immune sera showed the highest neutralization antibody (NT‐Ab) titers against the immunized viruses at 1:12 800–1:102 400, they were cross‐reactive at 1:400–1:800. All 62 Yamagata isolates obtained between 2001 and 2021 (Yamagata strains), belonging to phylogenetic lineage 1B, reacted more strongly (mostly 4–64 times) to antiserum against PeVA1/Yamagata.JPN/2021‐4785 than to antiserum against Harris, belonging to phylogenetic lineage 1 A. Human serum specimens obtained in 2021 showed higher NT‐Ab titers against PeVA1/Yamagata.JPN/2021‐4785, whereas those obtained in 1976 had similar NT‐Ab titers against both strains. These findings suggested that Yamagata strains and Harris were antigenically cross‐reactive, although there were differences. There are still high NT‐Abs titers present against Harris in 2021 in particular, indicating that PeVA1 has been in circulation with high immunity in the population. In conclusion, this study suggested that PeVA1 has been endemically perpetuated with only minor antigenic changes as well as with high immunity over several decades in the community. [ABSTRACT FROM AUTHOR]

IntroductionIn Brazil, an estimated 1.1 million people are infected with Trypanosoma cruzi, the causative agent of Chagas disease (CD). Despite the high number of cases, the estimated prevalence of infection per 100 inhabitants is low (0.03). However, the actual number of chronically infected individuals is still unknown. Therefore, we sought to determine the prevalence of chronic CD in at-risk individuals in Caraíbas (Bahia, Brazil) through active case finding.MethodsA total of 572 individuals living in rural or urban areas of Caraíbas were eligible for the study. A serum sample was collected from 226 individuals, and the diagnosis performed according to international guidelines.ResultsThe overall prevalence of anti-T. cruzi IgG was 4.42%. The median age of anti-T. cruzi IgG-positive individuals was 54.5 years, and the female-to-male ratio was 1.5:1. The prevalence of anti-T. cruzi IgG was similar in rural (4.29%) and urban areas (4.65%).DiscussionCompared with national estimates, we concluded that Caraíbas had a high prevalence for chronic CD and a high risk for persistent transmission. Through our study, it was possible to monitor individuals who were unaware of their clinical condition, thus improving their quality of life.

Objective: To evaluate the socioeconomic patterns of SARS-CoV-2 antigen contacts through infection, vaccination or both (“hybrid immunity”) after 1 year of vaccination campaign.Methods: Data were derived from the German seroepidemiological Corona Monitoring Nationwide study (RKI-SOEP-2; n = 10,448; November 2021–February 2022). Combining serological and self-report data, we estimated adjusted prevalence ratios (PR) of SARS-CoV-2 infection, COVID-19 vaccination, basic immunization (at least two SARS-CoV-2 antigen contacts through vaccination and/or infection), and three antigen contacts by education and income.Results: Low-education groups had 1.35-times (95% CI 1.01–1.82) the risk of SARS-CoV-2 infection compared to high-education groups. COVID-19 vaccination (at least one dose) and basic immunization decreased with lower education and income. Low-education and low-income groups were less likely to have had at least three antigen contacts (PR low vs. high education: 0.74, 95% CI 0.65–0.84; PR low vs. high income: 0.66, 95% CI 0.57–0.77).Conclusion: The results suggest a lower level of protection against severe COVID-19 for individuals from low and medium socioeconomic groups. Pandemic response and vaccination campaigns should address the specific needs and barriers of these groups.

Background & Aims: Rat hepatitis E virus (Rocahepevirus ratti; HEV-C1) is an emerging cause of hepatitis E that is divergent from conventional human-infecting HEV variants (Paslahepevirus balayani; HEV-A). Validated serological assays for HEV-C1 are lacking. We aimed to develop a parallel enzymatic immunoassay (EIA) system that identifies individuals with HEV-C1 exposure. We also aimed to conduct the first HEV-C1 seroprevalence study in humans using this validated EIA system. Methods: Expressed HEV-A (HEV-A4 p239) and HEV-C1 (HEV-C1 p241) peptides were characterised. Blood samples were simultaneously tested in HEV-A4 p239 and HEV-C1 p241 IgG EIAs. An optical density (OD) cut-off-based interpretation algorithm for identifying samples seropositive for HEV-A or HEV-C1 was validated using RT-PCR-positive infection sera. This algorithm was used to measure HEV-C1 seroprevalence in 599 solid organ transplant recipients and 599 age-matched immunocompetent individuals. Results: Both peptides formed virus-like particles. When run in HEV-A4 p239 and HEV-C1 p241 EIAs, HEV-A and HEV-C1 RT-PCR-positive samples formed distinct clusters with minimal overlap in a two-dimensional plot of optical density values. The final EIA interpretation algorithm showed high agreement with RT-PCR results (Cohen’s κ = 0.959) and was able to differentiate HEV-A and HEV-C1 infection sera with an accuracy of 94.2% (95% CI: 85.8–98.4%). HEV-C1 IgG seroprevalence was 7/599 (1.2%) among solid organ transplant recipients and 4/599 (0.7%) among immunocompetent individuals. Five of 11 (45.5%) of these patients had history of transient hepatitis of unknown cause. Conclusions: HEV-C1 exposure was identified in 11/1198 (0.92%) individuals in Hong Kong indicating endemic exposure. This is the first estimate of HEV-C1 seroprevalence in humans. The parallel IgG EIA algorithm is a valuable tool for investigating epidemiology and risk factors for HEV-C1 infection. Impact and Implications: Rat hepatitis E virus has recently been discovered to infect humans, but antibody tests for this infection are lacking, making it difficult to gauge how common this infection is. We developed an antibody test algorithm that can identify individuals with past rat hepatitis E virus exposure. We used this algorithm to estimate rat hepatitis E exposure rates in humans in Hong Kong and found that approximately 1% of all tested people had been exposed to this virus previously.

The underestimation of the pertussis burden prompted our study to investigate the prevalence of recent pertussis infection, its associated factors, and antibody titer changes in the same individuals in Vietnam. Two cross-sectional surveys were conducted in Nha Trang in 2017 and Quang Ngai in 2019, representing high- and low-vaccine-coverage areas, respectively. Serum anti-pertussis toxin immunoglobulin-G (anti-PT IgG) ≥ 62.5 IU/mL by ELISA indicated infection in the previous 12 months. In Nha Trang, the participants of the 2017 survey were followed up in 2019. Logistic regression was used to determine the odds ratios for the characteristics associated with anti-PT IgG ≥ 62.5. The age-stratified prevalence in patients aged >2 years ranged from 2.1% (age 26–35) to 9.6% (3–5) in Nha Trang (2017) and from 7.2% (age 26–35) to 11.4% (6–15) in Quang Ngai. The prevalence tended to be higher in Quang Ngai across all age groups. Cough, recent antibiotic use, and smoking in Nha Trang were positively associated with an anti-PT IgG of ≥62.5, and having been diagnosed with pertussis and persistent cough with paroxysms/whoop in Quang Ngai were positively associated with an anti-PT IgG of ≥62.5. No nasopharyngeal swabs were positive for Bordetella pertussis using real-time PCR. The geometric mean of the IgG titer ratio from 2019 to 2017 was 1.45 in the paired samples. This study emphasizes Bordetella pertussis circulation across all age groups in both low- and high-vaccine-coverage settings in Vietnam, underscoring the need for continuous and standardized surveillance for a comprehensive understanding of its epidemiology.

Kula Jilo Tache,1 Yitbarek Getachew,2 Haileleul Negussie2 1School of Veterinary Medicine, Borena University, Borena, Yabelo, Ethiopia; 2Department of Clinical Studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, Bishoftu, EthiopiaCorrespondence: Haileleul Negussie, Department of Clinical Studies, College of Veterinary Medicine and Agriculture, Addis Ababa University, P. O. Box; 34, Bishoftu, Ethiopia, Email haileleul.negussie@aau.edu.etBackground: Neosporosis is a major cause of abortion in smallholder dairy farms in Ethiopia. However, its status and impact in pastoral cattle production settings were uncovered. This study was performed with the aims of estimating the seroprevalence and associated potential risk factors for Neospora caninum in Boran cattle in Teltelle district of Borana zone, Ethiopia.Methods: 180 blood samples were collected from 48 randomly selected pastoral herds using a multistage sampling technique and subjected to an indirect enzyme-linked immunosorbent assay (ELISA) test to detect antibodies specific to N. caninum. A questionnaire survey was also used to identify the potential risk factors of N. caninum in the study area. Evaluation of the associated risk factors was conducted using a multivariable logistic regression model.Results: Antibodies against N. caninum exposure were detected in 5% of cattle (95% CI: 1.816– 8.184) from 180 animals tested. Similarly, the seroprevalence of N. caninum in herds with at least one positive animal was 14.6% (95% CI: 4.598– 24.567) from 48 herds examined. A multivariable logistic regression model identified the following as significant risk factors: a history of abortion (AOR = 23; 95% CI: 2.354– 188.702; P = 0.006), dystocia (AOR = 11; 95% CI = 22.275– 55.860; P = 0.003), wells water sources (AOR = 9; 95% CI: 1.599– 47.568; P = 0.012), and dogs fed with raw animal products (AOR = 6; 95% CI: 11.213– 27.222; P = 0.028).Conclusion: This study revealed the first serological evidence of N. caninum exposure in cattle reared under pastoral production system. Our findings suggest N. caninum is likely to be an important cause of abortion and dystocia in cattle in Ethiopia. Management practices, such as provision of hygienic water and restriction of dogs fed with raw animal products, are likely to reduce the risk of infection. Thus, maximizing community awareness about these disease management practices is suggested.Keywords: abortion, cattle, ELISA, Neospora caninum, pastoral, seroepidemiology

ABSTRACT: Objectives: To evaluate class suspension and mass vaccination implemented among Taipei schoolchildren during the 2009 influenza pandemic and investigate factors affecting antibody responses. Methods: We conducted 2 cohort studies on: (1) 972 schoolchildren from November 2009–March 2010 to evaluate pandemic policies and (2) 935 schoolchildren from November 2011–March 2012 to verify factors in antibody waning. Anti-influenza H1N1pdm09 hemagglutination inhibition antibodies (HI-Ab) were measured from serum samples collected before vaccination, and at 1 and 4 months after vaccination. Factors affecting HI-Ab responses were investigated through logistic regression and generalized estimating equation. Results: Seroprevalence of H1N1pdm09 before vaccination was significantly higher among schoolchildren who experienced class suspensions than those who did not (59.6% vs 47.5%, p

The factors leading to the global emergence of Enterovirus D68 (EV-D68) in 2014 as a cause of acute flaccid myelitis (AFM) in children are unknown. To investigate potential changes in virus transmissibility or population susceptibility, we measured the seroprevalence of EV-D68-specific neutralising antibodies in serum samples collected in England in 2006, 2011, and 2017. Using catalytic mathematical models, we estimate an approximately 50% increase in the annual probability of infection over the 10-year study period, coinciding with the emergence of clade B around 2009. Despite such increase in transmission, seroprevalence data suggest that the virus was already widely circulating before the AFM outbreaks and the increase of infections by age cannot explain the observed number of AFM cases. Therefore, the acquisition of or an increase in neuropathogenicity would be additionally required to explain the emergence of outbreaks of AFM. Our results provide evidence that changes in enterovirus phenotypes cause major changes in disease epidemiology.

ABSTRACT: Leptospirosis is a zoonosis that can infect buffaloes and other mammalians, and it’s caused by Gram-negative bacteria of the genus Leptospira spp. The infection occurs through contact with urine or a contaminated environment with the mucous membranes of the animals, and the disease has two phases: leptospiremia and leptospiruria. The objective of this study was to determine the frequency of leptospirosis in buffaloes in the state of Paraná, Brazil, as well as the main serovars present in this area. A total of 276 blood samples were collected from buffaloes from 18 properties located in different cities and mesoregions of Paraná state. A microscopic agglutination test (MAT) was performed to detect the presence of anti-Leptospira spp. antibodies and to identify its serovars. The prevalence was 77.17% (213/276) of buffaloes seropositive for at least one serovar. The most frequent serovar was Icterohaemorrhagiae, followed by the Pomona serovar and serovar Hardjo. This study seems to be the first to determine the frequency of buffaloes with leptospirosis in the state of Paraná. Prevention and control measures are important to control the disease in herds.

Background: Due to the unclear protective role of produced antibodies and the need for seroepidemiologic studies, we surveyed the COVID-19 seroprevalence among healthcare professionals who had direct or indirect contact with COVID-19 patients. Methods: From 19 October 2020 to 17 February 2021, 300 healthcare workers were enrolled and tested for serum antibodies in this prospective cohort study. Demographic information, risk factors, and infection history were collected. Anti- SARS-CoV-2 IgG and IgM antibody titers were determined to estimate the seroconversion rate. Results: During the first and second phases of the study, the positive seroconversion rates were 31.7 and 26.6%, respectively. In seronegative individuals, sixteen (10.6%) new cases of COVID-19 and five (6.3%) reinfections were identified. Among those with a positive antibody level, forty-one (36.9%) healthcare workers reported no symptoms in the preceding months. There was no association between occupational exposure and an increased probability of seroconversion. Conclusions: The seropositivity rate and the rate of asymptomatic individuals with seroconversion was remarkable and could be an indicator of a high infection rate among healthcare workers. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) is a major public health concern worldwide. However, infection levels are rarely known, especially in Africa. We recruited individuals from Ouagadougou, Burkina Faso and Lambaréné, Gabon (age range, 1–55 years), tested their blood for CHIKV antibodies, and used serocatalytic models to reconstruct epidemiological histories. In Ouagadougou, 291 of 999 (29.1%) individuals were seropositive, ranging from 2% among those aged <10 years to 66% in those aged 40–55 years. We estimated there were 7 outbreaks since the 1970s but none since 2001, resulting in 600 000 infections in the city, none of which were reported. However, we could not definitively conclude whether infections were due to CHIKV or o'nyong-nyong, another alphavirus. In Lambaréné, 117 of 427 (27%) participants were seropositive. Our model identified a single outbreak sometime since 2007, consistent with the only reported CHIKV outbreak in the country. These findings suggest sporadic outbreaks in these settings and that the burden remains undetected or incorrectly attributed. [ABSTRACT FROM AUTHOR]

Background: Chile has achieved the highest coverage for vaccines against the SARS-CoV-2 virus worldwide. Objective: To assess the progression of immunity (natural and acquired by vaccine) in a cohort from two Chilean cities. Methods: Individuals (n = 386) who participated in three phases of population-based serial prevalence studies were included (2020–2021 and 2022). Presence of SARS-CoV-2 antibodies was measured in serum. Data including time of vaccination and type of vaccine received were analysed with descriptive statistics. Results: Seroprevalence was 3.6% in the first round and increased to 96.9% in the second and 98.7% in the third. In the third round, 75% of individuals who had received the basal full scheme were seropositive at 180 days or more since their last dose; 98% of individuals who received one booster dose were seropositive at 180 days or more, and 100% participants who received two boosters were seropositive, regardless of time since their last dose. Participants receiving mRNA vaccines had higher seroprevalence rates over time. Conclusions: The high vaccination coverage in Chile enabled the population to maintain high levels of antibodies. Vaccination boosters are essential to maintain immunity over time, which also depends on the type of vaccine administered. [ABSTRACT FROM AUTHOR]

Objective: Since the resumption of face-to-face education in October 2020, which was suspended due to the COVID-19 pandemic, coincides with the period when SARS-CoV-2 infection rates in young adults are on the rise. This study focuses on the 2019 corona virus outbreak in young adults, the largest link in the chain of transmission, which can be defined as silent contagious agents. It is aimed to provide epidemiological data by detecting virus disease (COVID-19) seropositivity with two different serological methods, and to evaluate the symptom-test performance relationship of asymptomatic/mild symptom/symptomatic cases. Methods: A cross-sectional study was conducted with students studying at Cappadocia University health programs between December 2020 and February 2021 and who will attend practice courses face-to-face. Participants were surveyed about their COVID-19 symptoms and disease histories based on SARS-CoV-2 exposure. For SARSCoV-2 antibody detection, blood samples were taken from the participants and investigated with a single lateral flow immunoAssay (LFIA, Novatech, Turkey) cassette test. The samples with positive test result were then SARS-CoV-2 Anti-N IgM+IgG; SARS-CoV-2 Anti-S IgM+IgG; SARS-CoV-2 Anti-RBD IgG; It was re-evaluated using the electrochemiluminescence immunoassay (ECLIA) method with the anti-SARS-CoV-2 kit (Roche, Germany). Results: Of the 239 samples participating in the study, 50 (20.9%) samples that were positive for SARS-CoV2 IgM/IgG according to the LFIA method were then studied again with the ECLIA method. According to the ECLIA result, 72% (36/50) of individuals against both nucleocapsid (N) and spike (S) antigens, and 70% (35) against RBD antigen were seropositive. Based on the ECLIA test results, 239 samples were studied and 50 samples were found to be IgM/IgG positive, with a sensitivity of 64% and a specificity of 93%. Contingence history was reported in 46% (n=23) of patients who were seropositive by both methods, while 30% (n=15) showed a COVID-19 clinic. Fifty four percent (n=27) of the participants reported that they did not have a PCR (polymerase chain reaction) test, but antibody response was observed in all of them. Only 28% (n=14) of seropositive patients reported positive PCR results, and 4% of them stated that they had a chronic disease. It will be important to continue to observe the serological status of young people, particularly in the context of new COVID-19 variants and in the low interest in mass vaccination campaigns targeting young people. Conclusion: It is thought that the performance of ECLIA with rapid casette test does not have a good degree of agreement and confirmation with different immunoassay tests would be more useful for epidemiological surveillance. Especially the new COVİD-19 in the context of the variants and targeting youth due to the lack of interest in vaccination champaigns continue to monitor the serological status of young people it will be important. [ABSTRACT FROM AUTHOR]

School closures were enforced as measures to restrain the COVID-19 pandemic, based on the assumption that young children may play a key role in SARS-CoV-2 spread. This study aims to determine the prevalence of SARS-CoV-2 IgG antibodies in children and corresponding parents, in order to improve surveillance and estimate the prevalence of asymptomatic or subclinical COVID-19 cases. A prospective multicenter study was conducted between March and June 2021 in Greece. Children admitted to the hospital or examined in outpatient clinics for reasons other than COVID-19 and their parents were tested for anti-Spike SARS-CoV-2 IgG in serum. A questionnaire about clinical and demographic data was completed. The study included 823 participants: 427 children and 396 corresponding parents. The overall seroprevalence was 16.4% in parents and 13.8% in children. Among families with ≥ 1 seropositive child or parent, the combination of a seropositive parent and a corresponding seronegative child was 29.6%, a seronegative parent and a corresponding seropositive child was 24.7%, and a seropositive child with a corresponding seropositive parent was 45.7%. Age, level of education, and school or work attendance were not significantly associated with increased seropositivity. On the contrary, ethnic minority of Roma, close contact with known COVID-19 case, previous symptoms consistent with COVID-19, and mass gatherings were risk factors for seropositivity. Conclusion: The spread of SARS-CoV-2 during a period of lockdown in Greece was low in children and comparable to adults most likely due to intrafamilial transmission. Accordingly, it is unlikely that children have boosted virus transmission. What is Known: • In the earliest months of the pandemic, it was demonstrated that children had significantly lower seroprevalence rates than the older age groups, due to the fact that children had decreased exposure to the virus, because of early public health interventions, such as school and day care closure. • Later, further studies reported that children have similar incidence rate of SARS-CoV-2 infection compared to adults in households and community settings. What is New: • In this seroprevalence study, the spread of SARS-CoV-2 infection during a period of lockdown in Greece with the predominance of the Alpha-variant was particularly low in children and comparable to adults, most likely due to intrafamilial transmission. • These study findings will be useful for decisions regarding non-pharmaceutical interventions during the pandemic, and especially, to guide in designing and implementing appropriate containment measures for schools and social gatherings. [ABSTRACT FROM AUTHOR]

Background and Aim: Hydatidosis is an important parasitic disease, caused by the larval stage of Echinococcus granulosus. It is a major health problem in different parts of the world including Iran. The disease can lead to serious complications in several organs, especially in liver and lungs. It seems that the military forces have a high risk of infection due to their presence in different missions in various climatic, geographical, and security conditions. This study aimed at determining the sero-prevalence of hydatidosis in the personnel of a military unit. Methods: During a cross-sectional study conducted in 2020, antigen B (AgB) was prepared from sheep hydatid cyst fluid (HCF) by Oriol method. Two hundred and five sera samples were prepared and evaluated by AgBELISA. Results: Out of 205 examined samples, 30 cases (14.6%) showed a positive response by AgB-ELISA. The most positive cases were observed in personnel aged 30-39 years (63.3%), working in the operational category (76.7%), with 11-20 years of service (43.3%), with university education (96.7%) and living in urban areas (80%). Furthermore, individuals consuming spring/boiled/mineral water (53.3%), who used salt and vinegar (50%) to wash vegetables, had the highest percentage of seropositivity. According to the statistical analysis, there was no significant relationship between the variables and the positivity of AgB-ELISA (P>0.05). Conclusion: High sero-prevalence of antibodies (IgG) against AgB of hydatid cyct in military forces demonstrated the importance of high-quality health educational programs in such communities. Screening and following up of the persons with positive sera are also recommended. [ABSTRACT FROM AUTHOR]

The incidence of hepatitis A virus (HAV) infection has declined significantly worldwide, including in Japan. A nationwide seroepidemiological study on hepatitis A in Japan has taken place almost every 10 years since 1973, and the last study was performed in 2003. In the present study, we describe the latest seroepidemiological pattern of hepatitis A in Japan using 7867 serum specimens obtained from healthy individuals collected between 2013 and 2017, approximately 10 years after the last study. Among them, 223 were anti‐HAV positive. About 68% of individuals aged 60 years and older had anti‐HAV antibodies, whereas only 1.1% of those aged below 60 years old had immunity; thus, almost all individuals younger than 60 years of age were HAV susceptible. In comparison with previous investigations, the susceptible population has increased and aged. According to data from the National Epidemiological Surveillance of Infectious Diseases (NESID) program, between 1989 and 2016, the proportion of patients with hepatitis A aged 60 years and older continuously increased with each year. The NESID data also suggested that recently, typical large foodborne outbreaks of hepatitis A have become rare, and cases tend to be reported among at‐risk groups; overseas travelers contributed to 25% of hepatitis A cases, and in 2018, the first nationwide hepatitis A outbreak that affected mostly men who have sex with men was reported. The purpose of this study was to determine the current status of HAV infection in Japan, based on both seroepidemiology and the national surveillance data from the NESID. [ABSTRACT FROM AUTHOR]

Costa Rica harbors several flaviviruses, including Dengue (DENV), Zika (ZIKV), West Nile virus (WNV), and Saint Louis encephalitis virus (SLEV). While DENV and ZIKV are hyperendemic, previous research indicates restricted circulation of SLEV and WNV in animals. SLEV and WNV seroprevalence and high transmission areas have not yet been measured. To determine the extents of putative WNV and SLEV circulation, we sampled peri-domestic and domestic animals, humans, and mosquitoes in rural households located in two DENV and ZIKV hyperendemic regions during the rainy and dry seasons of 2017–2018 and conducted plaque reduction neutralization test assay for serology (PRNT) and RT-PCR for virus detection. In Cuajiniquil, serological evidence of WNV and SLEV was found in equines, humans, chickens, and wild birds. Additionally, five seroconversion events were recorded for WNV (2 equines), SLEV (1 human), and DENV-1 (2 humans). In Talamanca, WNV was not found, but serological evidence of SLEV circulation was recorded in equines, humans, and wild birds. Even though no active viral infection was detected, the seroconversion events recorded here indicate recent circulation of SLEV and WNV in these two regions. This study thus provides clear-cut evidence for WNV and SLEV presence in these areas, and therefore, they should be considered in arboviruses differential diagnostics and future infection prevention campaigns. [ABSTRACT FROM AUTHOR]

Abstract Background HIV infection is associated with an increased risk of morbidity and mortality from vaccine preventable infections. This research describes, in the context of changing patient demographics, the seroprevalence of vaccine preventable viral infections among attendees of the largest centre for HIV positive patients in Ireland. Methods Baseline serum IgG results for measles, mumps, rubella, varicella zoster virus (VZV) & hepatitis A, as well as hepatitis B sAg, cAb and sAb results, were retrieved for 2534 clinic attendees attending in 2018. Results were available for between 990 and 2363 attendees (39–93%), depending on the test, and were compared with 2013 clinic data. Results There was a 35% increase in attendees in 2018 when compared to 2013. The largest increase was in attendees of South American origin. In 2018, males accounted for 73% of the entire cohort and the HIV acquisition risk for 48% of attendees was MSM. 47% of attendees were originally from Ireland. Among those tested, 33% were susceptible to at least one component of the MMR vaccine. 5% were VZV non-immune (significantly associated with younger age and the acquisition risk status of injection drug use). 21% were hepatitis A non-immune (significantly associated with younger age and being of European or South American origin). 32% were hepatitis B cAb seropositive (significantly associated with older age, injection drug use status and being originally from Africa). 3% demonstrated hepatitis B sAg positivity. 64% had hepatitis B sAb ≥ 10mIU. Conclusion In a cohort of attendees to an HIV clinic in a large urban setting, the susceptibility to several common vaccine preventable viral infections, in particular MMR and hepatitis A and B, was high. These results highlight the importance of proactive screening and immunisation to help protect this high risk patient group against vaccine preventable diseases.

Abstract Background Gyrovirus homsa1 (GyH1) (also known as Gyrovirus 3, GyV3) is a non-enveloped, small, single-stranded DNA virus, which was first identified in children with acute diarrhea, and was subsequently detected in marketed chickens, broilers with transmissible viral proventriculitis (TVP), and mammals. GyH1 is a pathogenic virus in chickens, causing aplastic anemia, immunosuppression, and multisystem damage. However, the seroepidemiology of GyH1 infection in chickens remains unclear. Here, we investigated the seroprevalence of GyH1 in chickens by ELISA to reveal the endemic status of GyH1 in China. Results An indirect ELISA with high sensitivity and specificity was developed for investigation of seroepidemiology of GyH1 in chickens in China. The seropositive rate of GyH1 ranged from 0.6% to 7.7% in thirteen provinces, and ranged from 4.1% to 8.1% in eight species chickens. The seropositive rate of GyH1 in broiler breeders was significantly higher than that of in layers. There was a negative correlation between seropositive rate and age of chickens. The highest and lowest seropositive rate were present in chickens at 30–60 days and over 180 days, respectively. Conclusions The seroepidemiological investigation results demonstrated that natural GyH1 infection is widespread in chickens in China. Different species showed different susceptibility for GyH1. Aged chickens showed obvious age-resistance to GyH1. GyH1 has shown a high risk to the poultry industry and should be highly concerned.

Rationale. Hepatitis E (HE) is a zooanthroponosis. Domestic pigs are the main reservoir for hepatitis E virus (HEV) in the Republic of Belarus (RB). Considering the well-developed pig farming, there is a high risk of infection spread among the population; however, the scale of virus circulation and patterns of HE epidemiology in the above region are still insufficiently explored.The aim of the study is to assess HEV seroprevalence specific for the HE epidemic process in RB.Materials and methods. Serum samples (n = 2,784) collected from patients of infectious disease departments at hospitals (n = 1,669) and relatively healthy people (n = 1,114) from different RB regions were used to measure the activity of alanine aminotransferase (ALT) by a kinetic rate method as well as IgG antibodies to HEV by the enzyme-linked immunosorbent assay (ELISA).Results. In the group of healthy people, anti-HEV IgG were detected in 7.3% (95% CI, 5.8–9.0). In the group of patients with liver disorders, the detection frequency was significantly higher, reaching 11.2% (95% CI, 9.6–12.9). In the groups of healthy people and patients with elevated ALT levels, the HEV seroprevalence did not depend on their gender or the region of residence. The anti-HEV IgG detection frequency gradually increased among olderage patients and reached the peak levels (15.9% on average) in the over-64 age group.Conclusions. RB is characterized by intensive HEV circulation, while the HE epidemic process is characterized by a latent nature. The actual prevalence of HЕ seromarkers among the RB population exceeds the frequency of diagnosed cases, suggesting insufficient vigilance of healthcare workers towards HE and subclinical forms of infection in most of the patients.

Background and purpose: Recently, due to the reduction of hepatitis A in Iran there are people with low or no Hepatitis A Virus- Antibody (HAV-Ab), therefore, people at Arbaeen Pilgrimage are at risk for hepatitis A. This study aimed at examining HAV-Ab in pilgrims traveling from Mazandaran province, Iran to Karbala in 2018. Materials and methods: This cross-sectional study was performed in 200 people selected from 40,000 pilgrims in Mazandaran province. Serum samples were evaluated for presence of HAV-Ab and data for demographic characteristics and history of hepatitis A immunity were recorded. Data analysis was performed in SPSS V16. Results: The participants were 137 (68.5%) males and 63 (31.5%) females. Positive and negative HAV-Ab were seen in 156 (78%) and 44 (22%), respectively. Mean ages of people with positive and negative HAV-Ab were almost similar (50 years and 47 years, respectively). HAV-Ab status was found to be significantly associated with job (P0.05). Conclusion: Twenty-two percent of people who were travelling to Karbala had no HAV-Ab, which is significant because the risk of developing fulminant hepatitis increases in adults, therefore, vaccination of Karbala pilgrims for hepatitis A virus is suggested.

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is a neglected tropical disease with life-threatening implications. In this study, we conducted a seroepidemiological survey to determine the prevalence and clinical profiles of CD in 217 individuals from an impoverished rural community in Southern Bahia, Brazil. The overall prevalence of CD in the studied community was 0.92%, detected through latent class analysis (LCA). Two individuals tested positive for anti-T. cruzi IgG, both being male farmers. One case was a 22-year-old man born in Camamu, with no evidence of congenital transmission, suggesting other routes of transmission such as vector-borne transmission due to migratory activities. The other case was a 69-year-old man born in São Felipe, who had lived in an adobe/brick house and had a pacemaker due to cardiac involvement caused by CD. The prevalence in this community was lower than expected, given the socioeconomic conditions and environmental factors that contribute to T. cruzi transmission. This could be attributed to the implementation of preventive measures and vector control programs by the Brazilian Government. However, continuous monitoring and surveillance are essential to sustain control efforts and detect any potential re-emergence of the disease. While the overall prevalence was low, the detection of positive cases underscores the need for continued surveillance and control measures in vulnerable populations, such as rural communities. Active surveillance, early diagnosis, and timely treatment are crucial in preventing disease progression and complications, thereby enhancing the effectiveness of screening and treatment programs.

Background and Objective:Hydatidosis is one of the most important zoonotic infections that is a health-economic concern in endemic areas. This study aimed to determine the seroprevalence of hydatidosis in Arak, Iran. Materials and Methods:This descriptive cross-sectional study was conducted on 456 individuals attending health centers in Arak in 2020. Blood samples were taken from the subjects and tested for anti-Echinococcus antibodies by the enzyme-linked immunosorbent assay-immunoglobulin G test. The collected data were then analyzed. Results:It was revealed that 6 out of 456 subjects had anti-Echinococcus antibodies (1.3%, 95% confidence interval: 0.3-2.3) The mean age of the participants was 58.8±19.9 years, and frequencies of seropositive individuals were 1.6% and 1% in men and women, respectively. Moreover, 5 (1.4%) and 1 (1%) urban and rural residents were found seropositive, respectively. According to the results, 93.4% of the participants were unaware of hydatid cyst disease and 21.5% of the cases had contact with dogs (P

Background and Aim: Neospora caninum is one of the most common infectious organisms worldwide that causes abortion in cattle. To the best of our knowledge, no previous studies have focused on N. caninum infection in the local Atlas brown cattle from Northeast Algeria. This study aimed to assess the importance of bovine neosporosis for causing abortion in Atlas brown cattle and to identify selected risk factors. Materials and Methods: A case-control study was performed on 60 control farms and 30 case farms. We collected 650 blood samples from 650 pregnant cows from 90 farms in five Algerian provinces; Jijel, Skikda, Annaba, El-Tarf, and Souk- Ahras. Sera samples were analyzed for the presence of antibodies against N. caninum using enzyme-linked immunosorbent assays. Results: The seroprevalence of N. caninum infection in the cows was 36.2% (95% confidence interval [CI]: 32.7-39.8) and in the farms was 81.1% (95% CI: 73.0-89.2). Risk factors found by multivariable logistic regression included: Presence of dogs (odds ratio [OR] 4.7, 95 CI 2.9-7.3); age ≥84 months (OR 4.9, 95 CI 2.8-8.3); Jijel region (OR 2.2, 95 CI 1.1-4.5); white (OR 2.5, 95 CI 1.4-4.4) and gray (OR 2.5, 95 CI 1.4-4.5) coat; moderate (OR 2.30, 95 CI 1.4-3.8) and bad (OR 3.1, 95 CI 1.8-5.3) hygiene; and second (OR 2.5, 95 CI 1.4-4.4); and last (OR 2.3, 95 CI 1.3-4.2) stage of pregnancy. Our case-control study showed no significant association between seropositivity of N. caninum and abortion at the farms level (OR 0.9, 95 CI 0.3-2.7). Similarly, there was no significant association between seropositivity of N. caninum and abortion at the individual level (OR 0.8, 95 CI 0.6-1.2). Conclusion: This is the first study of N. caninum infection in pregnant local cows from Northeast Algeria. The prevalence rate of antibodies against N. caninum was high. Almost all risk factors studied for infection were significantly associated with seroprevalence. Our analysis showed no relation between N. caninum infection and abortion. Consequently, these local cows are resistant to abortion caused by N. caninum.

Wallabies and other marsupials are highly susceptible to Toxoplasma gondii. In this study, 26 macropod samples were collected (8 red kangaroos, 4 Parma wallabies, 8 red-necked wallabies, 5 albino red-necked wallabies and 1 Eastern grey kangaroo), including tissue (n = 9) and serum (n = 17) samples. According to the modified agglutination test (MAT) results (cutoff 1:25), 50% (95% Cl: 32.06–67.94%) of the macropods had T. gondii antibodies. Among them, species, survival state, and sampling date were risk factors for T. gondii susceptibility (P

Background: Visceral leishmaniasis (VL) also known as Kala-azar is considered as one of the zoonotic infections in Mediterranean countries. The reservoir of this infection is dogs and sand flies are considered as its vectors. Due to reported sporadic cases of Kala-azar in the past five years in Shahroud County, Semnan Province, Iran, this study aimed to investigate the status of this infection in this area and to determine its seroepidemiology to take required measurements for infection control and treatment. Methods: This descriptive cross-sectional study was conducted on 504 subjects residing in seven villages in Shahroud County, Semnan, Iran. Samples were randomly selected using the cluster sampling method and blood samples were collected from subjects aged up to 13 years old (90%) and adults over 13 years old (10%) from September 2018 to May 2019. After separating sera from whole blood, samples were subjected to direct agglutination test (DAT) to detect anti-Leishmania infantum antibodies. First dilutions were prepared from 1:10 to 1:800 for human samples. Results: Results of serological testing with 1:800 titration indicated that no sample was positive for antibody against Leishmania infantum. After secondary screening, 10 cases (1.98%) showed the antibody titer of 1:100, while four cases (0.79%) showed the antibody titer of 1:400. According to clinical findings, no patient was suffering from fever, weight loss, splenomegaly, hepatomegaly, and cachexia and therefore did not show the symptoms of Kala-azar. Conclusion: The results of the current study indicate that Kala-azar is not prevalent in Shahroud County.

• A longitudinal serosurveillance of measles was conducted in Japan from 2003 to 2020. • Measles seroprevalence increased in the process to measles elimination. • The measles antibody titer decreased after measles elimination. • The effective reproduction number became higher toward measles elimination. • Measles resurgence due to waning immunity is an issue after the COVID-19 pandemic. Japan is one of the countries conducting longitudinal serosurveillance of vaccine-preventable diseases. We conducted surveillance of the local measles-specific antibody titer, calculated the effective reproduction number (R e), and compared data of four terms: term 1, 2003–2006 (before the introduction of the second shot of measles-containing vaccine); term 2, 2007–2010 (early term toward measles elimination); term 3, 2011–2014 (later term toward measles elimination); and term 4, 2015–2020 (after elimination of measles in Japan). Approximately 250 sera from volunteers aged 0 to ≥ 40 years were collected and examined for measles-specific IgG using the gelatin particle agglutination (PA) method annually from 2003 to 2020. Seroprevalence and the geometric mean of the PA antibody titer were examined by term. R e was calculated using the age-dependent proportion immune and contact matrix for each term. Of the 4,716 sera, 886 in term 1, 1,217 in term 2, 1,069 in term 3, and 1,544 in term 4 were collected. The seroprevalence gradually increased from term 1 (88.3% CI 86.0–90.3) to term 4 (95.7% CI 94.6–96.7), and the seroprevalence of term 1 was significantly lower than those of other terms (Fisher's exact test, p < 0.001), with PA titer ≥ 16 as positive. By contrast, PA antibody titers significantly decreased from term 1 (median 1,024) to term 4 (median 256) (Mann–Whitney U test, p < 0.001). With the protection level (PA titer ≥ 128 and ≥ 256) as positive, R e gradually increased from term 1 (1.8 and 2.3) to term 4 (2.5 and 4.8, respectively). Waning levels of measles antibodies potentially increase the measles susceptibility in Osaka, Japan. This trend might imply a limitation of vaccine-induced immunity in the absence of a natural booster for wild strains after measles elimination. This study provides a cue for maintaining continuous measles elimination status in the future. [ABSTRACT FROM AUTHOR]

Background and Aim: Toxoplasmosis is a common parasitic infection that can endanger mother's and neonates' health during pregnancy. The disease is also prevalent in Iran. This study intended to evaluate the seroepidemiology of toxoplasmosis in neonates and postpartum mothers referred to health centers of Yazd in Iran in 2020. Materials and Methods: Totally, 184 postpartum mothers and 184 neonatal umbilical cords in health centers of Yazd were evaluated for Toxoplasma infection through a specific IgM and IgG antibodies kit. The obtained data were analyzed by SPSS18. Results & Conclusion: Out of 184 samples of postpartum mothers, 8 cases (4.35%) were seropositive, and 176 (95.65%) were seronegative for IgG antibody; moreover, 7 cases (3.80%) were seropositive, and 177 (96.20%) seronegative for IgM antibody. Also, 184 neonatal umbilical cords were IgM negative, and no toxoplasmosis infection was reported. No significant correlation was found between seroprevalence of Toxoplasma infection and caring for pets, consumption of raw meat, level of education, blood type, job, living area and type of delivery (P>0.05). However, a significant correlation was identified between the number of deliveries and the prevalence of toxoplasmosis (P=0.014). This study also illustrated a low prevalence of Toxoplasma infection in postpartum mothers and no congenital transmission of the disease in diverse health centers of the province. However, there was no statistically significant relationship between risk factors and the prevalence of Toxoplasma. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the seroprevalence of Bordetella pertussis and persistence of antibodies following vaccination. We recruited 6060 healthy subjects from five provinces of China during 2017-2018. Serum IgG antibodies against pertussis toxin (anti-PT IgG) and filamentous hemagglutinin (anti-FHA IgG), and serum IgA antibodies against pertussis toxin (anti-PT IgA) were measured by ELISA. Geometric mean concentration (GMC), seropositivity rate, and recent infection rate were calculated. Among 0-6 years-olds, the anti-PT IgG, anti-PT IgA, and anti-FHA IgG GMCs were 6.4 IU/ml (95% CI 6.1-6.8), 2.8 IU/ml (95% CI 2.7-2.8), and 13.3 IU/ml (95% CI 12.4-14.2), respectively. The anti-PT IgG GMC increased in accordance with the primary vaccination series (4-6 months) and the toddler booster (18-24 months), but declined thereafter through to age 5 years [4.7 IU/ml (95% CI 4.2-5.4)]. The seropositivity rate of pertussis in >6 year-olds was 9.0% (95% CI 8.1-9.9) and the recent infection rate was 3.3% (95% CI, 2.7-3.8). Recent infection rate began to increase from 6 years of age, with peaks at 9, 20, 40, and ≥60 years of age. The anti-PT IgG GMCs of children aged 0-6 years who were vaccinated with DTaP, DTaP-IPV//PRP～T, and DTaP-Hib were 5.9 IU/ml (95% CI 5.6-6.3), 20.7 IU/ml (95% CI 15.6-27.8), and 11.7 IU/ml (95% CI 7.5-18.1) ( p  < .001), respectively ( p  < .001). Pertussis vaccination improves anti-PT IgG levels, however these wane soon after vaccination. Sero-estimated recent infection rates appear to increase from school age into adolescence and adulthood. Pertussis vaccine boosters should be considered in these age groups.

This study employed sero-epidemiological methods to estimate the incidence of pertussis within a healthy population located in eastern China. The aim was to gain deeper insights into the epidemiological characteristics and burden of pertussis within the country. Blood samples were collected from healthy individuals in Jiangsu Province between June 2019 and December 2022. The levels of IgG antibodies against pertussis toxin (anti-PT) and filamentous hemagglutinin (anti-FHA) in the serum were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). Additionally, pertussis case data reported in Jiangsu Province were collected from the China Information System for Disease Control and Prevention and compared with the results of this study. In 2022, the reported incidence of pertussis stood at 1.0 per 100,000 individuals, marking the highest rate observed in the past two decades. Among 1,909 patients examined, the geometric mean concentration (GMC) of anti-PT IgG antibody was 20.2 (18.5-21.9) IU/ml, while that of anti-FHA IgG antibody was 27.0 (25.4-28.7) IU/ml. The IgG-PT and IgG-FHA seropositivity rate (>20.0 IU/ml) was highest in the 1 ~ 2 y old group and decreased rapidly to the lowest in the 3 ~ 4 y old group and then increased gradually with age. The estimated rate of pertussis infection based on seroprevalence was approximately 25,625-fold higher than the reported notification rate in the ≥15 year age group. Our findings highlight decreased immunity post-vaccination, stressing the importance of additional booster shots for adolescents and adults to maintain immunity and reduce severe illness. Additionally, they offer vital guidance for policymakers to enhance immunization strategies.

We present a review and primer of methods to understand epidemiological dynamics and identify past exposures from serological data, referred to as serodynamics. We discuss processing and interpreting serological data prior to fitting serodynamical models, and review approaches for estimating epidemiological trends and past exposures, ranging from serocatalytic models applied to binary serostatus data, to more complex models incorporating quantitative antibody measurements and immunological understanding. Although these methods are seemingly disparate, we demonstrate how they are derived within a common mathematical framework. Finally, we discuss key areas for methodological development to improve scientific discovery and public health insights in seroepidemiology., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: James Hay reports financial support was provided by Wellcome Trust. Saki Takahashi reports financial support was provided by Bill & Melinda Gates Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory infections and hospitalization in infants and the elderly. Newly approved vaccines and the prophylactic antibody nirsevimab have heightened interest in RSV immunologic surveillance, necessitating the development of high-throughput assays assessing anti-RSV neutralizing activity. Quantitative viral neutralization remains the best correlate of protection for RSV infection and the gold standard for RSV immunological testing. Here, we developed a high-throughput RSV strain A2 focus-reduction neutralization test validated to Clinical Laboratory Improvement Amendments (CLIA)/ Good Clinical Laboratory Practices (GCLP) standards using both clinical specimens and commercially available reference sera. The assay is highly accurate, generating reference serum neutralizing titers within twofold of established assays, with an analytical measurement range between 8 and 1,798 international units per mL (IU/mL). Neutralizing activity measured by the assay strongly correlated with antibody titer determined via indirect enzyme-linked immunosorbent assay (ELISA) ( ρ = 1.0, P = 0.0014). Individuals recently having tested positive via quantitative reverse transcription polymerase chain reaction (RT-qPCR) for RSV had a 9.1-fold higher geometric mean neutralizing titer relative to RSV PCR negatives ( P -value = 0.09). The validated assay was then used to investigate the immunity debt hypothesis for resurgent RSV outbreaks in the 2022-2023 season, using adult clinical remnant sera sent for herpes simplex virus (HSV)-1/2 antibody testing. There was no difference in geometric mean anti-RSV neutralizing titers between sera sampled before and after the 2022-2023 RSV outbreak ( P = 0.68). These data are consistent with limited changes in RSV-neutralizing antibody levels in adults across the 2022-23 RSV outbreak., Importance: Population surveillance studies of serum-neutralizing activity against RSV are crucial for evaluating RSV vaccine efficacy and vulnerabilities to new strains. Here, we designed and validated a high-throughput assay for assessing anti-RSV neutralizing activity, standardized its measurements for comparison with other methodologies, and demonstrated its applicability to real-world samples. Our assay is precise, linear, and yields measurements consistent with other standardized assays, offering a methodology useful for large-scale studies of RSV immunity. We also find no significant difference in neutralizing titers among adults between those taken before and after large RSV outbreaks associated with the latter stages of the coronavirus disease of 2019 (COVID-19) public health emergency, underlining the need for a greater understanding of the dynamics of serological responses to RSV infection.

Background: Cystic Echinococcosis is considered a cosmopolitan cyclozoonotic parasitic infection. This study aimed at evaluating the seroprevalence of human hydatidosis using ELISA test and find the role of mutable factors such as age, sex, occupation, residency in the broadcast of the parasites in rural Ardabil Province, North-West of Iran. Methods: The study population was 950 asymptomatic individuals selected randomly from urban and rural populations of Ardabil province, North-West of Iran by randomized cluster sampling in 2019-2020. Immunoglobulin G antibodies against Echinococcus granulosus spp. were analyzed by ELISA test. Data were analyzed using SPSS software and Multivariable logistic regression model. Results: Overall, 42 (4.4%) of the participants had anti E. granulosus antibodies in this region. High titer antibodies were most prevalent in people age group of >70 yr old, rural areas, females and people having history of contact with dog that showed significant difference. There was no significant association between the presence of Echinococcus antibodies and sex, occupation, having history of eating unwashed vegetable. Conclusion: This is the first description of the seroprevalence of E. granulosus infection in the population in Ardabil Province, North-West of Iran. Obtained rate of hydatidosis approves the importance of diagnosing human cystic echinococcosis in these regions and it is expected that the authorities be careful to screen the disease.

Background and purpose: The actual prevalence of Coronavirus Disease 2019 (COVID-19) can only be estimated by population-based serological examinations and individuals without clinical symptoms may not be identified or reported. In this sero-epidemiological study we aimed at exploring the serum prevalence of COVID-19 in highly exposed occupational groups in western Iran. Materials and methods: A total of 1106 people with jobs with a high potential for exposure to COVID-19 (excluding doctors) were selected in Sanandaj, Kermanshah, and Hamedan. Demographic information of all participants were recorded and venous blood samples (3 ml) were taken. IgG levels were measured to determine the serum prevalence of immunoglobulin using EUROIMMUN kit. Results: Until 15 November 2020, IgG antibody was detected positive in 317 people (28.7%). In Sanandaj, Hamedan, and Kermanshah there were 132 (32%), 88 (26%), and 99 (27.3%) people with IgG-positive antibodies, respectively. There were no significant differences in rates of positive COVID-19 IgG antibody between the cities (P= 0.158). Among individuals with IgG antibody positive (n=317), 35.4% were asymptomatic and only 3.2% were admitted to hospital because of COVID-19. Conclusion: High prevalence of COVID-19 antibodies in people with working activities of high potential for exposure to known or suspected sources of SARS-CoV-2 and a high number of asymptomatic individuals in this group showed that appropriate personal equipment and adhering to strict rules play a critical role in limiting the disease transmission.