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Background: Scrub typhus (ST) is a life-threatening infectious disease if appropriate treatment is unavailable. Large discrepancy of clinical severity of ST patients was reported among age groups, and the underlying risk factors for severe disease are unclear. Methods: Clinical and epidemiological data of ST patients were collected in 55 surveillance hospitals located in Guangzhou City, China, from 2012 to 2018. Severe prognosis and related factors were determined and compared between pediatric and elderly patients. Results: A total of 2,074 ST patients including 209 pediatric patients and 1,865 elderly patients were included, with a comparable disease severity rate of 11.0% (95% CI 7.1%–16.1%) and 10.3% (95% CI 9.0%–11.8%). Different frequencies of clinical characteristics including lymphadenopathy, skin rash, enlarged tonsils, etc. were observed between pediatric and elderly patients. Presence of peripheral edema and decreased hemoglobin were the most important predictors of severe illness in pediatric patients with adjusted ORs by 38.99 (9.96–152.67, p<0.001) and 13.22 (1.54–113.50, p = 0.019), respectively, while presence of dyspnea and increased total bilirubin were the potential determinants of severe disease in elderly patients with adjusted ORs by 11.69 (7.33–18.64, p<0.001) and 3.17 (1.97–5.11, p<0.001), respectively. Compared with pediatric patients, elderly patients were more likely to receive doxycycline (64.8% v.s 9.9%, p<0.001), while less likely to receive azithromycin therapy (5.0% v.s 41.1%, p<0.001). Conclusion: The disease severity rate is comparable between pediatric and elderly ST patients, while different clinical features and laboratory indicators were associated with development of severe complications for pediatric and elderly patients, which is helpful for diagnosis and progress assessment of disease for ST patients. Author summary: The study investigated different clinical features and risk factors for severe disease between pediatric and elderly patients with scrub typhus. We found that significantly higher frequencies of lymphadenopathy, skin rash, enlarged tonsils, etc. were observed in pediatric patients than elderly patients. Other non-specific signs, subjective complaints, and chest radiographic abnormality were overpresented in elderly patients. Risk factors for severe disease between pediatric and elderly patients with scrub typhus were different. Presence of peripheral edema and decreased hemoglobin were the most important factors for pediatric patients, while presence of dyspnea and increased total bilirubin for elderly patients. These findings reminded medical workers to acknowledge this important difference and to adopt an age specific method in the differential diagnosis and risk assessment for scrub typhus. [ABSTRACT FROM AUTHOR]

Background: In the last decade, scrub typhus (ST) has been emerging or re-emerging in some areas of Asia, including Guangzhou, one of the most affected endemic areas of ST in China.Methods: Based on the data on all cases reported in Guangzhou from 2006 to 2014, we characterized the epidemiological features, and identified environmental determinants for the spatial distribution of ST using a panel negative binomial model.Results: A total of 4821 scrub typhus cases were reported in Guangzhou during 2006-2014. The annual incidence increased noticeably and the increase was relatively high and rapid in rural townships and among elderly females. The majority of cases (86.8%) occurred during May-October, and farmers constituted the majority of the cases, accounting for 33.9% in urban and 61.6% in rural areas. The number of housekeeper patients had a rapid increment in both rural and urban areas during the study period. Atmospheric pressure and relative humidity with lags of 1 or 2 months, distributions of broadleaved forest and rural township were identified as determinants for the spatiotemporal distribution of scrub typhus.Conclusion: Our results indicate that surveillance and public education need to be focused on the elderly farmers in rural areas covered with broadleaf forest in southern China. [ABSTRACT FROM AUTHOR]

• All individual complications including shock, ARDS, meningitis and acute kidney injury were found to be significantly associated with treatment failure and time to defervescence, after adjusting for the effects of age, sex, initial antibiotic type, and interval from symptom onset to start of antibiotic treatment. • Treatment failure risk was higher for azithromycin than doxycycline for patients with meningitis; and treatment failure risk was higher for chloramphenicol than doxycycline for patients with acute kidney injury, pneumonia or shock. • Antibiotic resistance occurred in 2.4% of doxycycline group, 6.3% of azithromycin group and 10.4% of chloramphenicol group. Deaths occurred in 29.4% (5/17), 0% (0/5) and 10.0% (1/10) of patients, respectively, with no significant differences between groups (P =0.232). Previous studies have evaluated treatment efficacy of various antibiotics for patients with mild-to-moderate scrub typhus (ST). However, the efficacy of different antibiotics for treating severe ST remains uncertain. A retrospective study of patients with severe ST was undertaken in China. The treatment efficacy rates of doxycycline, azithromycin and chloramphenicol were compared, using treatment failure and time to defervescence as primary outcomes. In total, 876 patients with severe ST who initially received doxycycline, azithromycin or chloramphenicol were recruited. The treatment failure rate did not differ significantly between patients receiving doxycycline and patients receiving azithromycin (6.0% vs 11.4%; P =0.109). However, a higher treatment failure rate was observed for chloramphenicol compared with doxycycline (14.6% vs 6.0%; P =0.004). No significant difference in time to defervescence was observed between patients receiving doxycycline, azithromycin or chloramphenicol. Further subgroup analysis revealed a higher risk of treatment failure for chloramphenicol compared with doxycycline in patients with acute kidney injury, pneumonia and shock; and a higher risk of treatment failure for azithromycin compared with doxycycline in patients with meningitis. Significant correlation was found between azithromycin resistance and meningitis (P =0.009), and between chloramphenicol resistance and acute respiratory distress syndrome (ARDS) (P <0.001) using Cramer's V correlation coefficient. Multi-variate Cox regression analysis revealed significant associations between time to defervescence and presence of ARDS, shock, myocarditis, meningitis and acute kidney injury. Azithromycin and doxycycline were found to have significant therapeutic effects in patients with severe ST. In contast, chloramphenicol was less efficacious for the treatment of these patients. [ABSTRACT FROM AUTHOR]

Beilong virus (BeiV), a member of the newly recognized genus Jeilongvirus of family Paramyxoviridae , has been reported with limited geographic and host scopes, only in Hongkong, China and from two rat species. Here, by next-generation sequencing (NGS) on dominant wild small animal species in 4 provinces in China, we obtained a complete sequence of BeiV strain from Rattus norvegicus in Guangdong, neighboring HongKong, China. We then made an expanded epidemiological investigation in 11 provinces to obtain the geographic distribution and genetic features of this virus. Altogether 7168 samples from 2005 animals (1903 rodents, 100 shrews, 2 mustelidaes) that belonged to 33 species of Cricetidae, Muridae, Sciuridae and Dipodidae family of Rodentia , 3 species of Soricidae family of Soricomorpha , 2 species of Mustelidae family of Carnivora were examined by RT-PCR and sequencing. A positive rate of 3.7% (266/7168) was obtained that was detected from 22 animal species, including 5 species of Cricetidae family, 12 species of Muridae family, 2 species of Sciuridae family and 3 species of Soricidae family. Phylogenetic analyses based on 154 partial Large gene sequences grouped the current BeiV into two lineages, that were related to their geographic regions and animal hosts. Our study showed the wide distribution of BeiV in common species of wild rodents and shrews in China, highlighting the necessity of epidemiological study in wider regions. • The largest sample size for the detection of BeiV. • A complete sequence of BeiV strain from Rattus. norvegicus in Guangdong. • The epidemiological distribution and genetic features of BeiV by Next-generation sequencing and RT-PCR. • BeiV of genetic diversity was correlated with its geographic origins and wild rodent hosts. [ABSTRACT FROM AUTHOR]

Background: Aedes albopictus is among the 100 most invasive species worldwide and poses a major risk to public health. Photoperiodic diapause provides a crucial ecological basis for the adaptation of this species to adverse environments. Ae. albopictus is the vital vector transmitting dengue virus in Guangzhou, but its diapause activities herein remain obscure. Methods: In the laboratory, yeast powder and food slurry were compared for a proper diapause determination method, and the critical photoperiod (CPP) was tested at illumination times of 11, 11.5, 12, 12.5, 13, and 13.5 h. A 4-parameter logistic (4PL) regression model was selected to estimate the CPP. In the field, the seasonal dynamics of the Ae. albopictus population, egg diapause, and hatching of overwintering eggs were investigated monthly, weekly, and daily, respectively. A distributed lag non-linear model (DLNM) was used to assess the associations of diapause with meteorological factors. Results: In the laboratory, both the wild population and the Foshan strain of Ae. albopictus were induced to diapause at an incidence greater than 80%, and no significant difference (P > 0.1) was observed between the two methods for identifying diapause. The CPP of this population was estimated to be 12.312 h of light. In the field, all of the indexes of the wild population were at the lowest levels from December to February, and the Route Index was the first to increase in March. Diapause incidence displayed pronounced seasonal dynamics. It was estimated that the day lengths of 12.111 h at week2016, 43 and 12.373 h at week2017, 41 contributed to diapause in 50% of the eggs. Day length was estimated to be the main meteorological factor related to diapause. Conclusions: Photoperiodic diapause of Ae. albopictus in Guangzhou of China was confirmed and comprehensively elucidated in both the laboratory and the field. Diapause eggs are the main form for overwintering and begin to hatch in large quantities in March in Guangzhou. Furthermore, this study also established an optimized investigation system and statistical models for the study of Ae. albopictus diapause. These findings will contribute to the prevention and control of Ae. albopictus and mosquito-borne diseases. [ABSTRACT FROM AUTHOR]