High seroprevalence of Chlamydia infection in sows in Hunan province, subtropical China

Seroprevalence and Risk Factors of Chlamydia Infection in Pigs in Hunan Province, Southern China, 2017-2018

Background: Chlamydia is a Gram-negative obligate intracellular bacterium that is pathogenic for humans and a large variety of veterinary animal species. However, there is no continuous monitoring of 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: These findings elucidate a substantial prevalence of 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.

Seroprevalence of Chlamydia abortus and Brucella spp. and risk factors for Chlamydia abortus in pigs from China

Chlamydiosis and brucellosis induced abortions have resulted in significant economic losses in the global livestock industry. Although there have been numerous reports on these two diseases in ruminants in China, limited information is available regarding the prevalence of Chlamydia abortus (C. abortus) and Brucella spp. infection in pigs. This study aimed to investigate the prevalence of C. abortus and Brucella spp. infections in pig serum using serology and to identify potential risk factors. In total, 2816 serum samples were collected from 12 provinces in China. The presence of C. abortus antibodies was determined using an enzyme-linked immunosorbent assay (ELISA), while the presence of Brucella spp. antibodies was examined using the Rose Bengal Plate Test (RBPT) and the Standard Agglutination Test (SAT). The seroprevalences of C. abortus and Brucella spp. were 8.38 % (236/2816) and 0.11 % (3/2816), respectively. Geographical location, season, and age were found to be risk factors associated with C. abortus infection in pig herds in China (p<0.01), and the seropositive rate for C. abortus in sow herds was strongly associated with the occurrence of abortion (p<0.01). Overall, in China, pigs exhibit a higher seroprevalence of C. abortus, whereas the prevalence of Brucella is limited. This study represents the first comprehensive survey of C. abortus and Brucella spp. in pig herds in China that established potential risk factors and provided data for the prevention and control of intraspecies and interspecies transmission of C. abortus to humans.

Seroprevalence and Risk Factors of Chlamydia Infection in Cattle in Shanxi Province, North China

The information on Chlamydia infection in cattle is limited in Shanxi Province, north China. This study aimed to investigate the seroprevalence and risk factors of Chlamydia and Chlamydia abortus infection in cattle in Shanxi Province. In November 2020, a large-scale investigation of Chlamydia seroprevalence was conducted on 981 cattle serum samples collected from 40 cattle farms in 11 cities of Shanxi Province. The seroprevalence of Chlamydia and C. abortus was examined by indirect hemagglutination assay (IHA) and enzyme-linked immunosorbent assay (ELISA), respectively. The seroprevalence of Chlamydia and C. abortus was 52.29% (513/981) and 2.96% (29/981), respectively, in cattle in Shanxi Province. Location was identified as a risk factor for Chlamydia and C. abortus infection (p < 0.05). Under different management patterns, the seroprevalence of Chlamydia and C. abortus in large-scale animal farming companies was higher than that in household animal farms and animal farming cooperatives, and only the seroprevalence of Chlamydia was significantly different in different management patterns (p < 0.01). The results showed that there was higher seroprevalence of Chlamydia in cattle in Shanxi Province, while C. abortus was not the dominant species. This study provided baseline information on Chlamydia infection in cattle in Shanxi Province, which constitutes valuable data for monitoring livestock health and preventing potential zoonoses.

Prevalence of Chlamydia in Pigs in China from 1985 to 2020: A Systematic Review and Meta-Analysis

Chlamydia is a small gram-negative (G-) microorganism that can be dangerous to human and animals. In this study, we conducted a systematic review and meta-analysis of Chlamydia infection in swine in China. From PubMed, ScienceDirect, Chinese Web of knowledge (CNKI), VIP Chinese journal database, and Wanfang database, we collected a total of 72 publications reported in 1985-2020. The prevalence of Chlamydia was 22.48% in China. In the sampling year subgroup, the prevalence after 2011 was the highest (26.14%). In southern China, the prevalence was 30.97%. By contrast, the prevalence in northern China was only 10.79%. Also the difference was significant (p < 0.05). In the provincial level, Hubei had the highest rate of 36.23%. Boars had a higher prevalence (29.47%). The prevalence of Chlamydia detection in pigs with reproductive disorders (21.86%) was higher than that without reproductive disorders. Among the three age groups, finishing pigs (21.43%) had the highest prevalence. The prevalence in large-scale farmed pigs (28.58%) was the highest in the subgroup of feeding methods. The prevalence in farms was 24.29%, which was the highest in the survey areas. The prevalence in spring was the highest with 40.51%. Other methods had the highest prevalence (39.61%) than enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination assay. The prevalence of Chlamydia psittaci 18.41% was lower than the prevalence of Chlamydia abortus (41.35%). We also analyzed the impact of different climate factor subgroups (rainfall, temperature, and humidity) on the probability of pigs suffering from the disease. The results showed that Chlamydia was widespread in pigs in China. We suggest that we should strengthen the detection of Chlamydia in the semen of breeding pigs and pigs with reproductive disorders, and reasonably control the environment of large-scale pig farms, so as to reduce further infection of Chlamydia in pigs.

First Report of Chlamydia Seroprevalence in Slaughter Pigs in Shandong Province, Eastern China

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.

First Report of Chlamydia Seroprevalence in Farmed Wild Boars in China

Chlamydia is Gram-negative obligate bacterium, which can cause human diseases worldwide and has huge economic impact on animals. It is yet to know whether farmed wild boars are infected with Chlamydia in China. To assess risk factors of Chlamydia infection in farmed wild boars in China, from April 2015 to February 2016, a total of 837 serum samples of farmed wild boars were collected in Jilin province, northeastern China, and antibodies against Chlamydia were examined by the indirect hemagglutination assay. The investigation showed that antibodies to Chlamydia were detected in 332 (39.67%, 95% CI 33.36-42.98) of 837 serum samples of farmed wild boars, seroprevalence ranged from 33.71% to 44.42% among different regions and the differences were statistically significant by SPSS analysis (p = 0.0248). These results indicated that Chlamydia is highly prevalent in farmed wild boars in Jilin province, northeastern China, and may pose a potential risk for human health. To our knowledge, this is the first report of Chlamydia seroprevalence in farmed wild boars in China, which provided baseline data for preventing and controlling Chlamydia infection in wild boars in China.

Extended semen for artificial insemination in swine as a potential transmission mechanism for infectious Chlamydia suis

Although typically unnoticed, Chlamydia infections in swine have been shown to be both widespread and may impact production characteristics and reproductive performance in swine. Serum titers suggest Chlamydia infection within boar studs is common, and infected boars are known to shed chlamydia in their ejaculates. Although the transmission of viruses in chilled extended semen (ES) is well established, the inclusion of antibiotics in commercially available extender is generally believed to limit or preclude the transmission of infectious bacteria. The objective of this study was to evaluate the potential of ES used in artificial insemination to support transmission of the obligate intracellular bacteria Chlamydia suis (C suis) under standard industry conditions. First, the effect of C suis on sperm quality during storage was assessed by flow cytometry. Only concentrations above 5 × 10(5) viable C suis/mL caused significant spermicidal effects which only became evident after 7 days of storage at 17 °C. No significant effect on acrosome reaction was observed using any chlamydial concentration. Next, an in vitro infection model of swine testicular fibroblast cells was established and used to evaluate the effect of chilled storage on C suis viability under variable conditions. Storage in Androhep ES reduced viability by 34.4% at a multiplicity of infection of 1.25, an effect which increased to 53.3% when the multiplicity of infection decreased to 0.1. Interestingly, storage in semen extender alone (SE) or ES with additional antibiotics had no effect on bacterial viability. To rule out a secondary effect on extender resulting from metabolically active sperm, C suis was stored in fresh and expended SE and again no significant effect on bacterial viability was observed. Fluorescent microscopy of C suis in ES shows an association between bacteria and the remaining gel fraction after storage suggesting that the apparent reduction of bacterial viability in the presence of semen is due to adherence to gel fraction. Taken together, the results of this study suggest that C suis remains viable and infectious during chilled storage and is globally unaffected by antibiotics in extender. Thus, ES used in artificial insemination may act as a viable transmission mechanism for C suis in swine.

Seroprevalence and Risk Factors of Chlamydia Infection in Domestic Rabbits (Oryctolagus cuniculus) in China

Chlamydia spp. are obligate intracellular bacteria distributed all over the world, known to cause various forms of diseases in animals and humans. In the present study, a serological survey was conducted to detect the seroprevalence and risk factors associated with rabbit chlamydiosis in northeast China, including Liaoning province, Jilin province, Heilongjiang province, and Inner Mongolia Autonomous Region. Antibodies to Chlamydia were determined by indirect hemagglutination assay (IHA). The overall seroprevalence was estimated at 17.88% in total of 800 blood samples. The Chlamydia seroprevalence varied in domestic rabbits from different factors, and genders of domestic rabbits were considered as major risk factors associated with Chlamydia infection. Our study revealed a widespread and high prevalence of Chlamydia infection in domestic rabbits in northeast China, with higher exposure risk in female domestic rabbits. These findings suggested the potential importance of domestic rabbits in the transmission of zoonotic Chlamydia infection, and thus Chlamydia should be taken into consideration in diagnosing rabbit diseases. To our knowledge, there is no report of Chlamydia infection in domestic rabbits in China and the results extend the host range for Chlamydia, which has important implications for public health and the local economy.