Prevalence of Campylobacter and non-typhoidal Salmonella along broiler chicken production and distribution networks, Vietnam

Abstract

Abstract Campylobacterand non-typhoidalSalmonella(NTS) are among the most common foodborne pathogens found in chickens at any production stage and cause gastroenteritis in humans. This study aimed to estimate the prevalence ofCampylobacterspp. (C. coliandC. jejuni) and NTS in broiler production and distribution networks (PDN) using a Bayesian approach. A cross-sectional study was conducted in four provinces in northern Vietnam between March 2021 and March 2022. A total of 102 sites, including live bird markets, slaughter facilities (slaughterhouses and slaughter points), and their supplying farms, were randomly selected for sampling. Cecal and environmental samples were cultured for isolation ofCampylobacterand NTS, with serotypes of NTS determined by targeted analysis of whole genome sequences. Bayesian models were developed to estimate the prevalence ofCampylobacterat two levels (bird-level and site-level) and NTS at site-level. The selected best-fitted models indicated thatC. jejuniprevalence was primarily influenced by site type, whileC. coliwas affected by both province and site types. For NTS, only site type was included. The highest overall prevalence of infected broilers was estimated on farms forC. coli(26.2% [95% High Density Interval (HDI): 19.0-36.0%]) andC. jejuni(19.9% [95%HDI 13.0-27.0%]). Slaughter points (97.6% [95%HDI 63.3-99.9%]) and wholesale markets(91.7% [95%HDI 28.2-99.9%]) had the highest probability ofC. coliandC. jejunicontamination, respectively, but retail markets had the highest proportion of infected broilers at contaminated sites. NTS contamination was more frequent in markets and slaughter facilities (42.8% [95%HDI 30.8-57.1%]) than on farms (18.6% [95%HDI 9.5-30.1%]). Among 16 detected NTS serotypes,S. Infantis andS. Kentucky were the most common. These findings highlight the widespread contamination of broiler PDNs withCampylobacterand NTS in northern Vietnam, emphasizing the need for enhanced surveillance and control measures in PDNs to mitigate the risk of foodborne transmission. Author Summary Campylobacterspp. and non-typhoidalSalmonella(NTS) are enteric pathogens that are key global pathogens causing diarrheal diseases. TheCampylobacterspecies that are most frequently responsible for human diseases (campylobacteriosis) areCampylobacter jejuni(C. jejuni) andCampylobacter coli (C. coli). The severity of the salmonellosis depends on host factors and the serotype of NTS. Poultry and poultry products are recognized as major sources of NTS andCampylobacterinfections in humans. In Vietnam, these pathogens have been detected in the broiler production and distribution networks (PDN). Factors that may increase the risk of transmission of those pathogens include low biosecurity practices, inadequate waste management, and high farm density. In this work, we estimated the prevalence ofCampylobacterspp. (C. coliandC. jejuni) and NTS in PDN markets and slaughterhouses and farms supplying these facilities in four provinces in northern Vietnam. We estimated a high prevalence ofCampylobactercontamination in slaughter points and wholesale markets and higher NTS contamination in slaughter facilities and markets than in farms.S.Infantis was one of the most frequently identified serovars. However, it was not reported as being frequently detected in humans in Vietnam. Therefore, serovar may vary depending on the source and region of contamination. Our results help us look at levels of infection/contamination withCampylobacterand NTS in the broiler PDNs, thus informing stakeholders to prevent and control campylobacteriosis and salmonellosis.