In a sweeping study that spans nearly three years and 29 provinces, researchers have uncovered alarming trends in the spread of Riemerella anatipestifer, a bacterium traditionally known for devastating waterfowl populations but increasingly threatening China’s chicken farms. The research, led by Can Zhang from the College of Veterinary Science at Qingdao Agricultural University, offers a stark warning to the poultry industry and a roadmap for combating this growing menace.
The study, published in the journal Poultry Science (translated as 家禽科学), collected and analyzed 27,136 samples from septicemic chickens and dead embryos between 2021 and 2024. The findings reveal a bacterium on the move, both geographically and in terms of its preferred hosts. “We observed a rapid expansion from 10 to 19 provinces, with isolation rates skyrocketing from 1.03% to 4.56%,” Zhang explains. The data shows that R. anatipestifer is not only spreading but also adapting, with younger chickens now bearing the brunt of the infections.
The shift in infection rates is particularly concerning for broiler farms. Among 3–6-week-old white-feathered broilers, infection rates surged from 0.99% to 13.24%, with leg lesions being the primary symptom. Meanwhile, layers aged 50-100 days showed a 2.16% rate of salpingitis, an inflammation of the oviduct. The bacterium’s tissue-specific colonization preferences were also highlighted, with high loads found in oviducts (21.68%) and hocks (10.89%).
One of the most troubling discoveries was the potential for vertical transmission. While R. anatipestifer was detected in 20.18% of early “jelly-like embryos,” it was not found in semen or ovarian follicles. This suggests a possible route of transmission from hen to offspring, complicating control efforts.
Serotyping revealed a dominance of type 1 (70.82%) and type 10 (15.86%) strains, with 2.83% remaining untypable. However, the real cause for concern lies in the bacterium’s resistance to commonly used antibiotics. Enrofloxacin, polymyxin, and amikacin showed alarmingly high resistance rates of 91.54%, 88.22%, and 86.10%, respectively.
The implications for the poultry industry are significant. As Zhang notes, “This is the first large-scale survey of R. anatipestifer in chickens, and our findings highlight its cross-species adaptation and increasing prevalence in young broilers.” The study not only contributes to the understanding of the epidemiology of R. anatipestifer in chickens but also provides crucial data for evidence-based control strategies.
For the poultry sector, the research underscores the need for vigilance and innovation in disease management. The rapid spread and high resistance rates demand a proactive approach, potentially driving advancements in biosecurity measures, vaccine development, and alternative treatment methods. As the industry grapples with these challenges, the insights from this study will be instrumental in shaping future strategies to safeguard poultry health and productivity.
In the broader context, this research serves as a reminder of the dynamic nature of infectious diseases and the constant need for surveillance and adaptation. As Can Zhang and his team have shown, understanding the epidemiology of emerging threats is the first step in mitigating their impact. With the data now available, the poultry industry can take informed steps to protect its flocks and ensure the sustainability of chicken farming in China and beyond.