Seroprevalence of pullorum disease in chicken across mainland China from 1982 to 2020: A systematic review and meta-analysis.

Pullorum disease (PD), caused by the bacterium Salmonella pullorum, severely threatens the health of chickens worldwide, especially in China, and generating concerns for public health safety. Greater awareness of the seroprevalence may facilitate the prevention and control of this disease. We conducted systematic review and meta-analysis on the seroprevalence of PD in chicken flocks across mainland China. The results show that the overall pooled estimates of PD seroprevalence in chicken flocks was 18.2%. Furthermore, during 38-year period the seroprevalence of PD was markedly high in all seven regions, being at least 14.9% in central China. Our results suggest PD was highly prevalent in autumn, followed by winter. Chickens older than 120 days (22.6%, CI: 14.5%-31.9%) had a significantly higher positive rate of PD than those <120 days in age (9.4%, CI: 3.7%-17.4%). Additionally, the rearing mode used is a risk factor associated with the seroprevalence of PD, it being considerably lower for caged chickens (13.7%, CI: 7.1%-22.0%) than free-range chickens (30.4%, CI: 17.3-45.4%). Our findings demonstrate that PD still poses a major threat to poultry industries in mainland China, and therefore comprehensive and stringent strategies are needed to prevent and control this disease.