Prevalence of Streptococcus suis in pigs in China during 2000-2021: A systematic review and meta-analysis

Streptococcus suis (S. suis) is one of the most important pathogens affecting pig production worldwide. It can be also transmitted to human through the behaviors of eating undercooked pork or slaughtering sick pigs. A meta-analysis was conducted to estimate the prevalence across different geographical areas in China. Forty-three articles were included and distributed in 22 provinces of China. The prevalence of S. suis infection in pigs varied from 4.2% to 93.7%, with a summary estimate of 40.8% (95%CI, 32.9-48.6%). Six provinces, classified as frequent outbreaks in human cases, had a higher prevalence (52.7%, 95%CI: 43.7-61.6%) than other provinces (36.0%, 95%CI: 27.0-44.9%). Jiangsu province had the highest prevalence with 73.1% (95%CI: 70.42-75.68%), followed by Hunan (59.64%, 95%CI: 55.83-63.37%), Shanxi (55.56%, 95%CI: 47.05-63.83%), and Guangxi (50.55%, 95%CI: 49.45-51.64%). The prevalence has been decreasing gradually, from 47.6% (95%CI: 38.1-57.1%) before 2010, then dropped to 39.1% (95%CI: 25.5-52.8%) during 2011-2015, and reached the lowest in recent five years (2016-2020), with 34.3% (95%CI: 23.1-45.4%). The study findings showed that S. suis was presented in pig populations of most provinces of China, which indicated that effective control measures in pigs should be implemented. Our results also provided solid evidence for the early warning and prevention of human S. suis infection in China, which would mitigate the risk to humans.