Abstract: To understand the prevalence of Streptococcussuis in swine herds in China, this study conducted a detection of Streptococcussuis in 1 756 samples from 18 provinces including Jiangxi, Fujian and Hainan, collected between January to June 2025. Serotype identification was performed on positive samples. The results showed that: ⑴ the overall positive rate was 31.89% (560/1 756), with significant differences in monthly detection rates (P＜0.05), with the highest rate in February(42.11%, 56/133) and the lowest in March (17.82%, 62/348); ⑵there was a significant correlation with age, with detection rates showing a trend of "decreasing first and then increasing" with age, with the lowest rate in pigs aged 41 to 60 days (13.44%, 25/186) and the highest rate in pigs aged 121 to 140 days (71.43%, 20/28). Among pigs aged under 40 days, suckling piglets and early nursery pigs were predominantly infected with serotype 29 (28.7%, 27/94) and serotype 9 (17.02%, 16/94); ⑶there was uneven regional distribution, with detection rates significantly higher in the south than in the north. Jiangxi (51.11%, 46/90), Fujian (50.00%, 17/34), and Hainan (47.06%, 16/34) ranked the top three, while no detection was found in provinces such as Liaoning, Shaanxi and Hubei; ⑷there were significant differences in sample types and serotypes, with different detection rates and predominant serotypes in blood, tissue and other samples; ⑸mixed infections were prominent, with 42.4% (79/186) of samples detecting two or more serotypes. In summary, the infection of Streptococcus suis in swine herds in China presents complex characteristics of "high positive rate, significant regional, age, and sample type differences, and widespread mixed infections", necessitating urgent attention to prevention and control.

Key words: swine, Streptococcus suis, epidemiological, survey analysis, serotype