Occurrence of among pigs with respiratory disease in China between 2011 and 2015.

BACKGROUND

Prior to the 1990s, capsular serogroup A was the most prevalent in China, followed by serogroups B and D. Thirty years later, serogroup D became the most prevalent, followed by serogroups A and B. However, the capsular serogroups currently circulating in China remain unclear. Therefore, the aim of the present study was to provide an update on serogroups isolated from diagnostic samples collected from clinically diseased pigs in Central and Eastern China from 2011 to 2015.

RESULTS

Between February 2011 and October 2015, 296 isolates of were collected from 3212 pigs with clinical respiratory disease in 12 provinces of China (isolation rate of 9.2%). Of the 296 collected isolates, 146 (49.3%) were capsular type A, 141 (47.6%) were capsular type D, and one was capsular type B. (94/193; 48.7%), (76/193; 39.3%), (53/193; 27.5%), and (26/193; 13.5%) were frequently isolated together with A total of 14 toxigenic strains co-isolated with other pathogens from 32 cases of atrophic rhinitis were classified into serogroup D. The virulence of capsular type A isolates was higher than that of capsular type D isolates based on LD studies in mice.

CONCLUSIONS

Over the past 5 years, capsular type A was the most frequently isolated from diagnostic submissions in Central and Eastern China, followed by serogroups D and B.