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Although some Chinese pig farms successfully eradicated Pseudorabies (PRV) during last years and most farms actively vaccinate against PRV, the disease is still endemic in swine in the country. This study aimed to add new epidemiological data on PR prevalence in China through a serological survey in pig rearing Chinese provinces using diagnostic submissions during 2012.
The survey involved 15 different Chinese provinces. A total of 7,090 serum samples were collected from breeders in 210 different farms during 2012. Sampling was designed according to the ratio of 5% of breeders, including boars, gilts and sows at different parities housed in commercial farms (250-6000 sows). A farm was considered PR positive when at least one sample was gE positive (gE+).
These results showed no major changes on PR prevalence in China comparing to previous epidemiological studies. Therefore, PR can still be considered as an endemic swine disease in the country, affecting about 40-50% of the commercial farms. Although the percentage of positive farms showed a downward trend from 2008 to 2011 (from 56% to 42%), it showed a slight upward trend in 2012 (44%). This could be related to the fact that during last year they reported the PR-reinfection of some farms in different Chinese provinces (own data). This fact emphasizes the necessity of establishing intensive vaccination programs and selection of PR-negative breeders replacement even in gE- farms due to the high risk or reinfection since PR is and endemic disease in China Moreover, seroprevalence in breeders showed an upward trend as well compared to 2011 (15.8% vs. 20.0%), especially in positive farms (35.0% vs. 40.6), since farms with lowest seroprevalence turned into negative farms, meanwhile farms with higher seroprevalence failed to decrease it, probably because they did not establish any sort of PR-control program yet.
Torrents D., Zeng R., Li C. Survey of Pseudorabies sero-prevalence in breeders in China during 2012. The 6th Asian Pig Veterinary Society Congress. 2013.