Chinese Swine Disease Update ? Firsthand Accounts

September 19, 2007 — 

The Chinese government has now conceded that the on-going outbreak of disease in Chinese pig herds has reached epidemic proportions, but they still contend it is under control. We had a chance to visit with some Chinese attendees at the recent Leman Swine Conference and got their take on the outbreak.

Independent information on the disease outbreak continues to be sketchy and official government reports often conflict with those of locals and the global media. Chinese government scientists have reportedly isolated a PRRS variant to which they have developed what they report to be an effective vaccine. Their findings, included in a paper entitled Emergence of Fatal PRRSV Variants: Unparalleled Outbreaks of Atypical PRRS in China and Molecular Dissection of the Unique Hallmark published in the open source journal PLoS One, have been met with skepticism from some PRRS researchers.

Independent analysis of the disease agent and vaccine efficacy has not been forthcoming. Vincent Martin, an animal-health officer for the FAO in Beijing, said Chinese officials he met with last week said they were not opposed to sending samples to overseas laboratories but would do so only when "intellectual-property issues" were resolved. Particularly at issue is the payment of royalties and patents for the development of vaccines or treatments.

During the recent Leman Swine Conference, attendees from China's pork industry were willing to discuss what they were experiencing. The disease syndrome they describe started in 2006 in Jiangxi Province and has since spread across the country. The disease initially started with high fevers and elevated mortality in grow/finish pigs. More recently, the clinical signs observed include high fevers, high mortality, CNS signs, swollen joints and eyelids, and late-term abortions. Researchers announced the finding of a new PRRS variant in November, 2006 and developed PCR primers in June, 2007.

Of 1500 "sources" sampled, 30% were PCR positive to the new PRRS variant. In addition, Streptococcus suis was isolated from 1/3 of the cases and Haemophilus parasuis from another third. The samples are negative for PRV. The Chinese attendees indicated that Classical Swine Fever (CSF) is endemic in China's pig herd and that producers routinely vaccinate for CSF as well as Foot and Mouth Disease (FMD) and Pseudorabies (PRV). Some herds were vaccinating against PRRS prior to this most recent outbreak using a Chinese vaccine. This did not appear to prevent infection with the latest pathogen.

According to the group, live hog prices have doubled since April, 2007 and the government began importing large amounts of pork in August, 2007. Recently, they report having experienced fewer outbreaks. Although China does not export pigs or pork products to the U.S. it is one of the largest exporters of pigs and pork products in the world. USDA officials and U.S. pork producers have expressed concern that the disease could find its way here. Actual mortality figures in China vary widely but most reports indicate that the disease has killed in excess of 400,000 pigs and perhaps as many as 1 million. Reportedly, it is not uncommon for pig farmers to dispose of dead pigs by throwing them into local rivers and streams. It appears that the disease may have spread into Vietnam and Myanmar. The disease reportedly infected 33,000 pigs in Vietnam.