獣医科学と技術

Concurrent Porcine Reproductive and Respiratory Syndrome Virus, Porcine Circovirus Type 2 and Pseudorabies Virus Infections Associated With 'High Fever Syndrome' in Swine of Northern China

Abstract

Xiaoling Wang, Feng Hu, Wencheng Lin, Zhao Wang, Kyoung-Jin Yoon and Shangjin Cui

Field and laboratory diagnostic investigation was conducted during recent outbreaks of "High Fever Syndrome (HFS)" in numerous large-sized swine farms in Xinjiang of China which obtained pigs from Jiangxi and Hunan Provinces where outbreaks of HFS coincided. The syndrome occurred in these provinces from April 2006 to June 2006 with a peak of index cases in late May 2006. The most common clinical symptoms of HFS in affected pigs were elevating body temperature and rubefaction. Overall morbidity and mortality ranged from 20 to 80%. In sow farms the abortion rate by HFS reached 65% and many weaned piglets had severe dyspnea. The incidence rate of the syndrome in finishing/marketing pigs (10-15 months of age) was up to 50%. In deceased pigs, organ failure was observed in the lungs, liver, spleen, intestines, and lymph nodes. Animals examined had serological evidence of prior exposure to pseudorabies virus (PRV). Furthermore, laboratory testing by a PCR assay on samples from clinically affected animals demonstrated that the majority of index animals were concurrently infected with PRRSV and porcine circovirus type 2, suggesting that epidemic outbreaks of HFS was attributed to infection by multiple viral agents. Many index cases appeared to be related to the application of multiple live virus vaccines in an uncontrolled manner, raising the necessity for implementation of rigid regulation for vaccination programs.