*China pig deaths caused by a new and highly pathogenic strain of blue
ear disease*

26 Jun 2007 08:56:43 GMT
Source: Reuters

By Tan Ee Lyn

HONG KONG, June 26 (Reuters) - A pig disease that swept through 10
provinces in China decimating the swine population and ramping up pork
prices was caused by a new and highly pathogenic strain of blue ear
disease, Chinese scientists said.

The epidemic spread to almost half of China in 2006 and was atypical of
previous outbreaks of the disease, the scientists said in a paper
published in the June issue of the Public Library of Science.

It affected more than 2 million pigs and killed 400,000 of them, they said.

However, China's top vet said earlier this month that a variation of the
Porcine Reproductive and Respiratory Syndrome (PRRS), or blue ear
disease, killed a million pigs in 2006 and more than 18,000 hogs in the
first five months of 2007.

The scientists revealed details of the new virus strain and said it may
be responsible for several new and unusually severe symptoms, even in
adult pigs.

(The article is freely available on
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=188528 4.)
Although a serious swine disease, PRRS in the past mainly caused
reproductive failure in pregnant sows or respiratory tract distress in
suckling pigs. Usually, it was the piglets that succumbed.

NEW STRAIN, NEW SYMPTOMS

But this new virus strain spread very quickly, resulting in
"unparalleled large-scale outbreaks" and caused high fever (40-42
degrees Celsius), shivering and a reddish rash brought on by congestion
in the blood capillaries, the scientists wrote.

Autopsies confirmed that multiple organs, including the brain, spleen,
lymph nodes, liver, heart, tonsil and kidney were infected, they said.

"To our surprise, many grown pigs also died during this epidemic period,
which is unlike the case for typical PRRS virus infection," the
scientists said.

Using genetic analyses, the scientists discovered changes in the
molecular structure of the virus which made it unusually aggressive.

"Environmental factors such as temperature and relative humidity in the
summer and secondary bacterial infections may contribute to the
generation of highly virulent PRRS," they said.

China has stepped up its fight against the virus, which has caused
enormous economic losses and contributed to soaring domestic pork
prices, even feeding into national inflation levels. It launched a
vaccination campaign last week.

The PRRS virus was first recognised in the United States in the
mid-1980s and the disease costs the U.S. swine industry some US$600
million each year.