Pig Disease in China Worries the World

One area that animal disease experts say they want clarified is the numbers. According to the most recent Chinese government estimates, 68,000 pigs died from blue ear disease, 175,000 were slaughtered and an additional 1.5 million were vaccinated in the first eight months of this year. But in a typical year, China loses some 25 million pigs to disease.

So if the official numbers were true, China would be having better-than-normal year for pigs, not a worse one.

"The statistics are not accurate. There's some inconsistency. Some local officials have provided their most conservative estimates in order to protect their good reputations," said Chen Qingming, secretary general of the pig breeding division of China's Association of Animal and Veterinary Sciences.

There are also concerns that the disease that is killing so many pigs may not even be blue ear disease after all or that a type of blue ear virus -- known as porcine reproductive and respiratory syndrome -- has mutated into a much more lethal form.

In the PLoS ONE paper, Chinese scientists describe a vicious pathogen that can decimate an entire pig population in three to five days. They say autopsies showed severe damage to multiple organs, including lungs, spleen and kidneys.

"The last two years have seen a radical evolvement of the virus. It has become highly killing, and it is combining with many other diseases," said Zhu Guoqiang, a professor of veterinary medicine at Yangzhou University.

"Given the mortality rates that we are seeing, it is something more than the virus -- either a mutation from an environmental situation, bacterial infections or even a second virus. . . . We have not gotten to the bottom of it," said the FAO's Lubroth.

Though there's no evidence that the virus poses a threat to humans, there are signs that diseased pigs already have entered the food supply either directly because farmers may be trying to pass off diseased pigs as healthy ones, or indirectly because they have been thrown into water used for fishing or for drinking.

"So far, there is no indication that this disease is going to affect human beings," Huang said. "It still should be considered an animal disease, although we can't make this argument 100 percent. That would be a mistake. Many diseases jumped from animals to humans."

In Vietnam, where 33,000 pigs were infected in June and July, according to the government, local media reported that two people died in northern Vietnam after eating infected pork.

Reached by phone in Hanoi last week, Hoang Van Nam, deputy director of Vietnam's animal health department, said that government investigators determined that while the pair did eat meat from sick pigs, they were not infected by blue ear disease but by Streptococcus suis, which can go from pigs to humans.