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Vol 19 No. 1
February 2008

Pig Disease in China Worries the World, Lack of Data Impedes Research

FOSHAN, China -- At first, it was just some of the piglets. The mother gave birth to 13, all of them stillborn. Within a few weeks, however, she and other adult pigs in neighboring stalls became feverish and died. By the end of the summer, all but a handful of the village’s 300 pigs had succumbed to the mysterious disease.

“It was quick, very quick. Before we knew something was wrong, they were all dead,” said Lo Jinyuan, a 55-year-old pig farmer in the village of Shandi. Moving rapidly from one farm to the next, the virus has been devastating pig communities throughout China for more than a year, wiping out entire herds, driving pork prices up nearly 87 percent in a year and helping push the country’s inflation rate to its highest levels since 1996.

The Chinese government has admitted that the swine deaths amount to an epidemic but contends that the situation is under control.

China says it is moving swiftly to stop the infections by quarantining and slaughtering the affected pigs. It says its researchers have developed an effective vaccine in record time for the likely cause -- blue ear pig disease, a reproductive and respiratory illness that is highly fatal in pigs but that so far does not seem to pose danger to humans. And it maintains that it has been “open and transparent” all along.

Some experts, both inside and outside China, are skeptical, citing the government’s handling of the avian flu outbreak in 2004 and SARS in 2002 and 2003. While China’s central government has made numerous improvements since then in how it deals with infectious disease control and informs the public, it has once again been slow to share scientific data and tissue samples with other countries.

As a result, there is worry that while China is lagging, the virus is quickly turning into a global problem. China does not export pork to the United States, but the virus has already been found in pigs in China’s southern neighbors, Vietnam and Burma.

“We are concerned that with international traffic this particular virus could enter other continents -- Europe or Africa or the Americas,” said Juan Lubroth, head of infectious diseases for the United Nations Food and Agriculture Organization, based in Rome. “We have no firsthand or independent evaluation of the virus or vaccine. It’s all been conducted by the Chinese in China.”

While China’s previous reluctance to share information may have been the legacy of years of secrecy, its reasons for withholding information this time may be about something else: business interests.

For China, one the largest exporters of pork and pork products in the world and the target of recent criticism for the safety of its food and other exports, “there are economic-commercial incentives to cover up,” said Yanzhong Huang, editor of the Journal of Global Health Governance and an assistant professor at Seton Hall University.

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 only do so when “intellectual property issues” were resolved.

“We discussed this issue at length. . . . We decided to come up with an agreement between the Chinese government and any laboratory that receives the virus, a clear agreement of the two parties that it is just to be used for scientific purposes,” Martin said.

Among the possible conditions for the sample sharing that are being discussed: that patents and royalties from the development of vaccines and treatments remain the property of China. “There has been a feeling that in the past, some Chinese scientists have not been given recognition for their contributions,” Lubroth said. The FAO said Chinese officials agreed to meet again this month to set up a small working group to discuss the details of the intellectual property agreement. The group would also talk about the possibility of convening a regional forum to discuss scientific issues related to the epidemic.

Officials at the Ministry of Agriculture declined to answer questions by phone about the pig deaths and did not respond to questions faxed to them. The tissue samples that China has obtained are the key to any scientific research on what’s killing the pigs in China. Without them, it’s impossible to verify the type of illness, much less develop a cure for it. As with all viruses, the more the blue ear pig disease spreads, the more money there is to be made in a vaccine.

Mao Changqing, an analyst with CITIC Securities in Beijing, estimates that the blue ear vaccine market in China’s domestic market alone is worth roughly $105 million this year and -- assuming the virus continues to kill -- up to $265 million next year. It is against this backdrop that worries are mounting that what seemed to be an ordinary outbreak of swine disease here in Guangdong province on the country’s southern coast -- the same place where some of the earliest cases of avian flu were reported -- is mutating and spreading.

At least 26 of China’s 33 provinces and regions have announced they found diseased pigs within their borders. The FAO said in interviews last week that it has confirmed that the disease is moving to the west, where some breeders from the southern areas had taken their pigs to keep them safe in the early months of the disease. The FAO said one of the latest outbreaks occurred in July near Chongqing, an industrial city in southwestern China where many U.S. companies operate. Chinese officials have been tracking a mysterious illness in pigs since summer 2006, when more than 2 million pigs fell ill and 400,000 of them died. But it wasn’t until this year that China was able to confirm that blue ear pig disease was the cause. Chinese officials said that they informed the public as soon as they knew.

Since then, the government has made regular public announcements detailing the number of ill pigs and the progress of the disease through the country. This stands in sharp contrast to how China dealt with SARS, which originated in animals but jumped to humans and spread rapidly around the world before China admitted that the virus may have originated within its borders. The most detailed information about the disease appeared in a paper published in a new online scientific journal called PLoS ONE, run by the nonprofit Public Library of Science in San Francisco. Written by a team of animal researchers from China’s top academies, the paper traces the epidemiological origin of the virus, provides pictures of the pathogen under an electron microscope and offers its genetic sequence.

But the public paper released by the Chinese scientists has had only a cursory peer review -- by editors of the paper, whose goal is to get information up faster and leave it online for public peer review -- and leaves many questions unanswered.

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.

At the end of August, China launched an aggressive public education campaign about the pig disease, printing 600,000 handbooks about prevention and control of blue ear disease and dispatching 251 experts to disease-stricken areas. On Aug. 30, it passed laws that would provide for harsher punishments for animal owners who do not comply with vaccination policies and who did not report possible outbreaks.

In the countryside around Foshan, the brick pig stalls that line the roads are empty, and so now are the houses. Many of the farmers who used to raise pigs have left to try to find jobs in factories.

Those who remain rarely leave their homes for fear of carrying the disease and inadvertently transmitting it to their pigs. Many said they did not know the name of the disease that has affected the pigs and that much of what they had heard may be superstition.

Since May, Xie Hanquan, 53, has barricaded himself and his family inside his pig farm. His 200 pigs are healthy, but he’s worried that his neighbors may bring the disease to his farm. When he has to go out to get food and supplies, he makes sure to change his clothes and douse his shoes and body with disinfectant alcohol before opening the metal fence to his home. “Everyone is afraid now,” Xie said.

Two pigs belonging to Lo, the farmer from Shandi, gave birth to stillborn babies in June.

Shortly afterward, the two pigs died. Lo said he threw the bodies in a nearby river. He said it was common practice.