August 30, 2004

WHO Urges Countries Hit By Bird Flu To Boost Pig Monitoring

Countries hit by bird flu must boost their monitoring of pigs after Chinese scientists discovered that the animals have been carrying a deadly strain of the virus, a senior World Health Organization official said Friday.
 
Klaus Stohr, head of WHO's global influenza program, also warned that fighting bird flu has become tougher because it has a solid hold in affected countries.
 
China said last week that it had found two strains of avian flu in pigs, including the H5N1 strain of the disease that killed 27 people earlier this year in Vietnam and Thailand.
 
Pigs, which are genetically similar to people, often carry the human influenza virus. Experts worry that pigs infected with both bird flu and its human equivalent could act as a "mixing bowl," resulting in a more dangerous, mutant virus that might spread to people more easily - and then from person to person.
 
They fear that could fuel a devastating flu outbreak, vastly exceeding the current annual death toll from human influenza, which kills 500,000 to 1 million people around the world each year.
 
"What's important now is that not only China, but all affected countries step up surveillance in pigs," Stohr told reporters.
 
A total of 100 million ducks, chickens and other birds in Asia have died of the illness or been slaughtered in an attempt to contain the outbreak this year.
 
Malaysia discovered its first case last week and has killed hundreds of birds.
 
"Looking at the scope of the outbreak in Asia, it's almost inevitable that a few pigs are being infected," Stohr said.

Pigs can pick up the virus from sniffing the ground, although this doesn't mean they have the disease. In an earlier outbreak that swept through Asia, nasal swabs from pigs in Vietnam tested positive for bird flu, but blood tests later showed they were not infected.
 
Stohr noted that regular studies in Hong Kong since 1999 using 200 swabs taken monthly from pigs imported from China showed no sign of the H5N1 virus.
 
"They key question, which we cannot answer at the current time, is whether this H5N1 virus becomes established in pigs. That would change the whole ballgame," said Stohr.
 
"The other news, which isn't really comforting, ... is that this H5N1 virus has gained increased power to sicken birds as well as mice" in laboratory tests, showing that it can hit mammals just as hard, he added.
 
Experts also are concerned because bird flu, which was often spread by imports of live birds in the past, "has got a foothold on the ground," hampering the battle against it, said Stohr.
 
"The disease is maintaining itself. You don't need an external input into a country to keep the disease alive," he said.
 
"We said that if the disease became endemic we would not be talking about days or weeks or months" to lessen the risk of its leaping the species barrier, he added. "We're thinking in terms of years."