Worry Grows Over Spread of Bird Flu

BANGKOK, Thailand —  The bird flu outbreak in Asia has spread to humans in Thailand and appeared in Cambodia, officials said Friday, as the European Union banned imports of Thai chicken.

After days of declaring the country free of the virus that has killed six people in Vietnam, the Thai government said two boys, ages 6 and 7 and from different provinces west of Bangkok, were “critical but stable” with the disease. Three more people were being tested, and the government issued an urgent warning to people in contact with poultry.

The World Health Organization said the near-simultaneous outbreaks in Japan, South Korea, Vietnam and now Thailand and Cambodia were “historically unprecedented,” and it expressed worry that a new, virulent strain of influenza could sweep the world.

That could happen, it said, if someone contracted human and bird flu at the same time, allowing the viruses to exchange genes and form a new strain that could spread rapidly.

So far, there is no evidence that has happened. All of the known cases have occurred through contact with chickens.

Thai Prime Minister Thaksin Shinawatra today denied accusations that his government covered up the outbreak.

“We were trying to do and say little, and whatever wasn’t yet official, we didn’t say,” he said. “That ... doesn’t mean we weren’t working.”

Thai farmers have been saying for more than a week that their chickens were dying of bird flu. But until Friday, officials had said the chickens were suffering from fowl cholera, which they said posed no danger to people.