Officials in New Jersey and Pennsylvania have reported an outbreak of bird flu in those states. This comes just days after outbreaks at farms in Delaware led to the killing of thousands of chickens.

New Jersey health officials say evidence of the bird flu virus was found at four live chicken markets in northern New Jersey. And agriculture officials in Pennsylvania confirm a flock of poultry in the state has tested positive for the virus. The bird disease is the same strain as the type found at two Delaware farms since last week, resulting in the killing of 80,000 chickens.

However, officials stress that this strain is not dangerous to humans. They say it is not related to the avian influenza that has so far claimed 19 lives in Asia.

New Jersey officials say the discovery of bird flu in live chicken markets in the state is not unusual. They say they typically find avian disease at 40 percent of live poultry markets as part of regular testing.

Richard Lobb, who is a spokesman for the National Chicken Council, a trade association consisting of the United States poultry producers, says the findings are not surprising.

"To find a mild form of avian influenza, find evidence of that in these live bird markets is as surprising as finding the common cold in a kindergarten class. You're gonna find it from time to time," he said.

Mr. Lobb stresses the industry is taking all the necessary steps to prevent the disease from spreading further. Chicken producers are sealing up farms as much as possible by allowing only authorized personnel onto the farms. Other measures include washing down feed trucks before and after they visit farms, ensuring that farm workers wear protective clothing and wash down their boots in order to prevent transmission to other chickens. The virus can live in dirt and be transmitted unwittingly by human beings to other poultry.

Despite all the preventive measures, however, the discoveries in New Jersey and Pennsylvannia threaten to erode confidence and cause further damage the country's poultry industry.

Already, China, Japan and other Asian countries have banned U.S. poultry imports. Asia represents about 30 percent of the U.S. poultry industry's overall exports. Meanwhile, the biggest consumer of U.S. chicken, Russia, has banned imports from Delaware. With bird flu now present in more states, industry officials and farmers are worried that these bans might be widened.

Mr. Lobb says that would be a major blow to the poultry industry. "The total trade of the United States in poultry with other countries is worth over $2 bilion a year to the United States," he said. "And we certainly would not want to lose that or a large part of that. We understand that they are very sensitive about this particularly in Asia, but what they need to know is this is in fact the mild or so-called low pathogenic form of avian influenza and that the necessary steps are in fact being taken to control the outbreak."

Mr. Lobb says countries banning U.S. poultry products should do so on a selective case-by-case basis, as Russia has done, and not across the board.

Avian flu was first reported in Delaware last week.