New Jersey health officials stressed that the findings are not unusual for the state's live poultry markets and said the strain is not known to be harmful to humans.
Nancy Halpern, the state veterinarian, said the markets likely got the virus from one of the many farms and distributors who supply them. New Jersey has about 35 live chicken markets across the state.
"We believe the virus is coming to (the markets)," Halpern told The Star-Ledger of Newark in a story published Thursday. "They can be doing everything right and still have a market that tests positive."
Halpern said the state tested the markets in late January, as it typically does every winter, and results have been received for about half the sites. She would not identify the markets where the strain was found.
Markets found to be infected are instructed to sell off all birds, and then clean and sanitize all cages and equipment before reopening.
"Angela" at a poultry market in West New York, N.J. told WCBS-AM reporter Sean Adams nothing beats a live chicken for tasty home-cooked soup.
Now, however, she's switched to "meat, although I know it's that cow thing ... but I'd rather eat meat."
Officials said the strain found in New Jersey is the same one found at two farms in Delaware since last week. The strain is not related to the virulent variety of avian influenza that is blamed for the deaths of at least 19 people in Vietnam and Thailand.
Thailand confirmed three new human bird flu cases Thursday as health officials warned it could take two years to conquer Asia's outbreak.
Meanwhile, the World Health Organization said the latest tests show no sign of a killer hybrid virus that could easily pass between people.
Tests on a cluster of bird flu cases in a Vietnamese family showed there was no mixing of genes between the bird flu strain and human flu, according to WHO.
China said Thursday it was mobilizing 16,000 workers for anti-bird flu efforts in a province bordering Vietnam where China's first bird flu case of the season was confirmed in late January. Among their tasks is to try to pinpoint the source of the first infection.
Clifton Lacy, commissioner of the New Jersey Department of Health and Senior Services, said there was only a small chance that the weak strain could mutate into a stronger form that could harm humans.
"The key (to preventing problems) is stringent sanitary measures on farms and culling the flocks," he said.
Thai officials have said slaughters of more than 26 million chickens have brought the disease largely under control there, while Vietnam has said its outbreak is easing. In Pakistan, U.N. officials said the disease has been contained. But the U.N. Food and Agriculture Organization said it would take much longer to bring the region's outbreak under control.
In Delaware, the disease was found last week on a farm in Kent County operated by an independent grower who sold to a live bird market in New York City.
Then on Tuesday, Delaware agriculture officials announced that tests confirmed avian flu on a second farm, saying it was a surprise that creates a "serious situation" for the region's poultry industry.
Even before the announcement about the second flock, China on Tuesday joined Poland, Japan, Malaysia, Singapore and South Korea in banning U.S. poultry imports because of the previous discovery. Hong Kong had banned the import of live birds and poultry from Delaware only. Russia also temporarily banned Delaware imports.
Exports account for about 20 percent of the U.S. poultry industry.