Pennsylvania has become the third state in the United States hit by bird flu after viruses were found on farms and live bird markets in Delaware and New Jersey.

A poultry flock in Lancaster County, Pennsylvania, was infected by the H2N2 bird flu virus strain, Dennis Wolff, the state's agriculture secretary, has confirmed.

"This is not the strain currently in Asia or Delaware. We believe this indicates no threat to human health and a low threat to the poultry industry," Wolff said in a statement posted on the Pennsylvania Agriculture Department's web site late Friday.

The flock had no clinical signs to indicating illness with bird flu and no decrease in egg production has occurred. The farm in Mount Joy remains under quarantine, and all 16 poultry flocks in the surveillance zone are being tested.

In Delaware, where bird flu was discovered on two farms on Feb.6 and Feb. 9, no new cases have been reported so far. But officials said they will continue the search and are planning to expand testing for the virus.

More than 85,000 chickens have been killed in Delaware to contain the disease. Through Saturday, tests on 153 chicken houses at 61 farms within six miles (10 kilometers) of the two infected farms showed no further spread of the disease.

Agriculture officials said they will continue testing farms within the six-mile radius and begin testing outside the radius this week, local newspapers in Delaware reported on Monday.

Days after the outbreaks in Delaware, the same H7N2 virus was detected at four live chicken markets in New Jersey.

US officials stressed that both H2N2 and H7N2 are different from the H5N1 bird flu virus strain that is spreading in some Asian countries and post no harm to human health.

A dozen countries have banned imports of US poultry products after the virus first found in Delaware.

(Xinhua News Agency February 16, 2004)