Feb 11, 2004 12:00 PM, from staff and wire reports

Another wave of avian influenza (bird flu) in Delaware forced state agriculture officials to order the slaughter of 72,000 additional chickens and suspend the sale of live poultry.

The latest outbreak of the H7 strain of this infectious disease was found just days after 12,000 chickens were destroyed to stop the spread of the virus from a southern Delaware farm.

Testing of all poultry farms in a two-mile radius of the first outbreak had been ordered to make sure the disease was isolated. The new cases were detected in a commercial flock about five miles away, Delaware officials said.

"This development is completely unexpected, given the precautions we took, the investigation we made, and the industry's expectations of this disease's behavior," said Delaware Agriculture Secretary Michael Scuse.

H7 is fatal to birds but does not harm humans. It is a different strain from the one that has killed at least 19 people in Asia and led to millions of fowl having to be destroyed.

The cases have caused seven nations to suspend at least some US poultry imports. Poultry exports from the United States total more than $1.7 billion annually.