WASHINGTON (Reuters) - A strain of bird flu which is devastating to commercial chicken flocks but not harmful to humans has spread into Pennsylvania and more cases may be found in Delaware, agriculture officials in both states said on Thursday.
The disease was also confirmed in four small poultry markets in northeastern New Jersey, a state which has had the disease for a dozen years and does not have any large, commercial flocks, according to its state officials.
The H7 avian influenza in the three states is a different strain than the H5N1 virus that has devastated flocks in 10 nations in Asia. Some 19 people have died in that outbreak.
Because avian influenza is spread easily, authorities often quarantine infected farms and destroy their birds. A dozen nations have banned all or some U.S. poultry shipments since the first infected flock was found last week in Delaware.
Farmers fear the disease because it can rapidly spread throughout a flock, cutting egg production and producing misshapen or soft-shelled eggs. Bird flu is spread through the birds' feces or mouth secretions and can infect turkeys, pheasants, quail, ducks, geese, and migratory birds.
The disease is so contagious that Delaware officials have asked farmers to post "keep out" signs on their property, to stop taking tractors and farm equipment to auction and to have essential visitors wear disposable biosecurity clothing.