Several premises in metropolitan Los Angeles were quarantined in early October after exotic Newcastle disease—one of the most infectious poultry diseases known—was detected in privately owned game fowl.
Federal, state, and local agriculture officials were scouring Los Angeles, San Bernardino, and Riverside counties to determine the scope of the outbreak and limit it to southern California. The fear is the virus could reach commercial poultry flocks in the area, resulting in mass slaughter and untold economic devastation.
Exotic Newcastle disease has not infected commercial poultry flocks in the United States since 1974.
Fortunately, in the early stages of the outbreak, the virus appeared to be confined to small backyard poultry operations that breed and exchange birds used in cockfighting, which is illegal in California.
As of Oct. 18, 50 premises had been quarantined—the virus was detected on 12 of them—and some 5,700 chickens slaughtered. None of the premises involved is adjacent to commercial poultry facilities.
The virus was detected after an owner reported the loss of around 200 game birds within five days. The Department of Agriculture's National Veterinary Services Laboratories confirmed the presence of exotic Newcastle virus in samples from the flock on Oct. 1.
The source of this outbreak isn't known, although it is speculated that infected birds were smuggled into California from Mexico. Birds carrying the virus have been confiscated at the border. Also, exotic Newcastle disease isn't unknown in California. It was detected in two birds as recently as several months ago.
"The bad news is we have (exotic Newcastle disease) at all," said USDA spokesman Larry Hawkins. "The good news is we do not have it in commercial poultry. None of our traces has implicated any commercial meat or shell egg operations."
There is a robust trade of these game birds through swap meets and shows in the Los Angeles basin. Until the virus is under control, however, the California Department of Food and Agriculture has suspended all poultry exhibitions at fairgrounds, and all bird owners have been asked to stop the movement and sales of backyard birds.
Exotic Newcastle disease is so virulent that many birds die without showing any clinical signs. All bird species are susceptible to the virus, which attacks the respiratory, nervous, and digestive systems. It is passed primarily through direct contact between healthy birds and the bodily discharges of infected birds.
High concentrations of the exotic Newcastle virus are in birds' discharges and can be spread easily on shoes, clothing, and other means. The virus is often spread by vaccination and beak trimming crews, manure haulers, and poultry farm employees. It can also survive for several weeks in a warm, humid environment on birds' feathers, manure, and other materials.
"This (outbreak) is not on the order of magnitude of 1971," Hawkins explained, referring to a massive outbreak in commercial poultry flocks in southern California that threatened the entire U.S. poultry and egg supply. Nearly 12 million birds were slaughtered at a cost of $56 million.
Since the terrorist attacks of Sept. 11, biosecurity at large-scale poultry operations in California has been increased, which has further protected flocks from disease, according to Hawkins.
The Office International des Epizooties, which monitors animal diseases worldwide, classifies exotic Newcastle disease as a list A disease, meaning the virus is highly transmissible and a serious threat to international animal trade. The USDA issued an emergency notice to its trading partners, as is required by OIE. But because commercial poultry operations are untouched by the outbreak, trade hasn't been affected.
California bird owners are being asked to report suspicious cases to a veterinarian or the state Department of Food and Agriculture.