A viral poultry disease sickened and killed birds in at least 15 Southern California backyard flocks in May and June.
Virulent Newcastle disease is deadly to all bird species and can kill entire flocks, according to the U.S. Department of Agriculture.
The first known infections occurred in chickens in Los Angeles County, as confirmed May 17 by the USDA Animal and Plant Health Inspection Service. Agency officials identified more infections, all in neighboring San Bernardino County, in a collection of chickens, doves, and psittacines on May 24 and in 13 chicken flocks during May 26-June 14.
The number of birds killed by the virus was not immediately available. In the first 10 flocks with infections, about 1,800 birds were euthanized through AVMA-approved methods, according to APHIS.
Virulent Newcastle disease affects respiratory, nervous, and digestive systems, sometimes felling birds without any signs of disease.
APHIS spokeswoman Joelle Hayden provided a statement saying that the agency is encouraging bird owners and their veterinarians to watch for and report illnesses or increased deaths. Signs can include sneezing, gasping, nasal discharge, coughing, open-beak breathing, green and watery diarrhea, lethargy, tremors, drooping wings, twisting of the head and neck, stiffness, subcutaneous hemorrhaging, and swelling around the eyes and neck.
People who work with sick birds can develop conjunctivitis, APHIS information states.
The virus is transmitted through bodily fluids, and it can be transported on shoes and clothing, APHIS information states. It can survive several weeks on feathers and in manure if the weather is warm and humid, and indefinitely in frozen material. It can kill even vaccinated poultry.
State and federal investigators were looking for links between the infections as of mid-June.
Veterinarians who see birds with signs of virulent Newcastle disease can call APHIS at 866-536-7593 or the California Department of Food and Agriculture at 866-922-2473. APHIS will send veterinarians trained to investigate and collect samples.