What is it?
Avian influenza (AI) viruses can infect chickens, turkeys, pheasants, quail, ducks, geese and guinea fowl, as well as a wide variety of other birds. Migratory waterfowl have proved to be a natural reservoir for the less infectious strains of the disease known as low pathogenicity avian influenza. AI viruses can be classified into low pathogenicity (LPAI) and high pathogenicity (HPAI) based on the severity of the illness they cause. HPAI is an extremely infectious and fatal form of the disease that, once established, can spread rapidly from flock to flock. However, some LPAI virus strains are capable of mutating under field conditions into HPAI viruses.
Birds affected with all forms of AI may show one or more of the following: Sudden death without clinical signs; Lack of energy and appetite; Decreased egg production; Soft-shelled or misshapen eggs; Swelling of the head, eyelids, comb, wattles, and hocks; Purple discoloration of the wattles, combs, and legs; Nasal discharge; Coughing, sneezing; Lack of coordination; and Diarrhea. Note: Many birds with LPAI may not show any signs of disease.
Exposure of poultry to migratory waterfowl and the international movement of poultry, poultry equipment, and people pose risks for introducing AI into U.S. poultry. Once introduced, the disease can be spread from bird to bird by direct contact. AI viruses can also be spread by manure, equipment, vehicles, egg flats, crates, and people whose clothing or shoes have come in contact with the virus. AI viruses can remain viable at moderate temperatures for long periods in the environment and can survive indefinitely in frozen material.
Highly pathogenic avian influenza (HPAI) H5 infections have been reported in U.S. domestic poultry (backyard and commercial flocks), captive wild birds, and wild birds. HPAI H5 detections began in December 2014 and have continued to date in 2015.
No human infections with these viruses have been detected at this time; however, similar viruses have infected people in other countries and caused serious illness and death in some cases. Human infections with other avian influenza viruses have occurred after close and prolonged contact with infected birds or the excretions/secretions of infected birds (e.g., droppings, oral fluids).
While the health risk posed to the general public by these domestic HPAI outbreaks is low at this time, it is possible that human infections with these viruses may occur.