Asymptomatic carrier birds may also transmit the virus. Birds can spread the virus to humans and other mammals, and humans are believed to be able to infect their pet birds. Some infected birds may be asymptomatic and recover, while others may die suddenly, without showing signs of illness. Very pathogenic strains may cause bleeding problems. The influenza virus is transmitted by direct contact with respiratory secretions and feces.
Ponds containing infective feces are important sources of infection for susceptible birds.
Although a pet bird could spread the virus to a human, the more important consideration is that a human, sick with the flu, can infect his or her pet bird. If a person has the flu, he should try to maintain minimal contact with his bird while ill and practice good hygiene. Birds showing signs of illness should be separated from other birds, examined by a veterinarian and treated symptomatically. Chlamydia and mycoplasma, as well as several other viruses, may cause signs similar to Avian Influenza. A definite diagnosis requires isolation and identification of the virus.