Pigeons and influenza viruses
BY: Carol Cardona, Extension poultry virologist
Taken from University Minnesota Extension
- Pigeons are quite resistant to infection of avian influenza virus (AIV).
- Pigeons can be potential hosts of AIV, as shown by research.
- There are very few documented, natural infections of AIV in pigeons. AIV may adapt to pigeons and cause disease.
- If a pigeon is infected with H5 sublineage viruses, clinical signs present mostly as neurologic and greenish diarrhea.
What does the research show?
In a few studies, researchers introduced pigeons to the avian influenza virus (AIV). These studies show that pigeons are quite resistant to infection.
AIV from chickens and emus
Panigrahy et al. 1996 introduced pigeons to AIV from chickens and emus. They gave 8 to 32 month-old pigeons AIV through an intravenous (IV) or nasal passage. Virus antibody titers were not present after 21 days. Choanal or cloacal swabs and internal organs were free of the virus.
Pigeons given the virus did not spread it to chickens in direct contact.
Researchers used both low and high pathogenicity viruses in this study.
H5N1 Hong Kong virus
Perkins et al. 2002 gave 4-week-old pigeons (some already infected with pigeon circovirus) H5N1 Hong Kong virus through the nasal passage. Researchers saw no clinical signs of virus from infected pigeons and did not observe any lesions. Viral antigens were absent in the organ tissues taken from these birds.
Highly pathogenic turkey isolates
Slemons and Easterday 1972 showed that the highly pathogenic turkey isolate of H5N9 AIV was present in 2 of 19 experimentally inoculated pigeons. Researchers could not determine if the virus was directly from the inoculum or if the pigeons became infected.
Pigeons inoculated oculonasally with H7N9 or H7N7 in a 2014 Kalthoff et al. study were infected with both viruses and shed low levels between days two and seven post-inoculation. Most shedding was from the respiratory tree although H7N7 was also present in feces. Researchers did not find viral antigens in internal organs.
H5N1 Egypt virus
Only one study looked at a virus recovered from a naturally infected pigeon (H5N1, clade 2.2.1/C, Egypt). This virus caused neurological signs and greenish diarrhea when researchers experimentally infected birds. Infected birds shed very little virus during the experimental study.
Surveys of wildlife including 480 pigeons and doves after the 1983 PA AI outbreak did not result in isolations of AIV. The Ck/PA H5N2 virus did not replicate or elicit antibodies in experimentally infected pigeons. Another 309 pigeons surveyed during the outbreak had no antibodies to the H5N2 virus.
Recent bird surveys of live bird markets in New York have not revealed any pigeons with antibodies to AIV. A few isolations were made from bird-dropping boards under pigeon cages in the Hong Kong markets. In genetic comparisons, these viruses are similar to those isolated from silkie chickens, quail, and other chickens in the live bird markets from Hong Kong. No experimental inoculations of pigeons have been done with these isolates.
A sublineage of H5 viruses did cause an outbreak of HPAI in pigeons in Egypt. This virus was similar to viruses concurrently circulating in backyard poultry flocks and ducks and causing human infections. Two squabs (40 days old) from a backyard free-ranging flock of 50 of various ages, were submitted and diagnosed with HPAI. The flock had experienced sudden death (50 percent mortality), neurologic signs, and greenish diarrhea.