There are 12 recognized serotypes of avian paramyxoviruses (PMV-1 to PMV-12). Newcastle disease virus is the most important pathogen of this group for poultry, but PMV-2, -3, -6, and -7 are occasionally associated with disease in chickens and turkeys. The most recent serotypes (PMV-10, -11, and -12) were isolated from Rockhopper penguin (Eudyptes chrysocome) in the Falkland Islands, Common Snipe (Gallinago gallinago) in France, and Eurasian Widgeon (Anas penelope) in Italy, respectively, and were the first new serotypes in >30 yr.
PMV-2 has been isolated from wild birds, mainly passerines, and caged psittacine species. Primary infections in poultry are believed to be the result of contact with wild birds. The method of transmission to chickens or turkeys is unclear. PMV-3 has been isolated from imported exotic and other bird species held in captivity. Psittacines appear to be the primary host, although PMV-3 will spread among passerines in captivity. There are no reports of isolation of PMV-3 from wild birds. The method of transmission among turkeys is unclear, and spread within a flock is usually slow.
Infections by PMV-2, -3, -6, and -7 in turkeys have produced mild to severe respiratory disease, drops in egg production, reduced hatchability and infertility of eggs, and increased numbers of white-shelled eggs. Infection with PMV-2 has produced mild respiratory disease in chickens, but PMV-2 infection is usually most severe in turkeys, especially breeders. Infection is more severe when accompanied by secondary pathogens.
Most diagnoses are made by clinical signs and confirmed by serology. PMV-2, -3, -6, and -7 can be isolated from oropharyngeal or cloacal swabs, or tissue samples from infected birds by inoculating the allantoic cavity of 8- to 10-day-old embryonating chicken eggs. Confirmation of the virus as PMV can be done by hemagglutination inhibition tests with specific antiserum to individual serotypes. However, PMV-1 (Newcastle disease virus) and PMV-3 may cross-react in hemagglutination inhibition tests (and in other serologic tests such as ELISA), which causes interpretation problems in vaccinated birds. Birds vaccinated against Newcastle disease show a rise in hemagglutination inhibition titers to both viruses if subsequently infected with PMV-3.
No vaccines are available for PMV-2, -6, and -7. Inactivated oil-emulsion vaccines against PMV-3 have been used in turkey breeder flocks. These are injected twice, 4 wk apart, before the birds begin to lay (usually when 20–24 wk old). The risk of introducing PMV-2 and other paramyxoviruses from wild birds may be minimized by bird-proofing poultry houses and using good hygiene and biosecurity practices. Treatment of secondary bacterial infections with antibiotics has had some success. PMV-3 appears to spread slowly.
No human infections have been reported for PMV-2 to PMV-12 viruses.