Avian paramyxovirus types 2–28 are harbored predominantly in wild bird populations. Infections of poultry with these viruses are usually subclinical. Occasionally, types 2, 3, 6, and 7 have caused mild disease in chickens, turkeys, and ostriches. Diagnosis is based on laboratory confirmation via detection of paramyxovirus RNA or antibodies or by virus isolation. Vaccines are available for some avian paramyxovirus types, but not all. Good biosecurity practices are the chief strategy for preventing disease.
Although avian paramyxovirus type 1 (APMV-1; Orthoavulavirus javaense) infections have substantial impact on poultry, infections with other APMV types have been reported mainly in wild birds. Occasionally, some of these viruses have been isolated from poultry with respiratory disease or decrease in egg production.
The animal health and economic importance of APMV viruses is considered low, and it is not known whether isolations from sick poultry are incidental findings or whether these infections have contributed to disease.
Specialized and reference laboratories can identify and subtype APMVs. Vaccines against APMV-3 exist in Europe and the US.
Etiology and Epidemiology of Other Avian Paramyxovirus Infections
Advances in genome sequencing and enhanced surveillance programs have resulted in identification of 18 previously unreported avian paramyxovirus types since the year 2000 (1). The International Committee on Taxonomy of Viruses (ICTV) recognizes 28 types of APMVs: APMV-1 to APMV-28. For poultry, Newcastle disease virus (APMV-1) is the most important pathogen of this group; however, APMV-2, -3, -6, and -7 are occasionally associated with disease in chickens, turkeys, and ostriches.
APMVs have been historically grouped primarily on the basis of their hemagglutination inhibition reactivity with serotype‐specific sera. Currently, paramyxovirus species and isolates are defined by genomic sequence similarities.
Experimental infections and pathogenicity studies in chickens with most APMV types (aside from APMV-1) did not produce clinical signs of disease. Types APMV-6 and -7 caused mild respiratory disease and affected egg production in turkeys (2).
Avian paramyxoviruses have been isolated from different wild birds worldwide. Primary infections in poultry are believed to be the result of contact with wild birds. Although the method of transmission to chickens or turkeys is unclear, the fecal-oral route is considered to play a primary role. Once these viruses are introduced in a turkey flock, their transmission within the flock is usually slow.
Some APMVs are adapted to specific wild bird species and can cause serious disease; one example is APMV-5 infection in budgerigars, which can cause acute onset of GI and neurological signs with high mortality rates.
Clinical Findings of Other Avian Paramyxovirus Infections
Because clinical signs of avian paramyxovirus infection are rarely observed, estimating the incubation period is challenging. Infections are typically restricted to the respiratory tract and sometimes the digestive tract.
APMV infections are more severe when accompanied by secondary pathogens, and it is not clear whether APMVs play a role as primary pathogen or cause underlying conditions that are exacerbated by infection with other viruses and bacteria.
Clinical signs of APMV infection vary by the virus type (2):
APMV‐2, ‐3, and ‐6 infections have been associated with clinical signs in turkeys, including mild to severe respiratory disease, decreased egg production, decreased hatchability and infertility of eggs, and increased numbers of white-shelled eggs.
Infection with APMV-2 has produced mild respiratory disease in chickens; however, APMV-2 infection is usually most severe in turkeys, especially breeders. Sinusitis has been documented in turkeys infected with APMV-2.
Lesions due to APMV infection are rare; enlargement of the pancreas with focal necrosis has been reported in chickens infected with APMV-3. APMV‐3 has also been isolated from farmed ostriches in South Africa.
Turkeys with APMV‐7 infection presented with rhinitis and airsacculitis. Enlarged pancreas and airsacculitis have also been observed in turkeys infected with APMV-7.
Enlarged spleens and livers have been reported in parakeets and doves infected with APMV-3 and APMV-7, respectively.
Diagnosis of Other Avian Paramyxovirus Infections
Detection of avian paramyxovirus RNA
Detection of virus-specific antibodies
Virus isolation
Most diagnoses of avian paramyxovirus infection are made by laboratory confirmation after initial suspicion based on clinical signs. APMVs can be isolated from oropharyngeal or cloacal swabs or from tissue samples from infected birds by inoculation of the allantoic cavity in SPF embryonated chicken eggs 9–11 days old. The virus can be confirmed as APMV via hemagglutination inhibition tests with antiserum specific to individual serotypes, by specific real-time RT-PCR assay, or by genomic sequencing.
Of note, APMV-1 (Newcastle disease virus) can cross-react in hemagglutination inhibition (HI) tests (and in other serological tests, such as ELISA) with both APMV-3 and APMV-7, causing test result interpretation problems in vaccinated birds. Therefore, any unexpected HI results should be verified to ensure that the results are not due to cross-reaction.
Pearls & Pitfalls
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Differential diagnoses for APMV infections include infections with other pathogens that cause similar respiratory disease, such as low-pathogenicity avian influenza, infectious bronchitis, and avian metapneumovirus.
Prevention and Control of Other Avian Paramyxovirus Infections
Biosecurity
Limited vaccination for some APMV types
Bird-proofing poultry houses
Good hygiene
Because vaccines are not available against many avian paramyxoviruses, good biosecurity practices are the chief strategy for preventing disease.
No vaccines against APMV-2, -6, and -7 are available. Inactivated virus oil-adjuvanted vaccines against APMV-3 have been used in turkey breeder flocks; these are injected twice, 4 weeks apart, before the birds begin to lay (usually at 20–24 weeks old).
Autogenous vaccines have been tested for different APMV types, but they are not widely used.
The risk of introducing APMVs from wild birds can be minimized by bird-proofing poultry houses and using good hygiene and biosecurity practices. Treatment of secondary bacterial infections with antimicrobials has had some success.
Zoonotic Risk of Other Avian Paramyxovirus Infections
No infections in humans have been reported for avian paramyxovirus types 3–28 (APMV-3 through APMV-28). Serological evidence of APMV-2 in humans has been reported but likely has no public health importance (3). APMV-1 (Newcastle disease virus) has a low public health risk.
Key Points
Avian paramyxovirus types APMV-2 through APMV-28 are found predominantly in wild birds, and most documented infections of chickens by types 2–28 are subclinical.
APMV-2, -3, -6, and -7 have occasionally been associated with disease in chickens, turkeys, and ostriches.
The clinical course of APMV infections can be worsened by secondary infection.
For More Information
Suarez DL, Miller PJ, Koch G, Mundt E, Rautenschlein S. Newcastle disease, other avian paramyxoviruses, and avian metapneumovirus infections. In: Swayne DE, Boulianne M, Logue CM, McDougald CR, Nair V, Suarez DL, et al, eds. Diseases of Poultry. 14th ed. Wiley-Blackwell; 2020;111-166.
Alexander DJ. Newcastle disease and other avian paramyxoviruses. Rev Sci Tech. 2000;19(2):443-462.
Gieger S, Furmaga E. Avian paramyxoviruses (non-notifiable). Organisation International des Epizooties (OIE [aka WOAH]). Last updated 2020. OIE Technical Disease Cards.
References
Young KT, Stephens JQ, Poulson RL, et al. Putative novel avian paramyxovirus (AMPV) [sic] and reidentification of APMV-2 and APMV-6 to the species level based on wild bird surveillance (United States, 2016–2018). Appl Environ Microbiol. 2022;88(11):e00466-22. doi:10.1128/aem.00466-22
Suarez DL, Miller PJ, Koch G, Mundt E, Rautenschlein S. Newcastle disease, other avian paramyxoviruses, and avian metapneumovirus infections. In: Swayne DE, ed. Boulianne M, Logue CM, McDougald CR, Nair V, Suarez DL, associate eds. Diseases of Poultry. 14th ed. Wiley Blackwell; 2020;111-166. doi:10.1002/9781119371199.ch3
Fleury HJ, Bonnici JF, Babin M, Du Pasquier P, Samb A. Serological evidence of human infection with the paramyxovirus Yucaipa in Senegal, West Africa. Am J Trop Med Hyg. 1984;33(1)190-191. doi:10.4269/AJTMH.1984.33.190
