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Avian Metapneumovirus (aMPV), also known as Swollen Head Syndrome (SHS), Avian Rhinotracheitis (ART), Turkey Rhinotracheitis (TRT), or Avian Pneumovirus (APV), has been reported in turkeys, turkey breeders, broilers, broiler breeders, commercial egg layers, and layer breeders. The first Subtype B outbreak was observed in Fall/Winter 2023 in North Carolina, alongside suspicions of Subtype A in California.
Currently, Subtype B has been confirmed in turkeys, broiler chickens, breeders, egg-layer chickens, and breeders across NC, SC, GA, VA, WV,PA, DE, and MI. Subtype A was first confirmed in CA (turkeys) and TX (broilers and breeders). "Confirmed" positive cases require two or more positive tests, including clinical signs, serology, PCR, and histopathology. By May, aMPV had spread through Midwest poultry states from Arkansas to Minnesota, with the most recent confirmation in an Iowa turkey flock with Subtype A.
This virus causes severe respiratory disease, initially presenting with sinusitis (nasal discharge, snicking, coughing, head shaking, caked nares), swollen heads/eyes (conjunctivitis), and mild airsacculitis. Affected birds may initially display puffy, wet eyes, foamy suds in the eye corners, a dirty ring around the eye, reduced feed and water consumption, signs of chill, and eventually swollen sinuses. Breeders may also exhibit egg-drop and neurologic signs such as torticollis. Clinical signs can vary from mild to severe.
In laboratory conditions, the virus can survive for at least2-4 weeks at room temperature (68°F), 4-12 weeks when refrigerated (39°F), 2days at 98°F, less than 72 hours at 100°F, and 6 hours at 122°F.Map of aMPV confirmations in poultry as of May 10, 2024.
AMPV is rapidly spreading throughout the USA. Both A and B subtypes were confirmed in both California and NC in January 2024 and have since spread to most poultry-producing states within 4 months. In the past month alone, states and one country have confirmed cases, including Iowa, Tennessee, Kentucky, Minnesota, Oklahoma, and Canada. AMPV has quickly infected turkeys, broiler chickens, egg-layer chickens, and breeder poultry across the nation.(Map attached below.)
There's an urgent need for both live and killed vaccines targeting subtypes A and B in both chicken and turkey populations. Importing commercial vaccines from outside the US via CVB Notice No. 24-03 seems to be the quickest solution. Solely relying on killed vaccines isn't practical for commercial turkey and broiler chicken flocks. While US labs have limited successful isolations subtype B virus, and only one subtype A, from turkeys and chickens, the current regulatory pathway for a USDA-approved live vaccine will take 4 to 6 years. In the meantime, autogenous killed vaccines can be produced on a shorter timeline, but they'll primarily protect broiler breeders, turkey breeders, and egg layers from production losses and bird mortality. Meat birds urgently need live vaccine options too.
Wild bird surveillance is crucial as the introduction of AMPV has not been confirmed. Wild birds could potentially spread the infection or represent the source of the first A and B commercial poultry infections. The USDA's National Wildlife Services has been systematically collecting samples of hunter-harvested waterfowl to monitor for HPAI. Historic samples are archived and available for research. Proposals could be accepted to evaluate these samples for AMPV based on date and location. Additionally, the recent announcement regarding the re-establishment of the National Wildlife Services Advisory Committee underscores the importance of this surveillance effort.
