Avian metapneumovirus detected in the U.S.

February 29, 2024

On Jan. 23, the National Veterinary Services Laboratories (NVSL) confirmed avian metapneumovirus (aMPV) subtype B in samples from a National Animal Health Laboratory Network (NAHLN) laboratory. These samples originated from turkeys and broilers in Virginia and North Carolina. We are also hearing of cases in Pennsylvania and South Carolina. APHIS also confirmed, on Feb. 1, the presence of aMPV subtype A in turkeys in California from samples collected between November and December 2023. While aMPV subtype C was known to exist in the U.S., mainly concentrated in Minnesota from 1997 to 2000, subtypes A and B had yet to be identified in the U.S.

Over the past few months, diagnostic laboratories in several states have indicated increased serologic positives using a pan-aMPV assay. The positive serologic samples have increased since the early fall of 2023, but further subtyping has not been requested, and the serologic assays do not distinguish among the subtypes. These findings have been associated with high mortality events in turkeys and broilers accompanied by respiratory or reproductive clinical signs. APHIS does not expect significant trade implications from these detections nor recommends or anticipates any regulatory response activities to restrict movement or stamp out the disease.

The Center for Veterinary Biologics (CVB) has received at least one application to import a killed vaccine but has not yet received all the required information. If vaccines meet requirements for use, the CVB will contact State Animal Health officials to approve the import into and use of any vaccine in their state as part of Title 9, Code of Federal Regulations103.3 research and evaluation permitting process. On Feb. 6, 2024, CVB published Notice No. 24-03 to inform interested parties that CVB accepts product license and import permit applications for vaccines and diagnostic products for aMPV.

Considering these detections, APHIS recommends the following:

  • APHIS encourages laboratories receiving samples with compatible clinical signs, including high mortality and reproductive losses, to consider conducting testing for aMPV and report positive PCR or virus isolation findings to the state animal health official (SAHO) where the positive flock is located.
  • APHIS will send additional guidance to SAHOs to report findings voluntarily to support national monitoring. APHIS’ requested information will include test type, production type, test result date, and clinical signs in reports, and provide a tool to share this information.
  • While confirmatory testing by NVSL is not necessary for reporting, NVSL will support virus monitoring efforts by offering whole genome sequencing at no cost to the submitter for samples with Ct values of 30 and lower.