Detection of Low Pathogenicity Influenza A(H7N3) Virus During Duck Mortality Event, Cambodia, 2017

Abstract

In January 2017, an estimated 3,700 (93%) of 4,000 Khaki Campbell ducks (Anas platyrhynchos domesticus) died in Kampong Thom Province, Cambodia. We detected low pathogenicity avian influenza A(H7N3) virus and anatid herpesvirus 1 (duck plague) in the affected flock; however, the exact cause of the mortality event remains unclear.

Keywords: AIV; Cambodia; H7N3; LPAI; LPAIV; avian; ducks; influenza; low pathogenicity; mortality event; poultry; viruses; zoonoses.

Figure 1

Location of duck mortality event and detection of influenza A(H7N3) virus in Kampong Thom Province (gold shading), Cambodia, January 2017. Open circle indicates exact location of the mortality event.

Figure 2

Phylogenetic analysis of the H7 hemagglutinin (HA) gene (A) and N3 neuraminidase (NA) gene (B) of influenza viruses isolated from ducks in Kampong Thom Province, Cambodia (boldface), and reference isolates. Trees were generated using the maximum-likelihood method based on the general time-reversible model. Bootstrap values (n = 500) >70 are indicated. Light pink shading indicates strains from Eurasia, blue shading indicates strains from North and South America, and dark pink shading indicates H7N9 strains from China. Black dots indicate strains from human infections. GenBank accession numbers are provided for reference isolates. Scale bars indicate nucleotide substitutions per site.