Abstract:
Ducks are the natural reservoir of influenza A virus and the central host for the avian
influenza virus (AIV) subtype H5N1, which is highly pathogenic. Semi-scavenging domestic ducks
allow for the reemergence of new influenza subtypes which could be transmitted to humans. We
collected 844 cloacal swabs from semi-scavenging ducks inhabiting seven migratory bird sanctuaries
of Bangladesh for the molecular detection of avian influenza genes. We detected the matrix gene
(M gene) using real-time RT–PCR (RT–qPCR). Subtyping of the AIV-positive samples was performed
by RT–qPCR specific for H5, H7, and H9 genes. Out of 844 samples, 21 (2.488%) were positive for
AIV. Subtyping of AIV positive samples (n = 21) revealed that nine samples (42.85%) were positive
for the H9 subtype, five (23.80%) were positive for H5, and seven (33.33%) were negative for the three
genes (H5, H7, and H9). We detected the same genes after propagating the virus in embryonated
chicken eggs from positive samples. Semi-scavenging ducks could act as carriers of pathogenic AIV,
including the less pathogenic H9 subtype. This can enhance the pathogenicity of the virus in ducks
by reassortment. The large dataset presented in our study from seven areas should trigger further
studies on AIV prevalence and ecology.
