Longitudinal Analysis of Influenza A(H5) Sero-Surveillance in Myanmar Ducks, 2006–2019

Abstract

Between 2006 and 2019, serological surveys in unvaccinated domestic ducks reared outdoors in Myanmar were performed, using a haemagglutination inhibition (HI) test, to confirm H5 avian influenza virus circulation and assess temporal and spatial distribution. Positive test results occurred every year that samples were collected. The annual proportion of positive farms ranged from 7.1% to 77.2%. The results revealed silent/sub-clinical influenza A (H5) virus circulation, even in years and States/Regions with no highly pathogenic avian influenza (HPAI) outbreaks reported. Further analysis of the 2018/19 results revealed considerable differences in seroconversion rates between four targeted States/Regions and between years, and showed seroconversion before and during the sampling period. By the end of the trial, a high proportion of farms were seronegative, leaving birds vulnerable to infection when sold. Positive results likely indicate infection with Gs/GD/96-lineage H5Nx HPAI viruses rather than other H5 subtype low-pathogenicity avian influenza viruses. The findings suggested persistent, but intermittent, circulation of Gs/GD/96-lineage H5Nx HPAI viruses in domestic ducks, despite the veterinary services’ outbreak detection and control efforts. The role of wild birds in transmission remains unclear but there is potential for spill-over in both directions. The findings of this study assist the national authorities in the design of appropriate, holistic avian influenza control programs.

Special Issue “Ecology of Influenza A Viruses”: Editorial

“…These two novel viruses contained an H7 hemagglutinin gene phylogenetically related to contemporary strains from Mongolia, Georgia, and Ukraine and predated the detection of this H7 LPAIV sublineage in East Asia in 2019, but more importantly, their polymerase and nucleoprotein segments clustered with contemporary H5 HPAI (clade 2.3.4.4b) viruses, indicating the H7 LPAIV subtype’s large dispersal and its potential for gene reassortment. A longitudinal analysis of influenza A(H5) sero-surveillance performed in ducks reared outdoors in Myanmar is the second research article published in this Special Issue, which was written by Mon et al [ 14 ]. This sero-surveillance study was carried out between 2006 and 2019 on unvaccinated domestic ducks by collecting 78,804 samples from 1817 farms/flocks in selected States and Regions of Myanmar with the aim of confirming H5 AIVs’ circulation and assessing the temporal and spatial distribution of infections.…”