A cross-sectional study of avian influenza A virus in Myanmar live bird markets: Detection of a newly introduced H9N2?

Abstract

Background: Zoonotic influenza surveillance in Myanmar is sparse, despite the risks of introduction of such viruses from neighboring countries that could impact the poultry industry and lead to spillover to humans.

Methods: In July and August 2019, our multi-institutional partnership conducted a One Health-oriented, cross-sectional surveillance (weekly for 3 weeks) for influenza A and influenza D viruses at the three largest live bird markets in Yangon, Myanmar.

Results: The 27 bioaerosols, 90 bird cage swabs, 90 bird oropharyngeals, and 90 human nasopharyngeal samples yielded molecular influenza A detections in 8 bioaerosols (30.0%), 16 bird cages (17.8%), 15 bird oropharyngeals (16.7%), and 1 human nasopharyngeal (1.1%) samples. No influenza D was detected. Seven of the influenza A virus detections were found to be subtype A/H9N2, and one human nasopharyngeal sample was found to be subtype A/H1pdm. Among all IAV-positive samples, three of the A/H9N2-positive samples yielded live viruses from egg culture and their whole genome sequences revealing they belonged to the G9/Y280 lineage of A/H9N2 viruses. Phylogenetic analyses showed that these A/H9N2 sequences clustered separately from A/H9N2 viruses that were previously detected in Myanmar, supporting the notion that A/H9N2 viruses similar to those seen in wider Southeast Asia may have been introduced to Myanmar on multiple occasions.

Conclusions: These findings call for increased surveillance efforts in Myanmar to monitor for the introduction of novel influenza viruses in poultry, as well as possible reassortment and zoonotic virus transmission.

Keywords: H9N2; Myanmar; One Health; influenza virus; live bird market.

FIGURE 1

Phylogeographic map of Southeast Asia and maximum likelihood phylogenetic analysis of hemagglutinin (HA) and neuraminidase (NA) segments of isolated A/H9N2 viruses. Sampling sites are indicated by asterisks. Adjacent countries are color‐coded by reported A/H9N2 lineage detections. A/H9N2 viruses sequenced in this study are labeled with red circles. Viruses previously identified in Myanmar are colored blue.