Little evidence of avian or equine influenza virus infection among a cohort of Mongolian adults with animal exposures, 2010-2011.
Authors: Khurelbaatar Nyamdavaa, Krueger Whitney S, Heil Gary L, Darmaa Badarchiin, Ulziimaa Daramragchaa, Tserennorov Damdindorj, Baterdene Ariungerel, Anderson Benjamin D, Gray Gregory C
Journal: PloS one
Summary
# Editorial Summary Mongolia's migrating bird populations and domestic horses harbour both avian and equine influenza viruses, yet the actual risk of zoonotic transmission to humans remains poorly characterised. Researchers enrolled 439 Mongolian adults with occupational animal exposure in a 24-month prospective cohort study, collecting serum samples at baseline, 12 and 24 months, whilst monitoring participants monthly for acute influenza-like illness and performing reverse-transcription polymerase chain reaction testing on respiratory swabs. Although 36 of 100 acute respiratory infections investigated tested positive for influenza A virus, none yielded evidence of avian or equine influenza; serological analysis detected only low-titre antibodies (all <1:80) against equine H3N8 (21 participants) and various avian subtypes including H6N1, H9N2 and H10N4 (16 participants combined), with no statistical association between these low titres and reported animal exposures, suggesting cross-reactivity with seasonal human influenza viruses rather than true zoonotic infection. These findings indicate that despite documented circulation of AIV and EIV in Mongolia's wildlife and equine populations, natural transmission to humans with regular animal contact appears considerably rarer than would be predicted from viral prevalence alone. For equine professionals, this supports a measured rather than alarmist approach to routine exposure, though continued surveillance remains warranted given the potential for viral evolution and the unpredictable nature of zoonotic spillover events.
Read the full abstract on PubMed
Practical Takeaways
- •Equine professionals working in Mongolia with high animal contact appear to have minimal actual risk of acquiring EIV infection despite virus circulation in the horse population
- •Low antibody titers to equine and avian influenza in exposed populations are more likely cross-reactive responses to seasonal flu than true zoonotic infection
- •While AIV and EIV circulate among animals in Mongolia, the transmission risk to occupationally exposed humans appears negligible based on this prospective surveillance
Key Findings
- •Over 24 months of follow-up, 36 of 100 ILI investigations (36%) yielded influenza A infections by rRT-PCR, but none showed evidence of AIV or EIV
- •Serological testing of 437 participants revealed 37 (8.5%) with detectable antibody titers to equine or avian influenza viruses, but all titers were <1:80 and not associated with animal exposure
- •Low-level seroreactivity against AIV or EIV was likely due to cross-reacting antibodies from seasonal human influenza viruses rather than true zoonotic infection
- •Despite documented circulation of AIV and EIV among wild birds and horses in Mongolia, prospective cohort showed little clinical or serological evidence of transmission to humans with animal exposures