A Systematic Review and Meta-Analysis of the Seroprevalence of Influenza A(H9N2) Infection among Humans

Salah Uddin Khan, Benjamin D. Anderson, Gary L. Heil, Song Liang, Gregory C. Gray

Research output: Contribution to journalReview articlepeer-review

60 Scopus citations

Abstract

Introduction. Given that influenza A(H9N2) is recognized as a pandemic threat, we evaluated the overall burden of influenza A(H9N2) infections among avian-exposed human populations. Methods. We performed a systematic search of PubMed, AGRICOLA, and CAB Abstracts databases for literature published during 1997-2013. Studies reporting serological evidence of human influenza A(H9N2) infection among avian-exposed populations were included. We used a World Health Organization (WHO)-recommended case definition for serological evidence of infection based on results of hemagglutination inhibition (HI) and microneutralization (MN) assays. We calculated overall seroprevalence through a random effects meta-analysis model. Results. Seroprevalence data reported by the studies ranged from 1% to 43% (median, 9%) by HI, which was not significantly different from the seroprevalence estimated through the WHO-recommended case definition (median, 1.3%; range, 0.5%-42.6%). Reported seroprevalence by MN ranged from 0.6% to 9% (median, 2.7%), which was greater than the seroprevalence estimated through the WHO-recommended case definition (median, 0.3%; range, 0.1%-1.4%). Conclusions. A small proportion of avian-exposed humans had evidence of influenza A(H9N2) infection. As the virus has a near global distribution in poultry, it seems likely that present surveillance efforts are missing mild or asymptomatic infections among avian-exposed persons. It seems prudent to closely monitor avian-exposed populations for influenza A(H9N2) infection to provide prepandemic warnings.

Original languageEnglish (US)
Pages (from-to)562-569
Number of pages8
JournalJournal of Infectious Diseases
Volume212
Issue number4
DOIs
StatePublished - Aug 15 2015
Externally publishedYes

Keywords

  • H9N2 subtype
  • hemagglutination inhibition test
  • influenza Avirus
  • meta-analysis
  • microneutralization test
  • seroprevalence
  • systematic review

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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