A national study of individuals who handle migratory birds for evidence of avian and swine-origin influenza virus infections.

BACKGROUND

Persons with occupational or recreational exposure to migratory birds may be at risk for infection with highly pathogenic avian influenza and other avian influenza viruses since wild birds are the natural reservoir of influenza A. Additionally, bird handlers may host avian and swine-origin influenza (pH1N1) virus co-infections, which generate reassortant viruses with high pathogenicity in mammals.

OBJECTIVES

We assessed the prevalence of avian and swine influenza viruses in US-based bird handlers and estimated their exposure to different orders of wild birds including waterfowl (Anseriformes), songbirds (Passeriformes), and shorebirds (Charadriiformes).

STUDY DESIGN

Cross-sectional serologic survey accompanied by a questionnaire to estimate behavioral risk factors. This is first survey of US-based bird handlers who also work at international sites.

RESULTS

401 participants were recruited and tested over the course of 3 years. One participant with occupational exposure to migratory birds had evidence of past infections with a H5N2 virus antigenically related to A/Nopi/MN/07/462960-02, which is the first case of this influenza subtype in a human host associated with exposure to wild rather than domestic birds. We detected no avian and swine-origin influenza virus co-infections. The exposure of bird handlers to songbirds was four times greater than to shorebirds or waterfowl.

CONCLUSIONS

Though rare, the transmission of avian influenza viruses from migratory birds to US-based bird handlers has potentially significant public health and economic consequences.