No evidence for zoonotic transmission of H3N8 canine influenza virus among US adults occupationally exposed to dogs

OBJECTIVES: The zoonotic potential of H3N8 canine influenza virus (CIV) has not been previously examined; yet considering the popularity of dogs as a companion animal and the zoonotic capabilities of other influenza viruses, the public health implications are great. This study aimed to determine the seroprevalence of antibodies against CIV among a US cohort. DESIGN: A cross-sectional seroepidemiological study was conducted between 2007 and 2010. SETTING: Recruitments primarily occurred in Iowa and Florida. Participants were enrolled at dog shows, or at their home or place of employment. SAMPLE: Three hundred and four adults occupationally exposed to dogs and 101 non-canine-exposed participants completed a questionnaire and provided a blood sample. MAIN OUTCOME MEASURES: Microneutralization and neuraminidase inhibition assays were performed to detect human sera antibodies against A/Canine/Iowa/13628/2005(H3N8). An enzyme-linked lectin assay (ELLA) was adapted to detect antibodies against a recombinant N8 neuraminidase protein from A/Equine/Pennsylvania/1/2007(H3N8). RESULTS: For all assays, no significant difference in detectable antibodies was observed when comparing the canine-exposed subjects to the non-canine-exposed subjects. CONCLUSION: While these results do not provide evidence for cross-species CIV transmission, influenza is predictably unpredictable. People frequently exposed to ill dogs should continually be monitored for novel zoonotic CIV infections.