Serosurvey of Pandemic Influenza A (H1N1) 2009 and Avian Influenza A (H5N1) Infections in Humans and Wildlife in Zoos and Wildlife Breeding Centers, Thailand, 2011

Abstract

The outbreaks of pandemic influenza A (H1N1) 2009 and avian influenza (H5N1) as well as other emerging diseases have been seriously occurring around the world. This study was to define the prevalence of pandemic influenza A (H1N1) 2009 and avian influenza (H5N1) infections in wildlife animals and individuals working with captive wildlife and to identify risk factors of the influenza infection.This cross-sectional serosurvey included 130 participants from Dusit zoo, Songkhla zoo, Khao Pratub Chang Wildlife Breeding Center (WBC), Ratchaburi province and Phattalung WBC. Haemagglutination inhibition test was used to screen for antibody (Ab) against avian influenza (H5N1) and influenza A (H1N1) 2009. In animals, samples of serums, swabs and tissues were collected to identify immunity of avian influenza H5N1 and influenza A (H1N1) 2009 both HI titer and viral isolation. The result showed Ab to influenza A (H1N1) 2009 with HI titer ≥ 1:40 in 11 percent but antibody for avian influenza (H5N1) was not found. In two tigers in a zoo antibodies were found against influenza A (H1N1) 2009 with HI titer ≥ 1: 40. Risk factors, associated with ARI, included ARI in family members (adjusted OR 3.30 95% CI 1.37, 7.90); ARI in coworkers (adjusted OR 2.90. 95% CI 1.08, 7.72). A lower prevalence of Ab to influenza A (H1N1) 2009 than normal population possibly indicates that the participants not being a risk group for the infection as they were in a working age group with habitat in isolated rural areas. Ab to influenza A H1N1 2009 in zoo keepers and animals were reported in the same establishment and hence validating plausible viral transmission.