Evidence for subclinical avian influenza virus infections among rural Thai villagers.

Background: Regions of Thailand reported sporadic outbreaks of A/H5N1 highly pathogenic avian influenza (HPAI) among poultry between 2004 and 2008. Kamphaeng Phet Province, in north-central Thailand had over 50 HPAI poultry outbreaks in 2004 alone, and 1 confirmed and 2 likely other human HPAI infections between 2004 and 2006.

Methods: In 2008, we enrolled a cohort of 800 rural Thai adults living in 8 sites within Kamphaeng Phet Province in a prospective study of zoonotic influenza transmission.