Risk factors for human avian influenza (A/H5N1) infection in Vietnam 2004

ABSTRACT

We conducted a matched case-control study with 28 laboratory-confirmed cases of influenza A/H5N1 (by RT-PCR assay) and 106 controls in Vietnam in the year 2004 (case to control ratio is 14). Matching criteria includes sex, age (the difference is less than 2 year) and location of living. Main results are as follow (1) Two poultry-related risk factors of human avian influenza A/H5N1 are direct handling of ill/dead poultry, and having ill/dead poultry in household. (2) Unavaillable indoor water-tap in household is signifficantly associated with human influenza A/H5N1. This is an suggestion to the role of hygiene and invironment-related factors, but the mechanism is still not clear. (3) Exposure to healthy poultry, domestic animals and patients with acute respiratory infections seems not to be a risk factor for avian influenza infection in the year 2004. Further studies with integrated designs are needed to describe mode(s) of transmission and identify sources of infection.