Environmental and anthropogenic risk factors for highly pathogenic avian influenza subtype H5N1 outbreaks in Romania, 2005-2006

The association between highly pathogenic avian influenza (HPAI) subtype H5N1 outbreak risk in poultry in 161 Romanian villages (October 2005 to June 2006) and environmental and anthropogenic factors was investigated. Village outbreak risk was associated with a village being < 5 km from a major road (odds ratio [OR] 5.27, 95% confidence interval [CI] 1.21-22.9) or a river/stream (OR 1.97, 95% CI 1.06-3.72). Outbreak risk in the first part of the epidemic was associated with a village being < 5 km from a major road (OR 3.31, 95% CI 1.10-9.98) or a regularly flooded land area (OR 5.08, 95% CI 1.08-23.9); whereas outbreak risk in the second part of the epidemic was associated with a village being < 5 km from a river/stream (OR 5.5, 95% CI 1.69-18.9). Results suggest that both environmental and anthropogenic factors influence the risk of HPAI subtype H5N1 outbreaks in village poultry populations.