What causes H5N1 avian influenza? Lay perceptions of H5N1 aetiology in South East and East Asia

Background Health education to reduce population poultry exposures has limited effect. Lay beliefs about H5N1 highly pathogenic avian influenza (HPAI) causes could provide insights helpful for improving public health interventions. Methods Qualitative interviews of poultry farmers, retailers, market stall holders and consumers in Hong Kong (n = 20), Guangzhou (n = 25), Vietnam (n = 38) and Thailand (n = 40) were conducted using purposive sampling and analysed using ethnographic principles. Results Each location produced three comparable themes: 'viruses': HPAI exemplified a periodic, natural, disease process therefore, deserving little concern. For some, science had 'discovered' something long known to farmers and lived with for generations. Others believe the virus to be new. Viral ecology was reasonably well understood among farmers, but less so by retailers and consumers; 'husbandry practices' included poor hygiene, overcrowding and industrial farming, modern commercial feed and veterinary drugs; 'vulnerability factors' included uncontrollable 'external' explanations involving the weather, seasonal changes, bird migrations and pollution. Conclusions Lay explanations were generally ecologically consistent. Nonetheless, beliefs that HPAI is a normal, recurrent process, external factors and roles of industrialized poultry rearing countered health worker claims of H5N1 seriousness for smallholders. These causal beliefs incorporate contemporary models of H5N1 ecology, but in a manner that contradicts public health efforts at control.