Risk factors for H7 and H9 infection in commercial poultry farm workers in provinces within Pakistan

Abstract

A cross sectional survey was conducted involving 354 farm poultry workers on 85 randomly selected commercial poultry farms in high density poultry farm areas in Pakistan to estimate the sero-prevalence of H5, H7 and H9 and to identify the potential risk factors for infection with the avian influenza virus. A haemagglutination inhibition test titre at 1:160 dilution was considered positive, based on WHO guidelines. The estimated sero-prevalence was 0% for H5, 21.2% for H7 and 47.8% for H9. Based on a generalized linear mixed model, the significant risk factors for H7 infection were area, type of farm and age of poultry worker. Risk of infection increased with the age of poultry workers. Compared with broiler farms, breeder farms presented a greater risk of infection (odds ratio [OR]=3.8, 95% confidence interval [CI]: 1.4, 10.1). Compared with the combined Khyber Pakhtunkhwa Province and Federal area, North Punjab had higher observed biosecurity measures and presented a lesser risk of infection (OR=0.3, 95% CI 0.1, 0.9). Biosecurity should therefore be enhanced (especially in breeder farms) to reduce the occupational risks in poultry farm workers and to decrease the risk of emergent human-adapted strains of AI H7 and H9 viruses.

Keywords: Avian influenza; H7; H9; Poultry farm workers; Serological-survey.