Outbreak of cutaneous anthrax in Musalimadugu village, Chittoor district, Andhra Pradesh, India, July-August 2011

Abstract

In August 2011, Chittoor district authorities reported a cluster of suspected human anthrax cases to the Andhra Pradesh state surveillance unit. We investigated this cluster to confirm its etiology, describe its magnitude, identify potential risk factors, and make recommendations for preventing similar outbreaks in the future. Suspected cutaneous anthrax was defined as a painless skin lesion (papule, vesicle, or eschar) that appeared in a resident of Musalimadugu between July and August 2011. Clinical details and smears from skin lesions from suspected cases were collected to describe the outbreak by time, place and person. A retrospective cohort study among villagers aged ≥ 15 years was conducted to identify risk factors for acquiring the infection. Sixteen livestock in the village died between 24 June and 7 August 2011. Smears from five animals showed Gram-positive, spore bearing characteristics of Bacillus anthracis. Villagers butchered and skinned the dead animals, sold the skin, and consumed the meat after boiling it for two hours. The outbreak in humans started on 30 July, and nine suspected cases of cutaneous anthrax (attack rate: 2%, no deaths) occurred until 7 August. The attack rate was higher among those aged ≥15 years. All the smears were negative on Gram staining. Individuals, who had handled, skinned, and slaughtered dead livestock were at higher risk of infection. We recommend ciprofloxacin prophylaxis to close family contacts. Vaccination of the livestock in the area and community education on the dangers of handling and slaughtering dead/ill livestock are necessary.