An investigation of an anthrax outbreak in Makoni District, Zimbabwe

Abstract

Background: In Zimbabwe, anthrax continues to be a disease of public health importance with sporadic outbreaks reported in many parts of the country annually. A human anthrax outbreak occurred in Makoni District Ward 22 and 23 between June 2013 and February 2014. The human anthrax outbreak followed cattle deaths in the wards, which were laboratory confirmed to be due to anthrax. We report the clinical characteristics, distribution of anthrax cases (places, person and time), risk factors for contracting the disease, environmental assessment, district preparedness and response and outbreak prevention and control measures. Methods: We conducted an outbreak investigation with the design of a 1:1 case-control study. Cases and controls were frequency matched against sex. Data were collected using a structured interviewer-administered questionnaire. Environmental assessment, district preparedness and response and outbreak prevention and control measures were assessed using a checklist, observations and key informant interviews. Multivariable unconditional logic regression analysis was performed to identify independent risk factors associated with contracting anthrax. Results: Of the 64 cases, 37 cases and 37 controls were interviewed. All the cases had cutaneous anthrax with the commonest site of eschar being the hand (43%). Most of the cases (89%) were managed according to the national guidelines. On multivariable analysis, source of meat from other villagers [vs butchery, OR = 15.21, 95% CI (2.32-99.81)], skinning [OR = 4.32, 95% CI (1.25-14.94)] and belonging to a religion which permits eating meat from cattle slaughtered due to unknown illness or butchered after an unobserved death [OR = 6.12, 95% CI (1.28-29.37)] were associated with contracting anthrax. The district was poorly resourced and delayed to respond to the outbreak. Conclusion: The described anthrax outbreak resulted from contact and consumption of infected cattle meat. The district office response was delayed and was not prepared to control the outbreak. However, the outbreak was eventually controlled through cattle vaccination; health education and awareness campaigns. The district should strengthen its emergency preparedness and response capacity, revive zoonotic committees, conduct awareness campaign during the high-risk period and improve the surveillance of anthrax during high-risk periods.