Investigation of a Cholera Outbreak in Ethiopia's Oromiya Region

Abstract

Objectives: In late June 2006, Ethiopia's Oromiya Region was affected by an outbreak of acute watery diarrhea, subsequently confirmed to be caused by Vibrio cholerae O1, a pathogen not known to be endemic to this area. Despite initial control efforts, the outbreak quickly spread to neighboring zones and regions. The Oromiya Health Bureau required public health assistance to investigate the outbreak, determine potential causes, and assess the adequacy of the response, particularly given the concern that the number of cases being reported by health care personnel might represent only a fraction of what actually existed in the community.

Methods: A physician-epidemiologist–led team assessed the Guji, Bale, and East Shewa zones from September 15 to October 9, 2006. By using a purposive sample, we surveyed health bureau staff and cholera treatment center (CTC) staff and community members, assessed CTC sites, and interviewed key personnel of the various organizations responding to the outbreak.

Results: The cholera cases mapped along the Ganale River. The individual attack rates were low (ranging from ~ 0.03% to ~ 4.12%), as was the overall attack rate for all 3 zones (almost 0.50%). The individual CTC case fatality rates ranged from 0% to 6.4%, and the overall case fatality rate was 1.11%. There was a trend toward men being disproportionately affected. This outbreak resulted primarily from poor sanitation and insufficient access to clean water. In Oromiya, the outbreak was addressed by a prompt and effective response, which included village chairmen at the community level. The use of community-based workers was successful and likely contributed significantly to control of the outbreak.

Conclusion: Future epidemics will undoubtedly occur unless basic water and sanitation deficiencies are properly addressed. This outbreak prompts the need for increased local public health capacity to apply prevention strategies and establish ongoing surveillance. Signatories to the World Health Organization International Health Regulations must report outbreaks of nonendemic diseases.

(Disaster Med Public Health Preparedness. 2010;4:312-317)