Shigellosis outbreak at Addis Ababa University: March-April 2010.

BACKGROUND: Between 2006 and 2008, there have been various reports of diarrhea with blood in Ethiopia and also reports of Shigelloses outbreaks in some parts of the country. In March 2010, Addis Ababa University (AAU) Technology Campus reported occurrence of an outbreak of diarrheal illness among students. OBJECTIVE: The study was conducted to identify the causative agent and the possible source of the diarrhea outbreak that occurred at Technology Campus. MATERIALS AND METHODS: Active case finding and review of medical records were undertaken to characterize the outbreak. The investigation consisted of a case-control study with laboratory testing and environmental assessment. A structured questionnaire was used to collect data. Data were analyzed using Epi-info (v3.3.2). RESULTS: A total of 104 suspected cases were identified, based on the case definition, with an attack rate of 6.8%. Stool culture confirmed Shigella flexneri species in 5/11 (45%) of specimens tested. Risk factors associated with illness included eating specific foods at specific meal times. Food items served on Friday March 26, at lunch time (OR: 3.59, CI: 1.0- 12.7, p = 0.04) and on Saturday March 27, during dinner (OR: 2.89 CI: 1.0- 8.2, p = 0.04) were significantly associated with increased odds of illness. Water stored in a tank in the cafeteria had evidence of fecal contamination (fecal coliform count > 161 Mpn /100ml) and the hygiene and sanitary conditions in the cafeteria, kitchen, living area were unsatisfactory. CONCLUSION: Food-borne transmission and water contamination were suspected as the sources of infection. Regular supervision and inspection of the campus' food handling facilities and practices were recommended to improve food hygiene and sanitation. Improved water storage, correcting periodic water shortages in the latrine facility and promotion of hand washing could reduce potential future outbreaks.