An outbreak of liver disease in Tahtay Koraro Woreda, Tigray region of Ethiopia: a case-control study for the identification of the etiologic agent.

BACKGROUND: An outbreak of fatal liver disease of unidentified origin in Tahtay Koraro Woreda, Tigray Region was reported at the end of 2005. In response to this report, a team of investigators was deployed from the EHNRI to assess the situation in the affected area. OBJECTIVES: The objective of the trip was to investigate the probable etiological agent(s) for the stated health problem and to suggest possible means of containing the outbreak. METHOD: A case-control epidemiological method was employed in collecting information from the affected (case) area and a non-affected adjacent area (control) using structured questionnaire. Qualitative data was also collected through focus group discussion (FGD) at community as well as woreda level. Samples of biological and environmental nature were also collected from both case and control areas for a subsequent laboratory analysis in order to identify the causative agent of the outbreak. RESULT: The comparative analysis of the various variables and possible exposure factors between the two sites (case vs control village) revealed that both villages were similar in terms of their exposure to most of the suspected factors including exposure to chemicals, food storage and handling practices, and to the use of traditional herbal medicines or consumption of wild edible plants. However, it was observed that the residents in the affected site (over 96%) relied more on unprotected or protected well as a source of drinking water and other household purposes while most in the non-affected depended on fresh water from river or unprotected spring. This difference was significant, p = 0.000 (OR = 840, 95% CI = 50.1, 14095.7). CONCLUSION: Though several of the possible exposure factors to the epidemic appear to be similar for both the case and control villages, the water source they use for drinking and other household purposes differed markedly. It therefore seems plausible that the problem in the case area could be linked to this water source.