Recurrent cholera epidemics in Kano--northern Nigeria.

Objectives: The study examined the factors associated with recurrent cholera epidemics in Kano State of Northern Nigeria, the management of the epidemics and health outcomes.

Methods: Using epidemiological data from the Public Health Department of the Kano State Ministry of Health, the study examined the frequency and geographical distribution of the epidemics for the period 1995 to 2001; procedures for detection; control measures as well as results of biological and bacteriological testing of water from different sources. Mapping and testing for significance of faecal contamination of water sources were done.

Results: The number of cholera cases in the city was 2 630; 847 and 2 347 in 1995/6, 1997 and 1999 respectively. The State Epidemiological Unit which is responsible for surveillance detected epidemics using set thresholds and activated multi-sectoral emergency responses. Control measures encompassed accurate diagnosis at the reference laboratory, Kaduna; registration of cases; case management and public health measures targeting personal hygiene and water treatment. The cholera epidemics attracted worldwide attention with emergency responses from many agencies including WHO, UNICEF and Medicens Sand Frontiers (MSF). Case fatality rates decreased from 15% in 1995/6 to 5% in 1997 and 2% in 1999. The organism responsible for all the outbreaks was Vibrio cholerae, el-tor of inaba serotype. Water contamination of all sources was the principal cause of the epidemics. There were statistically significant differences in levels of faecal contamination of water sources, wells being most affected, followed by piped water, chi2 = 11.556, (p < 0.02). Bore holes were relatively safer sources of water. Point source epidemics always started from Kano City before fanning out to the rest of the State.

Conclusion: Multi-sectoral Epidemic Preparedness and Response (EPR) approaches have contributed to the reduction in case fatality rates over the years and should be sustained. However, in order to prevent future cholera epidemics, there is need to introduce intervention measures that address the root problems of poor sanitation and unsafe water supplies.