A large cholera outbreak in Kano City, Nigeria: the importance of hand washing with soap and the danger of street-vended water

The aim of this study was to identify the risk factors for cholera during an outbreak in Nigeria. Cases were defined as recent onset of acute diarrhoea with dehydration in a patient hospitalised at the Infectious Diseases Hospital in Kano City. Meningitis patients admitted concurrently at the same hospital were recruited as unmatched controls. Data were collected on age, sex, place of residence, hygienic practices, and on food and water consumption. A total of 5600 cholera cases and 340 cholera deaths were reported between December 1995 and May 1996 (attack rate = 86.3 per 100,000 population) in the state of Kano. Compared to the 77 controls, the 102 cases were more likely to have drunk street-vended water (age-adjusted odds ratio (AAOR) = 3.2; 95% confidence interval (CI): 1.4-7.1) and less likely to have drunk tap water in their homes (AAOR = 0.2; 95% CI: 0.1-0.7) or to have washed hands with soap prior to eating food (AAOR = 0.2; 95% CI: 0.1-0.6). While no data suggested that the municipal water supply was contaminated, safe water systems and hand hygiene practices might have prevented a high proportion of cases if implemented early during this outbreak.