Between 23 August and 15 December 1990 an epidemic of cholera affected Mozambican refugees in Malawi causing 1931 cases (attack rate = 2.4%); 86% of patients had arrived in Malawi < 3 months before illness onset. There were 68 deaths (case-fatality rate = 3.5%); most deaths (63%) occurred within 24 h of hospital admission which may have indicated delayed presentation to health facilities and inadequate early rehydration. Mortality was higher in children < 4 years old and febrile deaths may have been associated with prolonged i.v. use. Significant risk factors for illness (P < 0.05) in two case-control studies included drinking river water (odds ratio [OR] = 3.0); placing hands into stored household drinking water (OR = 6.0); and among those without adequate firewood to reheat food, eating leftover cooked peas (OR = 8.0). Toxigenic V. cholerae O1, serotype Inaba, was isolated from patients and stored household water. The rapidity with which newly arrived refugees became infected precluded effective use of a cholera vaccine to prevent cases unless vaccination had occurred immediately upon camp arrival. Improved access to treatment and care of paediatric patients, and increased use of oral rehydration therapy, could decrease mortality. Preventing future cholera outbreaks in Africa will depend on interrupting both waterborne and foodborne transmission of this pathogen.
PIP: An epidemiologic investigation of a 1990 cholera outbreak among Mozambican refugees in the Nyamithuthu camp in Malawi highlighted the challenges of providing adequate treatment and prevention in this setting. Between August 23 and December 15, 1990, 1931 cholera patients were admitted to the camp's intravenous (IV) treatment tent (attack rate, 2.4%); 28% were under 6 years of age. There were 68 deaths among these patients, for a case-fatality rate of 3.5%. 84% of patients for whom data were available had come to Malawi less than 3 months before the onset of illness and 52% were admitted for treatment within 16 days of camp arrival. 60% of the 40 cholera deaths investigated in detail involved children under 4 years of age (17% of total cases). Acute dehydration was the most common cause of death among the 63% who died within 24 hours of IV tent admission, suggesting delayed presentation and inadequate early rehydration. The remaining patients died from complications (e.g., infections with fever caused by prolonged IV use). In 2 case-control studies, cholera was significantly associated with placing hands into the storage container holding household drinking water (odds ratio, 6.0), obtaining drinking water from the river (odds ratio, 3.0), and eating leftover unheated cooked peas (odds ratio, 8.0). Toxigenic Vibrio cholerae O1, serotype Inaba, was isolated from patients and stored household water. Increased water rations and running water during cholera outbreaks are recommended to reduce contamination of stored drinking water during washing. More rapid referral to IV tents, administration of oral rehydration solution in addition to IV, quick removal or replacement of IV lines to prevent infection, and more attention to child cases also would reduce cholera mortality.