There have recently been reports of a small number of deaths and a larger number of cases of diarrhoea (with and without vomiting) in the province of Cabo Delgado. This outbreak has been attributed to the consumption of fish contaminated with pesticides, but little scientific data are available to substantiate these claims. Concurrently, there are outbreaks of both cholera and dysentery in the country and local health services have difficulty differentiating between symptoms of chemical poisoning and illness caused by microbial pathogens. Approximately 100 deaths have occurred and about 600 cases of illness have been reported by the provincial health authorities, but attributing these to either chemical or microbiological contamination of food or water consumed is not possible because of lack of reliable scientific data.