Cholera is an acute diarrhoeal disease caused by infection of the intestine with the bacterium Vibrio cholerae, either type O1 or type O139. Both children and adults can be infected.
About 20% of those who are infected with V. cholerae develop acute watery diarrhoea; approximately 20% of these individuals develop severe watery diarrhoea, many also with vomiting. If these patients are not promptly and adequately treated, the loss of fluid and salts can lead to severe dehydration and death within hours. The case fatality rate in untreated cases may be 30–50%. However, treatment is straightforward (rehydration) and, if provided rapidly and appropriately, the case fatality rate should remain below 1%.
Cholera is transmitted by ingestion of faecally contaminated water or food and remains an ever-present risk in many countries. New outbreaks can occur in any part of the world where water supply, sanitation, food safety and hygiene are inadequate. The risk of cholera is considerably increased in humanitarian emergencies, when there are significant population movements and crowding in sites where displaced persons gather and frequent disruption of, or inadequate, access to healthcare services, clean water, sanitation and hygiene. Because the incubation period of cholera is short (2 hours to 5 days), the number of cases can rise quickly and many deaths can occur, creating an acute public health problem.
Spread of the disease within an area can be reduced through early detection and confirmation of cases, followed by an appropriate, well-coordinated multisectoral response. A strong multisectoral cholera preparedness plan that is well implemented will contribute to a more effective outbreak response.
In the long term, improvements in water supply, sanitation, food safety and community awareness of preventive measures are the best means of preventing cholera and other diarrhoeal diseases. In addition, WHO recommends that oral cholera vaccine use should be systematically considered as one of the measures to contribute to controlling cholera during outbreaks, in endemic areas and in humanitarian crises where there is a high risk of cholera.