Cholera in Africa: lessons on transmission and control for Latin America

Abstract

In January, 1991, epidemic cholera emerged in Peru and spread to 7 other countries of Latin America. Cholera was introduced 20 years ago to Africa, where it spread rapidly to 30 of the 46 countries of the region and by 1990 accounted for 90% of all cases reported to the World Health Organisation. Many lessons from the cholera epidemic in Africa are relevant to efforts to control the disease in Latin America. Public health practices from the past--quarantine and cordon sanitaire to halt introduction of cholera by travellers, and vaccination and mass chemoprophylaxis to control epidemics--are ineffective in preventing spread of the disease. Cholera can be transmitted not only by contaminated water but also by food. Social phenomena such as mass migrations and burial practices may play a greater role than previously understood. While efforts to prevent the spread of cholera have been ineffective, cholera-associated mortality can be decreased with rehydration therapy. Since the current pandemic is unlikely to retreat soon, new strategies are urgently needed to control the spread of cholera through sanitary and behavioural interventions or improved vaccines.

PIP: Latin America had been free of cholera for 70 years until January 1991 when the 7th pandemic of El Tor cholera struck Peru. It killed 1500 people and affected 200,000 people within 6 months. It soon spread to at least 7 other Latin American countries. 20 years earlier the it reached Africa. Foci of infections in Africa included markets, fairs, funerals, and refugee camps. Scientists doubted that vaccination or quarantine would have prevented its introduction into Africa. Yet, in Latin America, public health officials should earnestly reconsider chemoprophylaxis (tetracycline) of family contacts in families with high rates of illness. Presently no such data exist in Latin America. In addition, health workers should test the new oral vaccine in Latin America since there is no preexisting immunity and the people are exposed to high levels of contamination. Little epidemic research was done in Africa to pinpoint modes of transmission so health workers could learn what types of intervention were warranted. It should be done in Latin America, however. As for quarantine, symptomatic and mild to moderate cholera cases can outnumber severe cases as much as 100 to 1, so confining cases would not prevent the spread of the disease. Latin America should broaden diarrheal disease control programs to include adults so they will accept oral rehydration therapy (ORT). It should be used in mild to moderate dehydration cases and intravenous rehydration therapy for severe cases. If the environmental factors are not known and understood and if feces contaminate water supplies, foods, and fisheries, cholera may become endemic in Latin America. In conclusion prompt disease reporting, surveillance, and implementation of control measures could prevent the endemicity of cholera in Latin America.