Cholera: prevention and control

The current response to cholera outbreaks tends to be reactive, in the form of an emergency response. While this approach prevents many deaths, it fails to prevent cases of cholera. The importance of medium- and long-term prevention activities in cholera control should therefore be emphasized.

The capacity for disease prevention, epidemic preparedness, and emergency response varies greatly among countries. Regional strategies are needed to ensure that all countries have the capacity to deal with these issues. Among the priorities are:

• the need to obtain better data and ensure greater information sharing;
• the adoption of a coordinated multisectoral approach;
• efforts to improve sanitation and sewage disposal;
• the need to ensure political commitment and community involvement.

Case management

Cholera is a diarrhoeal disease caused by Vibrio cholerae. Children as well as adults can get infected. Among those infected, about 20% develop acute watery diarrhoea, of which 10-20% develop severe watery diarrhoea with vomiting. The mainstay of treatment is rehydration and up to 80% of cholera cases can be treated successfully using only oral rehydration salts.

Prompt and appropriate medical management of cases can significantly decrease mortality; when applied properly, case-fatality rate should be below 1%. In untreated cases the case fatality rate may reach 30-50%. These levels are often observed in crisis situations with overcrowding, limited access to health care, and precarious environmental management.

Surveillance systems

Sensitive surveillance and prompt reporting contribute to the rapid containment of cholera epidemics. In many endemic countries, cholera is a seasonal disease, occurring every year usually during the rainy season. Surveillance systems can provide an early alert to outbreaks, which should lead to a coordinated response, and assist in the preparation of preparedness plans.

As part of an integrated surveillance system, an efficient cholera surveillance system can also improve the risk assessment for potential cholera outbreaks. Understanding the seasonality and location of outbreaks will provide guidance for improving cholera control activities for the most vulnerable. This will also contribute to developing indicators for appropriate use of oral cholera vaccines.

Multisectoral approach

A multisectoral and coordinated approach is paramount in order to efficiently control a cholera outbreak. Key sectors to be involved are health, water and sanitation, fishery and agriculture, and education. A cholera coordination committee should be in place in countries where cholera outbreaks are recurrent. These committees should involve representatives of the different sectors as well as non-governmental organizations and international partners present in the country. Representatives from communication and information also play an important role.

Water supply and sanitation

Cholera is usually transmitted through faecally contaminated water or food. Outbreaks can occur sporadically in any part of the world where water supply, sanitation, food safety, and hygiene are inadequate. WHO recommends improvements in water supply and sanitation as the most sustainable approach for protecting against cholera and other waterborne epidemic diarrhoeal diseases. However, such an approach is unrealistic for the many impoverished populations most affected by cholera.

Personal hygiene, food preparation and health education

Outbreaks can be mitigated and case-fatality rates reduced through several other measures, many of which are suitable for community participation. Human behaviours related to personal hygiene and food preparation contribute greatly to the occurrence and severity of outbreaks.

Health education aimed at behaviour change is thus an important component of cholera prevention and control.

Vaccines

WHO is evaluating the use of newer tools to complement traditionally recommended cholera control measures. Safe and effective oral cholera vaccines are available for use by individuals and health personnel, and work is under way to investigate the role of mass vaccination as a public health strategy for protecting at-risk populations. Issues include logistics, costs, timing, vaccine production capacity, and criteria for the use of mass vaccination to contain as well as prevent outbreaks.