CHOLERA

Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. Researchers have estimated that every year, there are roughly 1.4 to 4.3 million cases, and 28 000 to 142 000 deaths per year worldwide due to cholera. The short incubation period of 2 hours to 5 days, is one factor that triggers the potentially explosive pattern of outbreaks.

Symptoms

Cholera is an extremely virulent disease. It affects both children and adults and can kill within hours.
About 80% of people infected with V. cholerae do not develop any symptoms, although the bacteria are present in their faeces for 1-10 days after infection and are shed back into the environment, potentially infecting other people. 

Among people who develop symptoms, 80% have mild or moderate symptoms, while around 20% develop acute watery diarrhoea with severe dehydration. This can lead to death if left untreated. 

Risk factors and disease burden

Cholera transmission is closely linked to inadequate environmental management. Typical at-risk areas include peri-urban slums, where basic infrastructure is not available, as well as camps for internally displaced persons or refugees, where minimum requirements of clean water and sanitation are not met.
The consequences of a humanitarian crisis – such as disruption of water and sanitation systems, or the displacement of populations to inadequate and overcrowded camps – can increase the risk of cholera transmission should the bacteria be present or introduced. Dead bodies have never been reported as the source of epidemics.

Cholera remains a global threat to public health and a key indicator of lack of social development.
The number of cholera cases reported to WHO continues to be high. During 2013, a total of 129 064 cases were notified from 47 countries, including 2102 deaths. The discrepancy between those figures and the estimated burden of the disease is due to the fact that many cases are not recorded for due to limitations in surveillance systems and fear of trade and travel sanctions.

Prevention and control

A multidisciplinary approach is key for reducing cholera outbreaks, controlling cholera in endemic areas and reducing deaths.

Water and sanitation interventions

The long-term solution for cholera control (which benefits all diseases spread by the fecal-oral route) lies in economic development and universal access to safe drinking water and adequate sanitation, which is key in preventing both epidemic and endemic cholera.
Actions targeting environmental conditions include:

• the development of piped water systems with water treatment facilities (chlorination);
• interventions at the household level (water filtration, water chemical or solar disinfection, safe water storage containers); and
• as well as the construction of systems for sewage disposal and latrines.

Most of those interventions require substantial long term investments and high maintenance costs which are difficult to fund and sustain by the least developed countries, where they are also most needed.

Treatment

Cholera is an easily treatable disease. Up to 80% of people can be treated successfully through prompt administration of oral rehydration salts (WHO/UNICEF ORS standard sachet). Very severely dehydrated patients require the administration of intravenous fluids. These patients also need appropriate antibiotics to diminish the duration of diarrhoea, reduce the volume of rehydration fluids needed, and shorten the duration of V. cholerae excretion. Mass administration of antibiotics is not recommended, as it has no effect on the spread of cholera and contributes to increasing antimicrobial resistance.
In order to ensure timely access to treatment, cholera treatment centres (CTCs) should be set up within the affected communities. With proper treatment, the case fatality rate should remain below 1%.

 Social mobilisation
Health education campaigns, adapted to local culture and beliefs, should promote the adoption of appropriate hygiene practices such as hand-washing with soap, safe preparation and storage of food and breastfeeding. 

Awareness campaigns during outbreaks also encourage people with symptoms to seek immediate health care. The campaigns should use modern communication channels (mobile phones, smartphones, social media, etc.) and adapted to local cultures. The use of qualitative methods of analysis, to help adapt messages to local culture and beliefs, is also encouraged.