Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae O1 or O139. It is a global threat to public health and a key indicator of lack of social development.

Recently, the re-emergence of cholera has been noted in parallel with the ever-increasing size of vulnerable populations living in unsanitary conditions.

There are between 21 000 to 143 000 deaths due to cholera every year. Of all deaths caused by cholera, only a small proportion are reported to WHO. While 129 000 to 589 900 cases of cholera have been reported annually to WHO over the past 5 years, it is estimated that between 1.3 and 4.0 million cholera cases occur every year.1

Up to 80% of cases can be successfully treated with oral rehydration solution (ORS. However, very severely dehydrated patients require administration of intravenous fluids. These patients also receive appropriate antibiotics to diminish the duration of diarrhoea, reduce the volume of rehydration fluids needed, and shorten the duration of V. cholerae excretion.

Among people developing cholera, 80% have mild or moderate diarrhoea. Where sanitation facilities are not available bacteria are shed back into the environment, which is a source of further potential infection. About 75% of people infected with Vibrio cholerae O1 or O139 do not develop any symptoms.

Typical at-risk areas of cholera include peri-urban slums with limited access to safe drinking water and a lack of proper sanitation
Risk of cholera is highest in areas where basic infrastructure is not available, as well as in camps for internally displaced population or refugees, where minimum requirements of clean water and sanitation are not met.

Surveillance is paramount to identify vulnerable populations living in hotspots. Surveillance should guide interventions and lead to timely prevention and preparedness activities. When seasonal occurrence can be anticipated, prevention and control must be enhanced prior to the anticipated peak and activities such as preparedness plans, training of healthcare staff, and pre-positioning of supplies must take place.

Safe and effective oral cholera vaccines are now part of the cholera control package. Three types of vaccines are WHO-prequalified. They are licensed in several countries, and the one most commonly used in countries at high risk for cholera has been shown to provide up to 65% protection for up to 5 years in cholera endemic areas. Vaccination should be carried out in conjunction with other proven cholera prevention and control activities such as provision of clean water.

Cholera is a preventable disease provided that safe water and proper sanitation are made available. Cholera control depends on far more than the prompt medical treatment of cases. The interplay of prevention, preparedness and response focusing on water safety and proper sanitation, together with an efficient surveillance system are paramount for mitigating outbreaks and diminishing case fatality rates. Oral cholera vaccine can also play an important part in preventing cholera. .

Once an outbreak is detected it is important to provide rapid access to treatment. The usual intervention strategy in an outbreak is to reduce deaths by ensuring prompt access to adequate treatment. The spread of the disease is also controlled by providing safe water, proper sanitation, and health education for improved hygiene and safe food handling practices. Oral cholera vaccine can also be used to help control the ongoing outbreak and help prevent spread to new areas.

Today, no country requires proof of cholera vaccination as a condition for entry. Past experience shows that quarantine measures and embargoes on the movement of people and goods are unnecessary. Courtesy: WHO

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