Cholera

About Cholera

Cholera is an acute intestinal infection caused by the bacterial Vibrio cholerae (V. cholerae). The main mode of infection is through contaminated food and drinking water. The spread of the disease within an area can be prevented through early detection and confirmation of cases, followed by appropriate response. Because cholera can be an acute public health problem a well-coordinated, timely, and effective response to outbreaks is paramount. An epidemic of cholera can be more quickly controlled when the public understands how to help to limit the spread. Health education is crucial to ensure the participation of the community. Best practices of risk communication are thus crucial in addressing cholera epidemics.

Nature of the illness

Cholera is a diarrhoeal disease caused by infection of the intestine with the bacterium Vibrio cholerae, either type O1 or O139. With type O1 causing the majority of outbreaks worldwide. V. cholerae produces several toxins, but the classical dehydrating diarrhoeal symptoms of cholera are caused by the cholera enterotoxin. Cholera is usually transmitted through faecal contaminated water or food and remains an ever-present risk in many countries. New outbreaks can occur sporadically in any part of the world where water supply, sanitation, food safety, and hygiene are inadequate. The greatest risk occurs in over-populated communities and refugee settings characterized by poor sanitation, unsafe drinking-water, and increased person-to-person transmission.

Who is affected

All humans- both children and adults can be infected but the most vulnerable persons who lacked access to safe water and food supply and sanitation facilities, children less than 5 years, and pregnant women. About 20% of those who are infected develop acute, watery diarrhoea – 10–20% of these individuals develop severe watery diarrhoea with vomiting. If these patients are not promptly and adequately treated, the loss of such large amounts of fluid and salts can lead to severe dehydration and death within hours. The number of cases can rise extremely quickly due to the very short incubation period (2 hours to 5 days).

Historical background and other contexts

The Ganges Delta region is believed to be the traditional home of cholera. From this region, cholera has spread throughout the world, causing seven major pandemics since 1817. The seventh pandemic, which began in 1961 in Indonesia, reached West Africa in 1970. In Ghana the first bacteriological case report of cholera was on 1st September, 1970. Since then, cholera has been endemic in Ghana, with occasional outbreaks. From 1999 to 2005, the Ghana Ministry of Health officially reported a total of 26,924 cases and 620 deaths to the World Health Organization (WHO). Since the past three decades, the worst cholera epidemic in Ghana occurred in 2014 where 17,000 people were affected with over 150 deaths. Cholera outbreaks continue to be a major public health problem in Ghana and Africa as a whole. For example, by the end of June 2012, cholera had killed nearly 200 people in West Africa and infected 10,330 people (UNICEF). According to WHO, between January and April 2012, a total of 25 856 cases and 538 deaths were reported from 20 countries resulting in a CFR of 2.1%. DR Congo, Ghana, Uganda and Sierra Leone accounted for 84% of the total number of cases and 73% of all deaths.

Levels of risk and level of exposure

In Ghana and many African countries lack of safe water supplies, poor sanitation, poor hygienic practices, general lack of food safety infrastructure and increasing consumption of out-of-home meals often prepared and sold under unhygienic conditions increase the risks and exposure levels of people to cholera outbreaks.

Common sources of cholera infection include:

• Drinking-water that has been contaminated
• Ice made from contaminated water.
• Cooking utensils washed in contaminated water.
• Food contaminated during or after preparation.
• Seafood, particularly crustaceans and other shellfish, taken from contaminated water and eaten raw or insufficiently cooked or contaminated during preparation.
• Fruit and vegetables grown at or near ground level and fertilized with night soil, irrigated with water containing human waste, or “freshened” with contaminated water, and then eaten raw, or contaminated during washing and preparation.

Ability to control the risk

It is known that improvements in water supply, sanitation, food safety and community awareness of preventive measures are the best means of preventing cholera. Over the years, a number of interventions have been implemented in many parts of Ghana however unsafe water supplies, sanitation and poor food safety practices still remain a challenge. Oral cholera vaccines are also being used. To mitigate the spread of the infection, especially among children, the Ghana Government introduced the pneumococcal and rotavirus vaccines to reduce infant diarrhoea. This intervention contributed significantly to the reduction of diarrhoea cases among infants.

Treatment

Cholera is an easily treatable disease. The majority of people can be treated successfully through prompt administration of oral rehydration solution (ORS). The WHO/UNICEF ORS standard sachet is dissolved in 1 litre (L) of clean water. Adult patients may require up to 6 L of ORS to treat moderate dehydration on the first day. Severely dehydrated patients are at risk of shock and require the rapid administration of intravenous fluids. These patients are also given appropriate antibiotics to diminish the duration of diarrhoea, reduce the volume of rehydration fluids needed, and shorten the amount and duration of V. cholerae excretion in their stool.

Mass administration of antibiotics is not recommended, as it has no proven effect on the spread of cholera may contribute to antimicrobial resistance.

Rapid access to treatment is essential during a cholera outbreak. Oral rehydration should be available in communities, in addition to larger treatment centres that can provide intravenous fluids and 24-hour care. With early and proper treatment, the case fatality rate should remain below 1%.

Zinc is an important adjunctive therapy for children under 5, which also reduces the duration of diarrhoea and may prevent future episodes of other causes of acute watery diarrhoea.