Let’s talk about cholera

If we can fix our water system, improve environmental sanitation and personal hygiene, we should be able to curtail Cholera. It is an acute intestinal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. It has a short incubation period, from less than one day to five days, and produces […]

If we can fix our water system, improve environmental sanitation and personal hygiene, we should be able to curtail Cholera. It is an acute intestinal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. It has a short incubation period, from less than one day to five days, and produces an enterotoxin that causes a copious, painless, watery diarrhoea that can quickly lead to severe dehydration and death if treatment is not promptly given.
According to World Health Organisation (WHO) there are an estimated 3-5 million cholera cases and 100 000-120 000 deaths due to cholera every year. Up to 80% of cases can be successfully treated with oral rehydration salts. Effective control measures rely on prevention, preparedness and response. Provision of safe water and sanitation is critical in reducing the impact of cholera and other waterborne diseases. Cholera is an extremely virulent disease. It affects both children and adults and can kill within hours.
About 75% of people infected with V. cholerae do not develop any symptoms, although the bacteria are present in their faeces for 7-14 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 untreated. People with low immunity – such as malnourished children or people living with HIV – are at a greater risk of death if infected.
As reported by WHO, 2 serogroups of V. cholerae – O1 and O139 – cause outbreaks. V. cholerae O1 causes the majority of outbreaks, while O139 – first identified in Bangladesh in 1992 – is confined to South-East Asia.Non-O1 and non-O139 V. cholerae can cause mild diarrhoea but do not generate epidemics.The main reservoirs of V. cholerae are people and aquatic sources such as brackish water and estuaries, often associated with algal blooms. Recent studies indicate that global warming creates a favourable environment for the bacteria.

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 people or refugees, where minimum requirements of clean water and sanitation are not met. The consequences of a disaster – 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. Epidemics have never arisen from dead bodies. Cholera remains 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.

Prevention and control.
A multidisciplinary approach based on prevention, preparedness and response, along with an efficient surveillance system, is key for mitigating cholera outbreaks, controlling cholera in endemic areas and reducing deaths. 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 administration of intravenous fluids. Such patients also require appropriate antibiotics to diminish the duration of diarrhoea, reduce the volume of rehydration fluids needed, and shorten the duration of V. cholerae excretion. In order to ensure timely access to treatment, cholera treatment centres (CTCs) should be set up among the affected populations. With proper treatment, the case fatality rate should remain below 1%.
Once an outbreak is detected, the usual intervention strategy is to reduce deaths by ensuring prompt access to treatment, and to control the spread of the disease by providing safe water, proper sanitation and health education for improved hygiene and safe food handling practices by the community. The provision of safe water and sanitation is a formidable challenge but remains the critical factor in reducing the impact of cholera.

Oral cholera vaccines.
There are two types of safe and effective oral cholera vaccines currently available on the market. Both are whole-cell killed vaccines, one with a recombinant B-sub unit, the other without. Both have sustained protection of over 50% lasting for two years in endemic settings.
Both vaccines are WHO-prequalified and licensed in over 60 countries. Dukoral has been shown to provide short-term protection of 85-90% against V. cholerae O1 among all age groups at 4-6 months following immunization. The other vaccine (Shanchol) provides longer-term protection against V. cholerae O1 and O139 in children under five years of age. Both vaccines are administered in two doses given between seven days and six weeks apart.
WHO recommends that immunization with currently available cholera vaccines be used in conjunction with the usually recommended control measures in areas where cholera is endemic as well as in areas at risk of outbreaks. Vaccines provide a short term effect while longer term activities like improving water and sanitation are put in place.
Let us remain vigilant, report any suspected case, continue to raise awareness through health education, media campaign and engage our leaders to allocate funds for Cholera vaccine, improve water system and environmental sanitation.
All comments to Dr Aminu Magashi at [email protected]