Cholera

Cholera is a severe illness caused by Vibrio cholerae bacteria. There are different strains of this bacteria, but only two are known to cause outbreaks. 

Symptoms include sudden watery diarrhoea and vomiting which often leads to dehydration. If left untreated, over half of the people with the most severe cases die within a few hours of the symptoms developing.   

It spreads mainly via the faecal-oral route, through people consuming water or food contaminated with the cholera bacteria from other people’s faeces (poo). Most cases of cholera occur in regions with poor sanitation, water and hygiene. 

Historically, cholera epidemics occurred globally, but in many countries, modern sanitation has largely controlled it.  However, outbreaks still occur in vulnerable regions, particularly in Africa, or during humanitarian crises, where sanitation systems are disrupted, sewage contaminates water supplies, and people are unable to carry out basic hygiene practices. 

As of 1 February 2023, at least 18 countries continue to report cases of cholera, and the World Health Organization (WHO) expects this number to increase due to the ongoing humanitarian crises and a lack of sanitation in some countries. The death rate associated with these outbreaks is worrying, with many countries reporting higher death rates than in previous years. In 2021, the global average cholera death rate was 1.9%, with Africa experiencing a higher rate of 2.9%, the highest in over a decade. 

Preventing cholera is mostly about improving sanitation and hygiene, though vaccines can offer some protection. 

Most people with cholera do not develop any symptoms, but the bacteria can still be found in their poo for up to 10 days after infection. It can then spread back into the environment and potentially infect other people.  

For people who develop symptoms, most only develop mild or moderate symptoms, such as watery diarrhoea. These usually occur between 12 hours and five days of being infected. This can lead to dehydration, and eventually death if left untreated. 

Cholera mainly spreads through contaminated water or food. This can include; 

• Drinking contaminated water 

• Eating food that’s been in contaminated water, e.g. shellfish 

• Eating food that has been washed with contaminated water, e.g. fruit or salad 

• Eating food that has been touched by a person infected with cholera.  

 Apart from following good hygiene practices, such as washing hands with soap after going to the toilet and before eating, for people travelling from the UK to areas where they are advised that cholera is a risk, there is one vaccine available – Dukoral. It is an oral vaccine containing inactivated (killed) cholera toxin and cholera bacteria which is mixed with a buffer (to keep the pH of the vaccine the same as the body) and water. 

In the UK, the cholera vaccine is only given to individuals who are at most at risk of cholera, as the risk to general travellers is relatively low. These people include;  

• Humanitarian or aid workers travelling to an at-risk area 

• Travellers to areas with potential cholera risk 

• People who work in laboratories who may regularly be exposed to cholera as part of their work.  

Globally, two oral cholera vaccines are prequalified by the WHO, meaning that they met the WHO criteria for quality, safety and efficacy of medicinal products – these are Dukoral and Euvichol.  

Euvichol does not require a buffer solution and is available to individuals over one year of age. It is used internationally for mass vaccination campaigns as part of the global oral cholera vaccine stockpile funded by Gavi, the Vaccine Alliance. Over 20 million doses have been used as part of mass campaigns in areas experiencing outbreaks, often during humanitarian crises, or in populations living in areas where the disease is extremely common.  

Cholera can be a constant problem in certain areas (endemic) or can suddenly cause widespread illness (epidemic). If cholera has been found in an area within the last three years and is spreading locally, that area is considered cholera-endemic.  

Cholera outbreaks can happen both in these endemic areas and in places where cholera is not usually found. 

As cholera spreads mainly through contaminated water and poor sanitation, people living in crowded urban slums or refugee camps are especially at risk. During a humanitarian crisis, and water and sanitation systems are disrupted or people are forced into overcrowded camps, the risk of cholera increases.  

In recent years, the number of cholera cases reported to the World Health Organization (WHO) has remained high. In 2022, there were 472,697 reported cases and 2,349 deaths across 44 countries. However, the actual number of cases is likely much higher because many go unreported due to inadequate surveillance systems and concerns about the impact on trade and tourism. 

Source: WHO 

Cholera - the forgotten pandemic