CholeraCholera is an acute diarrhoeal disease usually associated with poverty, poor sanitation and poor access to clean drinking water
Cholera is an acute bacterial disease characterised by profuse watery diarrhoea.
Transmission is mainly by ingestion of contaminated food and water; cholera is considered a disease of poverty and is usually associated with poor sanitation and poor access to clean drinking water.
Globally there are an estimated 1.3 – 4 million cases and an average of 21,000 to 143,000 deaths per year.
Rehydration is the main management for treatment; up to 80 percent of cases can be successfully treated with oral rehydration solution.
The majority of travellers are at low risk of disease: standard food, water and personal hygiene precautions should be observed by all travellers.
An effective vaccine is available for travellers whose activities or medical history puts them at increased risk of disease.
Cholera is an acute diarrhoeal disease caused by ingestion of food or water contaminated with the Gram – negative bacterium Vibrio cholerae . Infection can cause profuse watery diarrhoea which, if left untreated can lead to rapid dehydration. In extreme cases cholera is one of the most rapidly fatal infectious diseases known .
Cholera is endemic in many areas of Asia and Africa. Large epidemics can also occur. Throughout history there have been devastating outbreaks resulting in millions of cases and hundreds of thousands of deaths . Today cholera remains a global threat to public health.
Although more than 200 serogroups of V. cholerae exist, only two cause epidemic disease: serogroup O1 and O139. Serogroup O1 has two biotypes: El Tor and classical, which can be further divided into two serotypes Ogawa and Inaba .
In 2017 a total of 1,227,391 cases of cholera including 5654 deaths were reported to the World Health Organization (WHO) from 34 countries . Cases were reported in 14 countries in Africa 179,835 cases 3220 deaths. The Americas reported a total of 13,818 cases and 163 deaths: the majority of these cases were from Haiti (13,681 cases) .
Nine countries had large outbreaks in 2017; Yemen (over 1 million cases) Democratic Republic of Congo, Ethiopia, Haiti, Nigeria (Borno state), Somalia, South Sudan and Zambia (Lusaka) .
In Asia and Oceania cholera occurs, but case reports are considered incomplete with variable surveillance systems with which to estimate case numbers [4, 6].
Worldwide case numbers are considered to greatly underestimate the actual number of cases for several reasons: under International Health Regulations (2005), notifications of cholera to the WHO are not mandatory , there is often limited capacity for surveillance and laboratory diagnosis, variations occur in case definitions, and fear of negative economic impact on a country which might rely on tourism are thought to reduce reporting of cholera cases .
Risk for travellers
Cholera does not generally occur in high-income countries where there is access to safe drinking water and improved sanitation facilities.
Risk is associated with behaviour. Activities which predispose to infection include drinking untreated water or eating poorly cooked seafood in endemic areas .
Expatriates living in epidemic countries may be at greater risk of cholera . Travellers living or working in less sanitary conditions such as relief workers in disaster or refugee camps are also considered at higher risk .
Cholera in travellers from England, Wales and Northern Ireland
Cholera does not occur in the UK - the last indigenous case reported in England and Wales was in 1893 . However, cases of V. cholerae are occasionally reported in travellers returning from overseas.
In 2018, there were 17 confirmed cases of cholera in travellers. The countries travelled to were Bangladesh(2), India (5), Pakistan(6), Thailand(2), Tunisia(1) and travel details were not known for one traveller (personal communication: Travel and Migrant Health Section, Public Health England, 23 September 2019).
Cholera is mainly transmitted through faecal contamination of food or water. Toxigenic V. cholerae O1 and O139 are free living bacterial organisms found in fresh and brackish (slightly salty) water, often associated with shellfish and aquatic plants. Infection is most commonly acquired from drinking water in which V. cholerae is found naturally or which has become contaminated through infected faeces. Contaminated fish and shellfish are also common routes of transmission.
Cholera transmission is closely linked to inadequate water and sanitation facilities where basic infrastructure is not available. It can also be a major problem affecting those in refugee camps and as a result of natural disasters which disrupt water and sanitation systems .
Humans are the only known host and direct transmission from person to person is uncommon . Large numbers of bacteria are needed to establish infection in those with normal gastric acidity .
V. cholerae is excreted in the stool of a infected person. Asymptomatic patients (those without symptoms) infected with V. cholerae O1 or O139 can shed the organism for a few days or up to 2 weeks in patients with symptoms.
Signs and symptoms
Cholera can be mild or occur without symptoms in healthy individuals. Cholera is characterised by sudden onset of profuse, watery diarrhoea (‘rice-water’ stools) with occasional vomiting . The incubation period is usually 2 – 5 days but may be as short as a few hours. Dehydration and electrolyte abnormalities are the most common complications of disease, with 5 – 10 percent of those infected having severe disease leading to metabolic acidosis and circulatory collapse.
Blood group O and hypochlorhydria (reduced stomach acid) is known to be associated with increased risk of severe cholera .
Diagnosis and treatment
In extreme cases cholera is one of the most rapidly fatal infectious diseases known . However, cholera can be easily treated through prompt administration of oral rehydration solution.
Severely dehydrated patients may require rapid administration of intravenous fluids, plus oral rehydration solution . Antibiotics may be used in epidemic situations to reduce the volume of diarrhoea and duration of symptoms. Left untreated, over 50 percent of the most severe cases may die; however with prompt treatment, mortality is less than 1 percent. Mild cases with moderate diarrhoea also occur and asymptomatic infection is common .
Health professionals should be alert to the possibility of cholera in those who have returned from endemic areas. Cholera is a notifiable disease in England, Wales and Northern Ireland and Health professionals must inform local health protection teams or equivalents of suspected cases.
Primary diagnostic tests are performed at local hospital laboratories by examining faecal specimens from cases reporting gastrointestinal symptoms and travel to regions of the world where cholera is endemic. Faecal specimens are cultured on selective media. Colonies of V. cholerae typically appear as large, yellow colonies and can be speciated at the local laboratories using biochemical tests. Suspect colonies should be sent for further testing (with full clinical and travel history) to Public Health England’s Gastrointestinal Bacteria Reference Unit (GBRU). At GBRU, isolates are biochemically confirmed as V. cholerae, serotyped, biotyped and molecular tests are used to identify the presence of cholera toxin. Isolates are archived for batch testing for the detection of antimicrobial resistance for surveillance purposes.
For the majority of travellers, the risk of acquiring cholera can be reduced by following advice on food and water hygiene and by ensuring good personal hygiene.
An oral cholera vaccine (Dukoral) has been available in the UK since May 2004, although immunisation is not indicated for the majority of travellers.
An oral, inactivated cholera vaccine, Dukoral, is licensed in the UK for protection against infection caused by V. cholerae serogroup 01.
The Summary of Product Characteristics (SPC) for this vaccine, available via the electronic Medicines Compendium, should be consulted for specific information relating to the product, and before administration of any vaccine.
Indications for use of vaccine
Cholera is considered to represent a potential risk to travellers if:
- a country had reported ≥100 cases to the WHO in at least 3 out of 5 years, 2013 to 2017 inclusive
- a country had reported an outbreak of ≥1000 cases to the WHO in at least one year, 2013 to 2017 inclusive
When there had been sporadic or absent reporting to WHO between 2013 and 2017, a consensus opinion was formed based on consideration of available data, and World Health Organization progress on household drinking water, sanitation and hygiene 2000-2017.
All travellers should take care with personal, food and water hygiene. The vaccine is not indicated for most travellers, but can be recommended for those whose activities or medical history puts them at increased risk. This includes:
- aid workers
- those going to areas of cholera outbreaks who have limited access to safe water and medical care
- those for whom vaccination is considered potentially beneficial
Since 1973 when WHO removed cholera vaccination from the International Health Regulations, countries no longer require proof of cholera vaccination from travellers as a condition of entry. Experience has shown that restricting the movement of people (and goods) is not effective in controlling the spread of cholera and is therefore unnecessary .
Immunisation against cholera falls under Additional Services under the General Medical Services (GMS) and Personal Medical Services (PMS). Patients registered for NHS services should not be charged for cholera vaccine. This is assuming the individual is travelling to an area where there is a risk of exposure to infection as a consequence of being in that area .
Cholera vaccine and prevention against travellers’ diarrhoea
Oral cholera vaccine may also provide some protection against diarrhoea caused by the heat-labile toxin of Escherichia coli (E. coli). Although licensed for protection against travellers’ diarrhoea in a number of countries, it is not licensed (nor recommended) for this indication in the UK. Studies demonstrating the efficacy of cholera vaccine in preventing travellers’ diarrhoea are limited, and the prevalence of heat-labile toxin-producing E. coli is only considered to account for a small proportion of all cases of travellers’ diarrhoea [9, 12].
See our factsheet on travellers’ diarrhoea for more information.
Vaccine schedule (Dukoral)
|Age range||Schedule||Duration of protection|
|Adults and children from 6 years||Two doses with an interval of at least 1 week but less than 6 weeks between them*||2 years|
|Age 2 to below 6 years||Three doses with an interval of at least 1 week but less than 6 weeks between them*||6 months|
*If more than 6 weeks have elapsed between doses the primary course should be restarted [9, 13].
If more than 2 years (or 6 months for children aged 2 to below 6 years of age) has elapsed since the last dose of vaccine, the primary course should be repeated .
Dukoral has been given to children between 1 and 2 years of age in immunogenicity and safety studies. However, protective efficacy has not been studied in this age group. Therefore Dukoral is not recommended for children under 2 years of age .
Dukoral is for oral administration: food and drink should be avoided for 1 hour before and 1 hour after vaccination. Oral administration of other medicinal products should also be avoided within 1 hour before and 1 hour after administration of Dukoral .
Immunisation should be completed at least 1 week prior to potential exposure to V. cholerae.
Efficacy of vaccine
The true efficacy of the vaccine in preventing cholera in travellers is not known as risk in this population is too low to be able to carry out efficacy trials. However, oral cholera vaccine has demonstrated a protective efficacy of between 61 – 86 percent against V cholerae 01 for 4 – 6 months in those living in endemic countries. In children under 6 years of age, protection wanes rapidly after 6 months . The vaccine does not provide protection against V cholerae 0139.
There are few individuals who would be unable to receive the oral cholera vaccine when indicated.
The vaccine should not be given to those who have had:
- confirmed anaphylactic reaction to a previous dose of oral cholera vaccine
- confirmed anaphylactic reaction to formaldehyde or any of the components of the vaccine
The most commonly reported adverse events have been mild gastro-intestinal symptoms (abdominal pain, cramping, diarrhoea, nausea). Serious adverse events, including a flu-like syndrome, rash and arthralgia are rare .
First Published : 03 Oct 2019
Last Updated :  03 Oct 2019
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