Cholera

Cholera is an acute diarrhoeal disease usually associated with poverty, poor sanitation and poor access to clean drinking water Cholera

 

Key Messages

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 95,000 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.

Overview

Cholera is an acute diarrhoeal disease caused by ingestion of food or water contaminated with the Gram – negative bacterium Vibrio cholerae [1]. 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 [2].

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 [2]. 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 [3].

Cholera has existed in the Indian subcontinent for centuries, but since 1817, seven cholera epidemics have spread from Asia to much of the world [4]. The El Tor biotype is responsible for the current pandemic which began in 1961 in Sulawesi, Indonesia, and spread west reaching South America by 1991 [3, 5]. In 1992 a large outbreak occurred in Bangladesh and India from which a new serogroup O139 was isolated, and which has now spread to at least 11 other countries [3].

Risk areas

In 2015 a total of 172,454 cases of cholera including 1,304 deaths were reported to the World Health Organization (WHO) from 42 countries [6]. Cases were reported from 16 countries in Africa, 13 in Asia, 6 in Europe, 6 in the Americas and 1 in Oceania. Five countries accounted for 80 percent of all cases reported: Afghanistan, Democratic Republic of the Congo (DRC), Haiti, Kenya and Tanzania. These figures are however, 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 [6], 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 [4].

A recent study estimated that 1.3 – 4 million cases and 95,000 deaths occurred annually worldwide between 2008 and 2012, with Sub-Saharan Africa accounting for the majority (60%) of the burden of disease, followed by South-East Asia with 29% of cases [4].

Countries or areas which have reported outbreaks of cholera between 2010 and 2014 can be seen on the WHO map below. However, it is important to note that risk areas can change and country specific information and recommendations should be referred to on our Country Information pages and on the Outbreak Surveillance section.

Source: WHO, 2015

Risk for travellers

Cholera does not generally occur in high-income countries where there is access to safe drinking water and improved sanitation facilities.

The risk of cholera for those travelling to endemic areas is not easy to determine. Data on cases imported into Europe and North America suggest an estimated risk of 2 – 3 cases per million travellers [7-10].

In healthy travellers, infection is often self-limiting and may not be severe. Cases may also be treated without microbiological diagnosis. Therefore although cases in travellers may occur, they can remain unrecognised [10].

Risk is associated with behaviour. Activities which predispose to infection include drinking untreated water or eating poorly cooked seafood in endemic areas [7].

Expatriates living in epidemic countries may be at greater risk of cholera [3], and one study estimated an incidence of 5.3 cases per 1,000 population per year of exposure [8, 11]. Travellers living or working in less sanitary conditions such as relief workers in disaster or refugee camps are also considered at higher risk [10].

Cholera in travellers from England and Wales

Cholera does not occur in the UK - the last indigenous case reported in England and Wales was in 1893 [12]. However, cases of V. cholerae are occasionally reported in travellers returning from overseas.

Between 2004 and 2013 an average of 15 cases of cholera caused by toxigenic V. cholerae serogroups O1 and O139 were reported in England and Wales each year [13]. Out of a total of 147 reported cases, 113 (77 percent) were presumed to have acquired their infection in the Indian sub-continent (personal communication: Travel and Migrant Health Section, Public Health England, 28 April 2017). Data from cases imported into England, Wales and Northern Ireland between 1990 and 2003 suggested an estimated risk of cholera in UK travellers to the Indian subcontinent to be 1 case per 100,000 travellers [3].

Data source: Gastrointestinal Infectious Reference Unit, PHE, Colindale. Data collated by the Travel and Migrant Health Section

Transmission

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 [6].

Humans are the only known natural host and direct transmission from person to person is uncommon [2]. Large numbers of bacteria are needed to establish infection in those with normal gastric acidity [3].

Asymptomatic patients (those without symptoms) infected with V. cholerae O1 or O139 can shed the organism for a few days. Patients who are symptomatic shed the organism from between 2 days and 2 weeks [5]. 

Signs and symptoms

Cholera is characterised by sudden onset of profuse, watery diarrhoea (‘rice-water’ stools) with occasional vomiting [12]. 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 is known to be associated with increased risk of severe cholera [2].

Diagnosis and treatment

In extreme cases cholera is one of the most rapidly fatal infectious diseases known [2]. 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 [5]. Antibiotics may also be given to reduce the volume of diarrhoea and duration of excretion of V. cholerae. 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 [12].

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.

Preventing cholera

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.

Vaccine information

Availability

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

Country specific information on the risk of cholera can be found on our Country Information pages and Outbreak Surveillance section.

Country specific recommendations for the use of cholera vaccine in travellers can be found on our Country Information pages.

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, 2010 to 2014 inclusive
  • a country had reported an outbreak of ≥1000 cases to the WHO in at least one year, 2010 to 2014 inclusive

When there had been sporadic or absent reporting to WHO between 2010 and 2014, a consensus opinion was formed based on consideration of available data, and whether the country borders a country endemic for cholera.

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 [6].

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 [14].

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 [12].

See our factsheet on travellers’ diarrhoea for more information.

Vaccine schedule (Dukoral)

Age RangeScheduleDuration of Protection
Adults and children older than 6 years Two doses with an interval of at least one week but less than 6 weeks between them* 2 years
Age 2 - 6 years Two doses with an interval of at least one 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 [12, 15].

 

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 [15].

Administration

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 [15].

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 [3]. The vaccine does not provide protection against V cholerae 0139.

Contraindications

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

Adverse events

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 [15].

First Published :   20 Dec 2017
Last Updated :   20 Dec 2017

  1. World Health Organization. Cholera fact sheet. Updated December 2017 [Accessed December 2017]
  2. World Health Organization. Cholera vaccines: WHO position paper – August 2017. WER 25 August 2017. No 34, 92: 477 - 500
  3. Hill DR, Ford L, Lalloo DG. Oral cholera vaccines: use in clinical practice. Lancet Infect Dis 2006; 6: 361 – 73
  4. Ali, M, Nelson AR, Lopez AL, Sack DA. Updated Global Burden of Cholera in Endemic Countries. PLoS Trop Dis 2015 Jun; 9 (6)
  5. Harris JB, LaRocque RC, Qadri F, Ryan ET, Calderwood SB. Cholera. Lancet 2012 Jun 30; 379 (9835): 2466 - 2476
  6. World Health Organization, Cholera, 2015. WER 23 Sept 2016. No 38, 91: 433 – 440
  7. Whittlinger F, Steffen R, Watanabe H, Handszuh H. Risk of cholera among western and Japanese travellers. J Travel Med 1995; 2: 154 – 58
  8. Sanchez JL, Taylor DN. Cholera. Lancet 1997; 349: 1825 – 30
  9. Mahon BE, Mintz ED, Greene KD, wells JG, Tauxe RV. Reported cholera in the United States, 1992 – 1994. JAMA 1996; 276: 307 – 12
  10. Morger H, Steffen R, Schar M. Epidemiology of cholera in travellers, and conclusions for vaccination recommendations. BMJ 1983; 286: 184 - 86
  11. Taylor DN, Rizzo J, Meza R, Perez J, Watts D. Cholera among Americans living in Peru. Clin Infect Dis 1996; 22: 1108- 09
  12. Public Health England. Immunisation against Infectious Disease. Chapter 14 Cholera. December 2013
  13. Public Health England. Cholera in England and Wales: 2011-12 update [Accessed December 2017]
  14. British Medical Association. Focus on travel immunisation, 28 October 2016. [Accessed December 2017]
  15. Valneva UK Ltd, Summary of Product Characteristics Dukoral. 7 December 2015 [Accessed December 2017]

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