27 June 2006

 

Cholera outbreaks and advice for travellers

 

Cholera is an acute diarrhoeal disease caused by the gram negative bacillus Vibrio cholerae. Although there are more than 100 serogroups, only two are known to cause human infection: V. cholerae O1 and V. cholerae O139.

V. cholerae is endemic in many resource-poor countries, particularly in areas of inadequate sanitation and food and water hygiene. In 2004, a total of 101,383 cases of cholera from 56 countries were reported to the World Health Organization (WHO) [1]. The number of officially reported cases is likely to considerably underestimate the true number of cases.

Large outbreaks of cholera are occurring in Angola and Sudan and have been reported by the World Health Organization (WHO) [2,3]. These provide the opportunity to review indications for cholera vaccine in travellers.

Angola

As of 19 June 2006, a total of 46,758 cases of cholera including 1,893 deaths (case fatality rate, CFR 4%), had been reported in Angola [2]. Fourteen out of the 18 provinces in Angola have been affected; 49% of cases have occurred in Luanda province.

Although current trends indicate a decline in cases in most provinces, a daily incidence of approximately 125 cases continues to be reported. The WHO is supporting the Angolan Ministry of Health in surveillance, water and sanitation, social mobilization and logistics activities.

Sudan

Between 21 April and 18 June 2006, the Federal Ministry of Health (FMoH) has reported a total of 2,007 cases of acute diarrhoeal illness, including 77 deaths (CFR 3.8%) from northern Sudan [3]. Nine of the 15 northern Sudan states have been affected, with 35% of cases occurring in Khartoum state. Serotype O1 Inaba has been confirmed in 70 out of 139 stool samples so far collected.

Between 28 January and 14 June 2006, a total of 16,187 cases of acute diarrhoeal illness, including 476 deaths (CFR 3%) were reported in southern Sudan [3]. Eight of the 10 southern Sudan states have been affected. V. cholerae O1 Inaba has been laboratory confirmed in several stool samples.

Task forces which include personnel from the FMoH, WHO and other non-governmental partners, has been formed to coordinate the public health response.

Advice for travellers

Although outbreaks of cholera are regularly reported from resource-poor countries, the risk to travellers remains small. Very few travellers are exposed to the poor conditions associated with cholera outbreaks. Between 1990 and 2003, between three and 23 cases each year were reported in England and Wales, with an annual average of 10 cases [4].

For most travellers, advice on food and water hygiene precautions is adequate to prevent cholera. An oral cholera vaccine, Dukoral® is available in the UK for travellers who are at specific risk. The vaccine is active against the O1 strain of V. cholerae. Specific indications for cholera vaccine include:

• Aid workers assisting in disaster relief or refugee camps
• travellers on remote itineraries in countries with cholera outbreaks who have only limited access to medical care.

More information on Dukoral® can be found on the Summary of Product Characteristics (SPC) available online at: http://emc.medicines.org.uk/emc/assets/c/html/

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References

1. World Health Organization. Cholera 2004. Wkly Epid Rec 31:261-268, 2005. Available online at http://www.who.int/wer/2005/wer8031.pdf

2. World Health Organization. Cholera in Angola - update 5. 21 June 2006. [cited 27 June 2006] Available online at: http://www.who.int/csr/don/2006_06_21/en/

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3. World Health Organization. Cholera in Sudan - update 4. 21 June 2006. [cited 27 June 2006] Available online at: http://www.who.int/csr/don/2006_06_21a/en/

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4. Health Protection Agency. Foreign travel-associated illness. England, Wales, and Northern Ireland - Annual report 2005. London: Health Protection Agency Centre for Infections; 2005. Available online at http://www.hpa.org.uk/publications/2005/travel

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Links and further reading

NaTHNaC Cholera information sheet

http://www.NaTHNaC.org/pro/factsheets/cholera.htm

Hill DR, Ford L, Lalloo DG. Oral cholera vaccines: use in clinical practice. Lancet Infect Dis 6:361-373, 2006.