What is cholera?

Cholera is an illness cased by a bacterium called Vibrio cholerae. The illness can be mild and may even not lead to any symptoms. However, in many cases it causes severe diarrhoea, sometimes with vomiting. This can quickly lead to serious dehydration and can even be fatal. Cholera is usually caught from drinking infected water or eating infected shell-fish and other foods.

The worst affected areas are the Indian sub-continent, the Far East, Africa and South America. The risk to travellers even in infected areas is still quite small.

Preventing cholera

The most important part of prevention is to be very careful about personal, food and water hygiene. This is most important in areas where sanitation is poor and where there is a risk of catching cholera. You should not drink any water that is untreated and be very careful what you eat. This not only applies to cholera but also to all sorts of other water-borne infections found in areas of poor sanitation.

Cholera immunisation

A new oral vaccine (Dukoral®) became available in the UK in 2004. This is now the only vaccine for cholera available in the UK. It is not advised for most travellers. It may be advised for certain people travelling to places where cholera may occur. Your doctor or nurse will advise if you should consider having this vaccine. Examples of people who are likely to be advised to have this vaccine include:

• People going to work in an area of a known cholera outbreak. For example, aid workers, health workers, etc, who will be working in emergency relief camps where cholera has broken out.
• People planing to stay a long time in an area where cholera is high risk. Especially to areas where there is limited access to medical care.

The vaccine

The oral vaccine comes in sachets which are dissolved in a drink. It can be used by adults and children aged two years and over. You should not eat or drink anything for an hour before and after taking a dose of the vaccine. This is to make sure it is absorbed fully from your gut.

The course of immunisation is two doses for people over six years old and three doses for children 2-6 years old. Each dose is given at least one week apart but no later than six weeks apart. The course of immunisation should be finished at least one week before potentially coming into contact with cholera. Typically, this is one week before travel.

A booster dose is needed to maintain protection. This is after two years for people over six years old, and after six months for children 2-6 years old. The cholera vaccine can be given at the same time as other injected vaccines.

Note: the vaccine does not provide complete protection. For example, it does not protect against all strains of cholera. Therefore, it is still important that you are careful with regard to what you eat and drink in the usual way.

Who should not receive the vaccine?

There are very few people who cannot have the oral cholera vaccine. It should not be given if:

• You have had a severe reaction to a previous dose of the oral cholera vaccine.
• You have had a severe (anaphylactic) reaction to formaldehyde or any of the ingredients of the vaccine.

There is currently no data on the safety of this vaccine in pregnant or breastfeeding women. Therefore, if you are pregnant or breastfeeding the vaccine should only be considered if the risk of cholera is high.

Side effects from this vaccine are uncommon. Less than 1 in 100 people develop some abdominal pains, diarrhoea or nausea for a short time after taking the vaccine.

Further information

Information on immunisation from the NHS

Web: www.nhs.uk/Planners/vaccinations/Pages/Travelvaccines.aspx

Health Advice for Travellers

All travellers going abroad are advised to get this booklet by the Department of Health. You can get a free copy from main post offices.

Patient UK Travel Health Page

Web: www.patient.co.uk/showdoc/38
Has a comprehensive list of links to UK websites on travel health.

References

• Immunisation against infectious disease - 'The Green Book', Dept of Health (various dates)
• Longini IM Jr, Nizam A, Ali M, et al; Controlling endemic cholera with oral vaccines. PLoS Med. 2007 Nov 27;4(11):e336. [abstract]