What is cholera, how is it spread, and how is it treated?
Cholera is caused by bacteria, Vibrio cholerae , that contaminate water or food, especially fish or shellfish. Persons can avoid cholera by not eating raw or undercooked food and by not drinking water that has not been boiled, filtered, or chemically disinfected. (Ice cubes in drinks often are made from untreated water.) Cholera is common in Central and South America, Asia, and Africa. Usually the disease occurs in areas of poverty, not in tourist sites where facilities and funds are available to treat the water and to prepare the food more carefully. About 1 in 500,000 returning Western travelers report getting cholera.
One to three days after exposure, the poison produced by the cholera bacteria will give infected persons diarrhea, often with vomiting but without fever. Only 2 to 5 percent of infections are severe, but cholera can lead to a rapid and life-threatening loss of fluids and body salts. Because the bacteria are killed by stomach acids, few persons get sick with cholera unless they ingest a large amount of the bacteria in a heavily contaminated source or their stomach acids have been diminished by antacids or anti-ulcer medications. Others at risk include persons with liver disease or immunodeficiency.
The main treatment is large amounts of rehydrating fluids. Oral rehydration solution (ORS), prepared from packets of rehydration salts distributed by the World Health Organization, is the best fluid to drink because it contains the optimal mix of body salts. (ORS packets are available in the U.S. from Jianas Brothers Packaging Company, Kansas City, MO; telephone 816-421-2880.) Commercial rehydration products, such as Pedialyte, are also effective but are bulky to pack. Of course, if the patient vomits all the fluids taken by mouth, then intravenous fluids may be needed.
Persons who have moderate to severe cholera can take antibiotics to shorten the course of the illness. The cholera bacteria, however, are becoming increasingly resistant to some of the common antibiotics.
How effective is the cholera vaccine, and who should get it?
The cholera vaccine protects only about 50 percent of the persons who are injected with it, and it is completely ineffective against some strains of the bacteria. Two doses are recommended for people at highest risk and should be given one week to one month or more apart. Boosters are necessary every six months if the risk of disease persists. Protection starts about two weeks after the second dose.
Luckily, the risk of cholera is so low that the vaccine is not recommended for U.S. travelers. And no country currently requires cholera vaccine for entry. Despite World Health Organization recommendations, however, local authorities in some areas (such as in Africa) demand proof of cholera vaccination or a medical exemption certificate for entry. If you have neither of these, you may be faced with having your itinerary rearranged abruptly or with border patrol offering on-the-spot single dose cholera vaccination (which greatly increases your risk of HIV and hepatitis B). Some travel experts suggest that vaccination or official exemption may be advisable if you are going to or through an African country where cholera is active.
The cholera vaccine may be of benefit for three groups of international travelers:
Persons taking antacids or anti-ulcer medications (such as Zantac, Tagamet, Prevacid, Prilosec). Remember that stomach acids are the best line of defense when contaminated food or drink is consumed.
Persons who will be in areas of poor sanitation for a prolonged time (such as famine relief workers in refugee camps in endemic areas).
Persons traveling to areas where there is no prompt access to reliable medical care (such as backpackers).
Who should not get the vaccine?
Persons with a history of a severe allergic or systemic reaction following a prior dose of cholera vaccine or any of its components should not take cholera vaccine.
Others who should avoid the vaccine include the following:
Persons who have a moderate or severe acute illness. These individuals should postpone vaccination.
Children less than 6 months old. (For older children the dose and route of cholera vaccine is age-dependent. Seek advice from a knowledgeable healthcare provider.)
Pregnant women. A pregnant woman should only receive the cholera vaccine if it is clearly needed.
What are the vaccine risks and side effects?
Cholera vaccination is associated with more local side effects than most other vaccines. Most persons experience pain, swelling, and redness at the cholera vaccine injection site. This may begin soon after the shot and usually resolves within a few days. Frequently persons experience malaise, headache, and mild to moderate fever for a day or two after cholera vaccine. Severe allergic reactions and other severe reactions occur rarely after cholera vaccine.
Vaccination for yellow fever and cholera should be separated by at least three weeks because these vaccines interfere with each other.
Plague vaccine and the injectable typhoid vaccine often cause side effects similar to the cholera vaccine. Theoretically, getting these vaccines at the same time could lead to a bigger reaction. If you have time, you may be more comfortable if you separate vaccinations by a week or more before leaving.
Cholera vaccines that are taken by mouth are more effective. Though available in several other countries, they are not licensed in the U.S.
Mutachol is a drug available in Canada, Europe, and Latin America that is 86 percent effective in preventing any diarrhea from cholera, and it is well tolerated. It is produced by Berna Pharmaceuticals.
This information is excerpted from the book Vaccinating Your Child: Questions and Answers for the Concerned Parent (Peachtree Publishers, Ltd., 2000). The book’s authors are Dr. Sharon G. Humiston, a pediatrician and clinical researcher at the CDC and the University of Rochester, and Cynthia Good, an award-winning journalist and host of the television show “Good for Parents”.