Cholera
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.
Additional
notes
-
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.
