Should you take drugs to prevent malaria or not? This is not an easy question
to answer in Cambodia for four main reasons:
- The risk of malaria varies widely from place to place in Cambodia.
- No drug for prevention (prophylaxis) is completely safe.
- Most drugs against malaria have some side-effects.
- Malaria is very dangerous, especially if it is treated late, so every possible
way to prevent it should be used.
Based on a consensus of malaria specialists' opinions, UNTAC personnel-who are
working all over Cambodia for periods up to two years-have been advised to take doxycycline
(100 mg. per day) for prophylaxis, starting medication one week before entering a
malarious area and continuing for four weeks after leaving. This recommendation could
apply to any temporary visitor to malarious parts of Cambodia.
While the risk of malaria is extremely low in Phnom Penh and Battambang city and
in certain other major towns, drug prophylaxis is strongly recommended for temporary
visitors to the rest of the country, as malaria can kill very quickly (occasionally
even less than two days after symptoms start).
There is always the risk that it may not not be diagnosed and treated with the right
drugs in time. The symptoms are not always obvious, and there may be delays in finding
a doctor. Each extra preventative method you use reduces your risk of being infected.
The following outlines the effectiveness and side effects of the various drugs
you may have heard suggested for prophylaxis:
Doxycycline: a tetracycline antibiotic, which has been recommended in recent
years for prophylaxis in areas with drug resistance to Falciparum malaria. It has
not been widely used yet, but studies in Thailand showed it greatly reduced the chances
of contracting malaria, although it is not 100 percent effective.
Severe side effects are very rare with doxycycline, and studies of people taking
it for a long time for other conditions showed no increase in side effects.
While some people experience nausea when taking doxycycline, it may also prevent
travellers' diarrhea. Taking the drug does not seem to increase the chance of infection
with drug-resistant stomach bacteria.
You should take the drug with water, and should not lie down immediately afterwards.
Those who are more susceptible to sunburn should consult a doctor before taking doxycycline.
Certain fungal infections are more frequent in women on doxycyline. Pregnant women,
and children under eight years old should not take doxycycline.
Mefloquine (Lariam™): This has been used as an effective and simple
treatment of Plasmodium falciparum in Thailand since 1984. It has not yet been used
widely in Cambodia, but will be introduced into some hospitals in the northwest,
where there is a high resistance to chloroquine and Fansidar™.
Unfortunately, resistance to mefloquine is increasing rapidly in Thailand. So far,
it is still very effective for treatment in parts of Cambodia, but there is probably
much resistance on the Thai border, especially near Pailin. It is probably effective
for prophylaxis in many parts of Cambodia, but the policy is to restrict its use
to treatment to delay development of mefloquine resistance.
The main side effects of mefloquine are mild, and no worse than with other anti-malarial
drugs. There is, however, increasing concern about reports of neurological and psychological
effects. No severe effects of this type have been reported in trials of mefloquine
prophylaxis, but mild effects such as dizziness, depression, headache, sleeping disorders,
visual disturbances and disorders of balance have occurred-although it is not certain
they were related to the drug.
More severe effects have been reported with treatment doses (as opposed to preventative
doses), including rare cases of acute psychosis. It has therefore been recommended
that people involved in activities requiring fine coordination, such as airline crews
and people operating heavy or dangerous equipment, do not use mefloquine prophylaxis.
At present it is not recommended as prophylaxis for pregnant women.
Chloroquine: Although effective for prevention of Plasmodium vivax,
chloroquine is no longer effective against Plasmodium falciparum in most of Cambodia.
Severe side effects of chloroquine prophylaxis are very rare, although eye damage
is possible if chloroquine is taken regularly over several years. Overdosing is dangerous,
so keep tablets away from children.
Sylfadoxine-Pyrimethamine (Fansidar™) and Amodiaquine: Not recommended
for prophylaxis. They are unlikely to be effective in parts of Cambodia, and can
have very severe side effects. In certain areas of Cambodia, Fansidar can safely
be used for treatment only.
Dapsone and Pyrimethamine (Maloprim™): Unlikely to be effective
here, and can have severe side effects on white blood cells.
Proguanil (Paludrine™): Although proguanil does not have severe side effects,
it is unlikely to be effective here.
Qinghaosu (Artemisinin, Artesunate): These are not recommended for
prophylaxis, as they stay in the blood for a very short time, and toxicity studies
have not been finished. As these drugs may one day be our only weapon for treatment
of severe malaria in Cambodia, it is essential that we do not use them carelessly
now, and thus encourage Plasmodium falciparum to become resistant to them.
Halofantrine and Quinine: Not used for prophylaxis.
- You should not rely on prophylaxis by drugs alone; always protect yourself from
- Even if you take drug prophylaxis, you may still get malaria (although the risk
will be lower). It is essential to seek medical advice and have a blood test if you
have any symptoms of malaria.
- Almost all malaria deaths result from seeking treatment too late. Even one day's
delay may be too long.