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Should You Take Drugs to Prevent Malaria or Not?

Should You Take Drugs to Prevent Malaria or Not?

Should you take drugs to prevent malaria or not? This is not an easy question

to answer in Cambodia for four main reasons:

  1. The risk of malaria varies widely from place to place in Cambodia.
  2. No drug for prevention (prophylaxis) is completely safe.
  3. Most drugs against malaria have some side-effects.
  4. 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.

Always Remember:

  • You should not rely on prophylaxis by drugs alone; always protect yourself from

    mosquito bites.

  • 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.


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