Malaria

How can you avoid this potentially serious problem?

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Malaria occurs in much of the tropical world and represents a real hazard for travelers who lack any level of immunity to the malaria parasites in these areas. The map below shows the world distribution of malaria.

In some respects, this map may be misleading, because the transmission of malaria may be very localized geographically. If one could zoom into the map further, one would find malaria-free zones within these shaded areas, particularly in large cities or in heavily-touristed areas. In addition, the malaria parasites in different parts of the world have different degrees of virulence (i.e., capacity to cause severe disease) and variable susceptibility to the available antimalarial medications. Drugs that work to prevent malaria in one part of the shaded areas may be completely ineffective in other areas. Therefore, it is essential to have current, detailed information about the risk and the nature of the malaria strains within these shaded zones in order to recommend preventive measures effectively and only when necessary.

If your travel plans involve only the unshaded areas of the map (white areas), you do not need to consider preventive treatment for malaria.

Options for Prevention of Malaria

Mosquito avoidance: Since malaria can only be acquired by a mosquito bite (or rarely, by blood transfusion), absolute avoidance of mosquitoes is one way to prevent the disease. Therefore, insect repellents, screened habitats, and bed nets are all helpful. These measures are summarized in another document in this site. Unfortunately, in most places where malaria is transmitted, complete avoidance of mosquitos is almost impossible. Therefore, we do not recommend relying on these methods as the sole protection against malaria during travel (Note: it may be possible to shield infants who are transported in car seats or strollers equipped with screening.)

Vaccines: It would be fantastic to have one, but an effective vaccine for travelers has not yet been developed. Malaria vaccines in clinical trials currently are designed to reduce -- not completely eliminate -- the risk for residents of malarious areas. It is doubtful that a malaria vaccine for travelers will replace antimalarial prophylaxis in the foreseeable future.

Antimalarial prophylaxis: Preventive treatment with medications is the best and most reliable method of avoiding this serious hazard. The prescription of an antimalarial for any particular traveler depends on the travel itinerary, the duration of travel, the individual's past use and tolerance of antimalarial medications, and the traveler's medical history.

The following table lists the medications that are commonly prescribed to U.S. travelers to prevent malaria, summarizing the advantages and disadvantages of each:

Medication

Method of Use

Advantages

Disadvantages

Chloroquine (Aralen)

Taken weekly. Begin 1-2 weeks before travel and continue for 4 weeks after return to a non-malarious area

This is safest and most widely-used antimalarial. Serious adverse effects are extremely rare.

Virulent malaria strains in most parts of the world are now resistant to this drug. It is still useful in Central America and the Caribbean.

Mefloquine (Lariam)

Taken weekly. Begin 1-2 weeks before travel and continue for 4 weeks after return to a non-malarious area

This drug can be used effectively and long-term in most areas of the world. It is active against strain resistant to chloroquine.

Some travelers have significant adverse effects:
• Stomach upset on the day the medication is taken
• Neuropsychiatric symptoms, such as nightmares or worsening of pre-existing psychiatric disorders.
•May interfere with some cardiac medications.

Atovaquone/proguanil (Malarone)

Taken daily. Begin 1-2 days prior to travel, continue taking daily while traveling, and continue taking daily for 7 days after return to a non-malarious area

Effective in virtually all areas of the world. Resistance is extremely rare.

Expensive. The cost may be prohibitive for long-term travel (> a few months)

Doxycycline

Taken daily. Begin 1-2 days prior to travel, continue taking daily while traveling, and continue taking daily for 4 weeks after return to a non-malarious area

Effective in most areas of the world.
Inexpensive to use long-term (> a few months).

Some travelers may have adverse effects:
• sensitivity to the sun (exaggerated sunburn)
• stomach upset if taken on without food
• vaginal yeast infection in women

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