Information on malaria risk in specific countries (pp. 13-73) is derived from various sources, including the World Health Organization. While this is the most accurate information available at the time of publication, factors that may vary from year to year, such as local weather conditions, mosquito vector density, and prevalence of infection, can have a marked effect on local malaria transmission patterns.
Thus, most imported P. falciparum malaria among American travelers was acquired in Africa south of the Sahara, even though only 130,000 arrivals from the United States were reported by countries in that region in 1991. In contrast, 20 million arrivals from the United States were reported that year in other countries with malaria (including15 million travelers to Mexico, (World Tourism Organization). This disparity in the risk of acquiring malaria reflects the fact that travelers to Africa tend to spend considerable time, including evening and nightime hours, in rural areas where malaria risk is highest. Travelers to Asia and South America, however, spend most of their time in urban or resort areas where there is limited, if any, risk of exposure and travel to rural areas mainly during daytime hours when the risk of infection is limited.
Estimating the risk of infection for different categories of travelers is difficult and may be significantly different even for persons who travel or reside temporarily in the same general areas within a country. For example, tourists staying in air conditioned hotels may be at lower risk than backpackers or adventure travelers. Similarly, longer-term residents living in screened and air-conditioned housing are less likely to be exposed than are missionaries or Peace Corps volunteers.
No hay imagen. Distribution of Malaria and Chloroquine-resistant Plasmodium falciparum, 1995
Travelers should use a pyrethroid-containing flying-insect spray in living and sleeping areas during evening and nighttime hours. In addition, persons who will not be staying in rooms which are well-screened or air-conditioned should take additional precaution, which include sleeping under mosquito netting, i.e., bednets. Permethrin (Permanone(R)) may be sprayed on clothing and bednets for additional protection against mosquitoes. Bednets are more effective if they are treated with permethrin or deltamethrin insecticides. In the United States permethrin spray or liquid can be used, while permethrin or deltamethrin liquid may be purchased overseas for the treatment of bednets.
Malaria chemoprophylaxis should preferably begin 1-2 weeks before travel to malarious areas (except for doxycycline, which can begin 1-2 days before). This allows any potential side effects to be evaluated and treated by the traveler's physician before departure. Chemoprophylaxis should continue during travel in the malarious areas and for 4 weeks after leaving the malarious areas.
Table 13a. Drugs used in the prophylaxis of malaria
Table 13b Drugs used in the presumptive treatment of malaria
Regimen B: For travel to areas of risk where chloroquine-resistant P. falciparum exists, use of mefloquine alone is recommended. Mefloquine is usually well tolerated but precautions should be observed as described in the section on adverse reactions. Mefloquine prophylaxis should begin 1-2 weeks before travel to malarious areas. It should be continued weekly during travel in malarious areas and for 4 weeks after a person leaves such areas. Mefloquine can be used for long-term prophylaxis. (See Table 13a for recommended dosages.) Note: In some foreign countries a fixed combination of mefloquine and Fansidar(R) is marketed under the name Fansimef(R). Fansimef(R) should not be confused with mefloquine, and it is not recommended for prophylaxis of malaria because of the potential for severe adverse reactions associated with prophylactic use of Fansidar(R).
Doxycycline alone taken daily is an alternative regimen for travelers who cannot tolerate mefloquine or for whom the drug is not recommended. Doxycycline is as effective as mefloquine for travel to most malarious areas. However, it is also the only available effective prophylactic drug for prophylaxis for travelers to malaria endemic areas of Thailand. Travelers who use doxycycline should be cautioned about the possible side effects as described in the section on adverse reactions. Doxycycline prophylaxis should begin 1-2 days before travel to malarious areas. It should be continued daily during travel in malarious areas and for 4 weeks after the traveler leaves such areas. (See Table 13a for recommended dosages.)
Chloroquine alone taken weekly is only recommended for those travelers to areas with drug-resistant P. falciparum who cannot use mefloquine or doxycycline. Limited data suggest that the combination of chloroquine with daily proguanil (Paludrine(R)*) is more effective than chloroquine alone in Africa, but not in Thailand and Papua New Guinea. Therefore, travelers to Africa who use chloroquine for prophylaxis should, if possible, also take 200 mg daily (adult) of proguanil. Proguanil is not available commercially in the United States but can be obtained in Canada, Europe and many African countries.
Mefloquine should not be used for self-treatment because of the frequency of serious side effects (e.g., hallucinations, convulsions) that have been associated with the high dosages of mefloquine used for treatment of malaria.
Halofantrine (Halfan(R)) is an antimalarial drug which is licensed in the United States but is not commercially available, although the drug is available in many other countries. Halofantrine is not recommended for self-treatment of malaria because of potentially serious electrocardiogram changes which have been documented following treatment doses of halofantrine: in many of these reports halofantrine was administered in the presence of other antimalarial drugs (for example, mefloquine). The safety of halofantrine for self-treatment of persons on mefloquine prophylaxis has not been established and, since halofantrine is widely available overseas, health care providers may choose to caution travelers to avoid the use of halofantrine if they are on mefloquine.
Since most malarious areas of the world (except Haiti) have at least one species of relapsing malaria, travelers to these areas have some risk of acquiring either P. vivax or P. ovale, although the actual risk for an individual traveler is difficult to define. Prophylaxis with primaquine is generally indicated only for persons who have had prolonged exposure in malaria-endemic areas, e.g., missionaries and Peace Corps Volunteers. Most people can tolerate the standard regimen of primaquine, with the exception of individuals deficient in glucose-6-phosphate dehydrogenase (G6PD) (see discussion of adverse reactions). (See Table 13a for recommended dosages.)
Chloroquine and hydroxychloroquine rarely cause serious adverse reactions when taken at prophylactic doses for malaria. Minor side effects that may occur include gastrointestinal disturbance, headache, dizziness, blurred vision, and pruritus, but generally these effects do not require that the drug be discontinued. High doses of chloroquine, such as those used to treat rheumatoid arthritis, have been associated with retinopathy, but this serious side effect has not been associated with routine weekly malaria prophylaxis. Chloroquine and related compounds have been reported to exacerbate psoriasis. Chloroquine may interfere with the antibody response to human diploid cell rabies vaccine when the vaccine is administered intradermally.
Mefloquine has rarely been associated with serious adverse reactions (e.g., psychoses, convulsions) at prophylactic dosage, but these reactions are more frequent with the higher dosages used in treatment. Minor side effects observed with prophylactic doses, such as gastrointestinal disturbance, insomnia, and dizziness, tend to be transient and self-limited.
Mefloquine is contraindicated for use by travelers with a known hypersensitivity to mefloquine and is not recommended for use by children <15 kg. (30 lbs.), and travelers with a history of epilepsy or severe psychiatric disorders. A review of available data suggest that mefloquine may be used in persons concurrently on beta blockers, if they have no underlying arrhythmia. However, mefloquine is not recommended for persons with cardiac conduction abnormalities until additional data are available. Caution may be advised for travelers involved in tasks requiring fine coordination and spatial discrimination, such as airline pilots.
All studies to date confirm that mefloquine is well tolerated when used for prophylaxis; however, monitoring the occurrence of severe adverse reactions is important because such reactions are possible. Users of mefloquine prophylaxis who experience serious adverse reactions should consult their physician, and the reactions should be reported to the Malaria Section, CDC, telephone (770) 488-7760.
Doxycycline may cause photosensitivity, usually manifested as an exaggerated sunburn reaction. The risk of such a reaction can be minimized by avoiding prolonged, direct exposure to the sun and by using sunscreens that absorb long-wave ultraviolet (UVA) radiation. In addition, doxycycline use is associated with an increased frequency of monilial vaginitis. Gastrointestinal side effects (nausea or vomiting) may be minimized by taking the drug with a meal. To reduce the risk of esophagitis, doxycycline should be taken before going to bed. Doxycycline is contraindicated in pregnancy and in children less than 8 years of age.
Fansidar(R) is contraindicated in persons with a history of sulfonamide intolerance and in infants less than 2 months of age.
Proguanil rarely causes serious adverse reactions at prophylactic dosage. Reported side effects include nausea, vomiting, mouth ulcers, and hair loss.
Primaquine may cause severe hemolysis in G6PD-deficient individuals. Before primaquine is used, G6PD deficiency should be ruled out by appropriate laboratory testing.
Chloroquine phosphate is manufactured in the United States in tablet form only and has a very bi