Malaria prophylaxis is a major problem for international travelers because of the increase in drug resistance and the toxicities of existing antimalarial drugs (e. g.. Fansidar). The need for, and the type of, prophylaxis is usually dependent upon the exact itinerary within a given country. For example, malaria does not occur in most urban centers in Southeast Asia such as Bangkok, but highly drug-resistant strains of Plasmodium falciparum may be encountered just a few miles into the countryside. Recommended chemoprophylactic regimens change frequently and are often out of date in textbooks. Detailed information on malaria risk is contained in the annual "Health Information for International Travel", which is updated frequently.

Travelers to areas where chloroquine sensitive P. falci parum strains are common (Central America, most parts of India and Southeast Asia, the Middle East, and most parts of West Africa) should take chloroquine phosphate (300 mg base or 500 mg salt) weekly starting two weeks before, during, and for six weeks after leaving malaria endemic areas. No completely safe and effective chemoprophylaxis is available for chloroquine resistant P. falci parum malaria. Therefore, travelers, in addition to taking weekly chloroquine, should carry antibiotics for presumptive treatment for acute malaria (three tablets of pyrime thamine/sulfadoxine sold under the trade name Fansidar), which are self-administered for a temperature over 102°F when appropriate medical care is unavailable.

In sulfa-allergic patients, daily doxycycline (100mg) is given alone. Neither regimen is very effective in Burma or Thailand, where combined chloroquine and Fansidar resistance is common. Combined resistance is a growing problem in East Africa. The preferred chemoprophylaxis in these areas as well as chemoprophylaxis for prolonged travel in any area endemic for chloroquine-resistant malaria is controversial. Recommendations include weekly Fansidar (associated with 1/11 000 to1/25 000 risk of fatal reactions in users) and the use of other drugs in addition to chloroquine (including proquanil and amodiaquine). Some authorities recommend no prophylaxis with instructions to seek medical advice immediately when a fever develops. Emphasis should be given to the use of netting, screens, and insect repellants as well as prompt diagnosis and treatment of any febrile episodes overseas.

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