PREVENTION OF MALARIA: CHEMOPROPHYLAXIS
A number of medications have been shown to have efficacy in preventing malaria infection. As with all treatments, the use of an antimalarial regimen should weigh the potential adverse effects against the risk of acquiring malaria. The clinician must review the travel itinerary to assess the risk of malaria exposure and recognize areas of travel within drug-resistant zones. Contraindications to the use of specific antimalarials for that patient should be identified.
Chloroquine-resistant P. falciparum exists throughout the entire malaria endemic world except for Mexico, Central America west of Panama, Argentina, the Caribbean, parts of China, and parts of the Middle East. P. falciparum in any other part of the world must be assumed to be chloroquine-resistant. P. falciparum that is resistant to both mefloquine and chloroquine can be found in Southeast Asia along the Thailand-Myanmar (formerly Burma) and the Thailand-Cambodia borders. Chloroquine-resistant P. vivax is also becoming an important problem, particularly in Papua New Guinea, Irian Jaya, Vanuatu, Myanmar, and Guyana.
Because of the emergence of drug-resistant P. falciparum strains, chloroquine (Aralen, Sanofi-Synthelabo) is no longer the recommended chemoprophylaxis medication for most parts of the world. Chloroquine is still recommended for prophylaxis for travel to Central America west of the Panama Canal, Hispaniola (Haiti and the Dominican Republic), Argentina, parts of China, and parts of the Middle East (primarily Syria, Jordan, and Iraq). The antimalarial dosage for a traveler to these areas is one 500 mg tablet (300 mg base) per week beginning 2 weeks before departure, one tablet weekly during exposure, and one tablet per week for 4 weeks after the trip. The most common side effect is dyspepsia, but it can also cause pruritus (especially in dark-skinned individuals), exacerbations of psoriasis, agranulocytosis, photosensitivity, and, rarely, neuropsychiatric disturbances such as vertigo or insomnia. The drug is a safe option during pregnancy. Concurrent use of chloroquine interferes with antibody response to the intradermal administration of the human rabies vaccine.
Mefloquine (Lariam, Hoffman-LaRoche) is the drug of choice for most travelers to chloroquine-resistant regions. The traveler takes a 250 mg tablet once a week for 2 weeks before departure, then takes a dose weekly during travel, followed by one dose per week for 4 weeks after returning home. In the past decade, many anecdotal reports of neuropsychological adverse effects have raised major concerns about this drug. However, adverse effects are similar in frequency and severity to those reported with weekly chloroquine use. The most commonly reported side effects include nausea, dizziness, headaches, and vivid dreams. Mefloquine should be used with caution in patients with a history of psychosis, seizure disorder, or cardiac conduction defects. It is the most efficacious and safe option for the prevention of malaria in pregnant women traveling to areas with chloroquine-resistant P. falciparum.
This entry was posted on Friday, February 11th, 2011 at 2:30 pm and is filed under CHEMOPROPHYLAXIS. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.
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