Antimalarials chemoprophylaxis

Include a careful travel history of patient and physical findings (e.g., splenomegaly) and details of antimalarial chemoprophylaxis, when obtainable. 

Weekly dosing with mefloquine for chemoprophylaxis may cause nausea, vomiting, dizziness, sleep and behavioral disturbances, epigastric pain, diarrhea, abdominal pain, headache, rash, and dizziness. Neuropsychiatric toxicities have received a good deal of publicity, but despite frequent anecdotal reports of seizures and psychosis, a number of controlled studies have found the frequency of serious adverse effects from mefloquine to be no higher than that with other common antimalarial chemoprophylactic regimens. Leukocytosis, thrombocytopenia, and aminotransferase elevations have been reported. 

Clindamycin (see Chapter 44) is slowly active against erythrocytic schizonts and can be used after treatment courses of quinine, quinidine, or artesunate in those for whom doxycycline is not recommended, such as children and pregnant women. Azithromycin (see Chapter 44) also has antimalarial activity and is now under study as an alternative chemoprophylactic drug. Antimalarial activity of fluoroquinolones has been demonstrated, but efficacy for the therapy or chemoprophylaxis of malaria has been suboptimal. 

The adverse effects of mefloquine have been extensively reviewed both for prophylaxis (when rare neuropsychiatric adverse effects make its use controversial) and in treatment doses, when it has been linked to an increased incidence of the postmalaria neurological syndrome. A retrospective review of 5120 Itahan soldiers showed an overall chemoprophylaxis curtailment rate of less than 1%, which was not significantly different from the combination of chloroquine and proguanil (11). A semi-systematic review also suggested no significant difference in tolerabihty compared with other antimalarial drugs (12). 

Pyrimethamine and proguanil are used as oral antimalarials.and inhibit the utilization of folate by the malarial parasite, so are valuable in chemoprophylaxis and in preventing the transmission of malaria. (See ANTIMALARIALS.) Trimethoprim is a useful antibacterial, and as an antiprotozoal in antimalarial therapy. The selectivity of these agents derives, in part, from the fact that whereas mammals can obtain folic acid from the diet, bacteria and the asexual forms of the malarial parasite must synthesize it. Also, the dihydrofolate reductase enzyme in humans is less sensitive to these drugs than that of the parasites. 

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