Rationale:

• Appropriately prescribed antimalarial therapy is highly effective, resulting in rapid and complete resolution of symptoms and a negative thick smear at the completion of therapy.
• A small proportion of patients may experience a recrudescence with either drug-resistant parasites or relapse with parasites derived from inadequately treated hypnozoites in the liver.
• Drug-resistant malaria parasites today are a common cause of treatment failure.

Evidence:

• In addition to cases of resistance involving chloroquine, sulfadoxine-pyrimethamine, and mefloquine, atovaquone-proguanil resistance has been reported in a traveler from West Africa who was initially treated with atovaquone-proguanil for uncomplicated malaria. Four weeks later, the patient experienced recrudescence with an atovaquone-proguanil-resistant strain (111) requiring treatment with quinine-doxycycline.
• Short courses of primaquine have proved inadequate in preventing relapse of some P. vivax strains. In one study involving 500 P. vivax malaria cases in Pakistan, a 5-day course of primaquine failed to prevent second and third relapses when compared to chloroquine alone (142). In another study involving 180 P. vivax malaria cases in India, relapse rates over 6 months of follow-up were 0% with the 14-day primaquine regimen, 27% with the 5-day primaquine regimen, and 12% with no primaquine (135).

Comments:

• The American Red Cross has issued the following guidelines for donating blood: “Wait 3 years after completing treatment for malaria. Wait 12 months after returning from a trip to an area where malaria is found. Wait 3 years after moving to the U.S. after living in a country where malaria is found.”