Transfusion-induced malaria is a problem because of the large number of parasites infused and the weakness of transfused patients. Screening of blood donors or treatment of transfused patients or prospective donors does not eliminate this hazard. It is essential to kill the parasite in vitro in the blood of donors before transfusion. A total of 4,484 blood donors were screened for malaria parasite microscopically using the Giemsa staining technique. Only 30 matched the inclusion criteria of this study. Blood samples were divided into four equal samples. Three concentrations of sulfadoxine-pyremthamine (SP) were added to 90 specimens, and none was added to 30 specimens (controls). Blood specimens were then tested by parasitic, biochemical, and hematologic techniques on the day of collection and after 24 and 48 hours of storage in a blood bank refrigerator. The reduction of malaria parasites was proportional to the concentrations of SP and to the storage period. Blood samples without SP had steady number of the parasites. The lethal dose of SP (the dose that killed 99% of the malaria parasites within 24 hours) was 179.65 mug/L and was highly effective within the 24-hour storage period. This dose did not affect constituents of the stored blood. Thus, for eradication of transfusion-induced malaria by in vitro processing of donors blood, SP is a safe and effective drug. It is recommended that optimal doses of SP be added to donated blood prior to phlebotomy.

Azithromycin has demonstrated activity in a prevention of Plasmodium vivax infection, but no controlled treatment studies have been performed. A double-blinded trial was conducted in P. vivax malaria in which patients were randomized to either azithromycin 1,000 mg q.d. x 3 or chloroquine 600 mg q.d. x 2 then 300 mg on Day 3 followed by primaquine on Days 7 through 20. Eighty-five of 97 (88%) of those on azithromycin and 101 of 102 (99%) of those on chloroquine [difference 11%; 95% CI: -18, -4] were clinically cured at Day 7. The Day 28 results were similar [89% versus 99%, azithromycin versus chloroquine, respectively]. Parasitologic success was seen in 81 of 97 (84%) on azithromycin and 100 of 102 (98%) on chloroquine [difference 14%; 95% CI: -22, -6]. The median parasite clearance time was 55 hours on azithromycin and 20 hours on chloroquine (P < 0.001). Drug-related adverse events were seen in 13 of 98 (13%) on azithromycin and 24 of 102 (24%) on chloroquine (P = 0.062). Resolution of parasitemia was significantly faster with chloroquine compared with azithromycin, but azithromycin was better tolerated. These data provide support for further study of azithromycin to better define its role in the treatment of P. vivax malaria, either alone as second-line treatment or in combination with other active therapies.