Primaquine as Prophylaxis for Malaria for Nonimmune Travelers: A Comparison with Mefloquine and Doxycycline

Abstract

Malaria prophylaxis for travelers is a controversial issue. The commonly used regimens are associated with side effects, low compliance, or low efficacy, which have raised concern regarding their use. In addition, they are inefficient against the tissue stage of the parasite and thus do not prevent relapses of Plasmodium vivax infection. Primaquine is aimed at the pre-erythrocytic stage and thus may be a potential causal-prophylactic treatment that can abolish the need for long postexposure therapy. During 1995-1998, we followed retrospectively travelers who joined rafting trips to an area in Ethiopia where both P. vivax and Plasmodium falciparum are hyperendemic. Of the 106 travelers who received primaquine, 5.7% developed malaria; of the 19 doxycycline recipients, 53% developed malaria; and of the 25 mefloquine recipients, 52% developed P. vivax malaria (>/=3 months after return from the area of endemicity). Primaquine was well tolerated, and only 1 withdrawal from therapy (due to gastrointestinal symptoms) was reported. Primaquine was shown to be a safe and effective prophylactic drug against both P. falciparum malaria and P. vivax malaria in travelers.

Primaquine revisited six decades after its discovery

“…Similarly, the paediatric doses can be increased from 0.25 to 0.5 mg/kg/d, according to the parasite strain that prevails at the site of exposure. The beginning of terminal prophylaxis with PQ should coincide with the last 2 weeks of prophylactic administration of schizontoxides doxycycline, mefloquine or chloroquine or with the final week of prophylaxis with atovaquone-proguanil [14,19,20].…”

Neglect of Plasmodium vivax malaria

“…Separating these issues has practical validity; however, one gets back to the issue of whether the presumptive therapy provides protection against relapsing vivax malaria in travelers. Schwartz and colleagues [75,76] looked at the effectiveness of various regimens of prophylaxis in Israeli travelers. Suppressive prophylaxis (the standards such as MQ or doxycycline) routinely failed to prevent late relapses of P. vivax, despite the prescribed use of PQ terminal prophylaxis.…”

Malaria Chemoprophylaxis for the International Traveler, Current Options and Future Possibilities

“…Primaquine is a well-tolerated medication with the most common side effects being nausea, vomiting, and abdominal cramps (Fryauff et al, 1995). It was shown to have better tolerability than chloroquine in Irian Jaya transmigrates, and in a retrospective study of travelers to Ethiopia it had favorable tolerability compared to mefloquine and doxycycline (Schwartz & Regev-Yochay, 1999;Baird et al, 2001). Severe hemolytic anemia can occur in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency and should be avoided in any patient with this enzymopathy.…”