Field evaluation of primaquine in the control of Plasmodium vivax.

Two regimens of primaquine in combination with amodiaquine have been compared with amodiaquine alone in known cases of Plasmodium vivax in an endemic area of El Salvador, C.A. A 5-day regimen of primaquine, with dosages based on an adult dose of 15 mg per day, produced a substantial reduction in the numbers of patients experiencing renewed parasite activity and in the number of parasitemias experienced by the group during 9 mo of posttreatment observation, when compared with patients treated only with amodiaquine. A single dose regimen, based on an adult dose of 45 mg, similarly reduced the number of patients with renewed parasite activity and the number of parasitemias in the group. Those patients who experienced malaria attacks subsequent to treatment with either primaquine regimen experienced fewer such attacks than did those receiving amodiaquine alone. It is concluded that such primaquine regimens, which are more practicable for field use than the full 14-days curative regimen, are of value to both the patient and the community through the reduction of parasite episodes and the reduction of the source of mosquito infection for continuation of transmission.