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.