DIFFERENTIAL SENSITIVITY OF THE PREERYTHROCYTIC STAGES OF PLASMODIUM-CYNOMOLGI-B TO THE PROPHYLACTIC ACTION OF PRIMAQUINE

The sensitivity of the developing pre-erythrocytic stages of Plasmodium cynomolgi bastianelli to primaquine in single, two or three dose regimens administered at varying times during the incubation period has been investigated. The study reveals that the early pre-erythrocytic stages of the parasite are more susceptible to primaquine than the later stages. Regimens of 5.34 mg/kg x 1 dose on day 0 or day + 1; 2.67 mg/kg x 2 doses on days 0 and 1 and 1.78 mg/kg x 3 doses on days -1, 0, + 1 or days + 1, + 2, + 3 protected all the treated monkeys while identical regimens administered after day 3 of sporozoite inoculation were not curative.