Studies on Malarial Parasites. V. Effects of Ascorbic Acid on Malaria ( Plasmodium knowlesi ) in Monkeys. ∗

Conclusions and Summary

1. Plasma and whole blood ascorbic acid levels were significantly lower in parasitized monkeys than in normal animals.

2. There was an abnormal course of parasitemia in 7 of our monkeys which showed spontaneous ascorbic acid deficiency and in 2 other animals which were made ascorbic acid deficient by removing the vitamin from their diet.

3. Following the administration of the pure ascorbic acid, there was a normal course of parasitemia in one of the monkeys spontaneously ascorbic acid deficient and in those made ascorbic acid deficient by dietary means.

Withholding ascorbic acid therapy for more than 7 days appeared to give the spontaneously deficient monkeys time to produce an immunity and to control the infections. If ascorbic acid treatment was withheld from the animals made vitamin C deficient there was a prolongation of the course of infection but eventually the parasitemia overwhelmed the animal.