The effect of paraminobenzoic acid, parahydroxybenzoic acid and riboflavin on Plasmodium gallinaceum in chicks

Abstract

1. (1) Plasmodium gallinaceum developed at a subnormal rate in chicks fed on a purified basal diet which was deficient in paraminobenzoic acid and parahydroxybenzoic acid. 2. (2) The addition of either paraminobenzoic acid or parahydroxybenzoic acid to the basal diet in low concentrations (0.005 per cent.) produced an increase in parasitaemia. Higher concentrations (0.1 – 0.5 per cent.) of paraminobenzoic acid resulted in an infection lower than that of the chicks fed on the basal diet, whereas high concentrations of parahydroxybenzoic acid had no suppressive effect. 3. (3) Parahydroxybenzoic acid in low or high concentration antagonized the suppressive effect of high concentrations of paraminobenzoic acid. 4. (4) Chicks fed on a diet deficient in riboflavin developed a markedly lower parasitaemia than did those chicks fed on a diet rich in this substance. 5. (5) These experiments indicate that small amounts of riboflavin, paraminobenzoic acid and parahydroxybenzoic acid are required in the diet of chicks, to allow P. gallinaceum to develop normally. Large amounts of paraminobenzoic acid are inhibitory to the parasite, possibly because they interfere with the utilization of parahydroxybenzoic acid.