Effect of Vitamin A Deficiency on Susceptibility of Rats to Angiostrongylus cantonensis 1

Summary

The effect of vitamin A deficiency on susceptibility to infection by A. cantonensis was studied using rats reared by a procedure enabling the synchronous induction of vitamin A deficiency and the stringent control of both dietary protein and energy input. Vitamin A-deficient (A^-) rats were more susceptible to infection by third-stage larvae than (A⁺) controls, as revealed from mortality rate, survival period, and/or worm recovery. Evidence was presented to show that more larvae were able to penetrate the intestinal mucosa of A^- rats than that of A⁺ controls, a finding that is consistent with the fact that one of the functions of vitamin A is to maintain the morphological and functional integrity of the mucosa. Moreover, following a primary infection A^- rats developed a lower degree of protective immunity than A⁺ control. Animals that were initially exposed to the parasite during the A⁺ state had a longer survival period and a lower worm burden than the group that was deficient in vitamin A during the early period of initial infection.