Search

Nine fatal cases of canine American trypanosomiasis (Chagas' disease) were encountered from November, 1972, through November, 1975. Of the 9 cases, 7 occurred in dogs from 5 central Texas counties, and all but one case was diagnosed during the months of September, October, or November. The source of infection was discovered in only one case--that being a doghouse heavily infested with Triatoma lectularius occulta. Each of 6 bugs collected had infective forms of the protozoan, Trypanosoma cruzi. Trypanosomiasis usually is not considered in the differential clinical diagnosis of cardiac dysfunction in man or other mammals in the United States. An antemortem diagnosis was made in only 1 of the 9 dogs, with diagnosis in the remaining dogs being made at necropsy. The predominant microscopic lesion in all dogs was necrotizing granulomatous myocarditis associated with the amastigotes of T cruzi.

Rats on a vitamin A-deficient diet for 4 weeks showed a slight increase in susceptibility to Trypanosoma cruzi infection; however, pair-fed control rats were equally susceptible, suggesting that inanition was responsible for the lowered resistance. After 13 weeks on the vitamin A-deficient diet, rats were significantly more susceptible to T. cruzi infection than the pair-fed control rats. Spontaneous bacterial infection was observed in rats on the deficient diet and appeared to be a contributing cause of death in some of the inoculated rats.

1. 1. T. cruzi produced severer infections in pantothenate-deficient rats than in normal and inanition control groups of rats. Parasitemia was more marked and of longer duration and cardiac lesions were usually more extensive in the vitamin-deficient animals. 2. 2. The incidence of lung infections among pantothenate-deficient rats suggests this deficiency may increase the susceptibility of rats to spontaneous respiratory disease.

Albino rats maintained for 13 weeks on a riboflavin-deficient diet did not exhibit a significant increase in susceptibility to T. cruzi infection. The slight increase in severity of infection as evidenced by cardiac damage and parasitemia was attributed to inanition rather than to deficiency of the vitamin.