Data are presented resulting from examinations of stools from natives at Tela, Honduras, Port Limon, Costa Rica, and Santa Marta, Colombia. The incidence of infection with Trichomonas hominis was 20.6 per cent, with Chilomastix mesnili, 7.7 per cent, and with Giardia lamblia, 2.1 per cent.
The high incidence of infection with Trichomonas and Chilomastix may be accounted for (1) by the high temperature and moist climate that exists in Tropical America and are favorable for the transmission of these flagellates, (2) by the unsanitary habits of the natives which also favor transmission, and (3) by the character of the diet of the general population which is largely vegetable. In previous publications the writer has shown that these flagellates grow and multiply rapidly in hosts that live on a vegetable diet and are largely eliminated from hosts that live on a meat diet.
A comparison of the original results recorded in this paper with those published during the World War; and those reported by Jepps (1923) from the Federated Malay States and Boeck and Stiles (1923) from the United States indicates that there is a definite relation among human beings between a meat diet and the incidence of infection with these flagellates, especially with Trichomonas hominis.