THE interesting discovery by Dr. Louis Sambon that pellagra is due to a protozoal parasite conveyed by flies of the genus Simulium (NATURE, October 27) is, we may presume, merely the prelude to an ...

World Health Org. Tech. Rep. Ser. No. 87, 20 (1954). Crisp, G., “Simulium Onchocerciasis in the Northern Territories of the Gold Coast”, 152 (H. K. Lewis for Brit ...