Primary interest: zoonotic infections caused by helminths; secondary interest: zoonoses caused by other organisms. Investigations conducted without interruption since 1949 (mainly in Alaska, NE Siberia, China and South America) have concerned cestodes of the genus Echinococcus; E.granulosus (Batsch, 1786); E.oligarthrus (Diesing, 1863); E.multilocularis Leuckart, 1863 and E.vogeli Rausch et Bernstein (1972) each of which causes a specific form of hydatid disease in man. Main emphasis has been placed on E.multilocularis, the cause of alveolar hydatid disease, a cancer-like disease of the human liver, on St. Lawrence Island Bering Sea. Intensive epidemiological studies have been conducted there, and major effort has been directed subsequently toward diagnosis, treatment (including chemotherapy), and prevention of AHD. These investigation, as well as those concerning other helminths, also have involved taxonony and elucidation of cycles. Another major project concerns fish-transmitted helminths, primarily cestodes of the genus Diphyllobothrium. Fundamental studies involving other helminths are undertaken as time permits.