Trends in the incidence and transmission patterns of trichinosis in humans in the United States: comparisons of the periods 1975-1981 and 1982-1986.

Since 1947, the U.S. Public Health Service has recorded statistics on reported cases of trichinosis in humans. More complete clinical and epidemiologic data on cases became available after 1965, when trichinosis was officially made a notifiable disease. The numbers of reported cases declined markedly from an average of approximately 400, with 10-15 deaths reported each year in the late 1940s, to 57 per year, with three deaths in the 5 years 1982-1986. Although annual incidence was highest in sparsely populated Alaska, the highest numbers of cases are reported from the northeastern United States. Food sources of this infection vary in different geographic regions. The decline in annual incidence during the past 12 years appears to be accounted for largely by a decline in the number of cases attributed to commercially purchased pork, although pork products continue to be the major source of infections in humans. The number of cases due to ingestion of wild animal meat have remained relatively constant. Activities at the national and state level that have improved the prospects for control and prevention of trichinosis in commercial products are discussed.