Expanding the Horizons of Foodborne Listeriosis

A little over 10 years ago, infections caused by the gram-positive coccobacillus Listeria monocytogenes were rare events, providing grist to the mill of grand rounds at university medical centers and case reports to medical journals. 1 Small clusters of temporally related neonatal infections occasionally piqued the curiosity of epidemiologists from the Centers for Disease Control and others, 2,3 but investigations of these clusters shed little light on the transmission of this pathogen. Investigators were stymied by the small number of cases in each cluster, and at the Centers for Disease Control, listeriosis came to be known as the "graveyard of epidemiology"! This situation changed radically in 1979 when a large outbreak of nosocomial listeriosis in Boston, Mass, city hospitals suggested the possibility of foodborne illness. 4 Foodborne transmission was finally confirmed by an outbreak of community-acquired perinatal and adult listeriosis traced to ingestion of contaminated cabbage from a farm on