ABSTRACT
I. BACKGROUND The genus Streptococcus includes some of the most important organisms encountered in medicine and in the food industry (1). A small number of species cause disease in humans, some are associated with disease in animals, and a few have been domesticated for use in culture of yogurt, buttermilk, and certain cheeses. While no longer a major cause of foodborne illness, streptococci were among the first to be recognized as pathogens transmitted by milk and prepared foodstuffs. Widespread milkborne epidemics of scarlet fever and "septic sore throat" occurred in England in the late nineteenth century and in the United States in 1911-1915 (2,3). In the Baltimore epidemic of 1911, children especially were afflicted by disease of unusual severity with marked enlargement of cervical lymph nodes, as beautifully illustrated in a figure from Hamburger's report (Fig. 1) (4). Investigations of major epidemics in Norway (5), Boston (6), and Chicago (7) established an unequivocal association between streptococci and milk (8,9). These and later outbreaks were responsible for prompting major improvements in the dairy industry, especially the growing use and popular acceptance of pasteurization (10-13). There have been no large-scale milkborne epidemics in the last halfcentury, but streptococci continue to cause sporadic outbreaks of food-associated illnesses. Current estimates, extrapolated from surveillance data from the U.S. Centers for Disease Control and Prevention (CDC), suggest that streptococci may account for about 50,000 cases of foodborne disease per year in the United States, about 0.4% of all cases of food-related illness (14).
