Since the mid-1980s, the epidemiology of invasive group A streptococcal (GAS) infections in the United States and worldwide has changed, and the incidence of invasive infections, streptococcal toxic shock syndrome (strep TSS), and necrotizing fasciitis has increased. These changes may be the result of a shift in GAS M-types and a corresponding increase in strains that produce certain pyrogenic exotoxins. Recognizing the importance of monitoring changes in the occurrence of severe group A streptococcal disease, the Council of State and Territorial Epidemiologists recommended in April 1995 that invasive GAS infections and strep TSS be added to the National Public Health Surveillance System.

Most invasive GAS infections occur sporadically and are acquired in the community. For these cases, preventing illness and death depends on improving recognition and treatment. Primary prevention of invasive GAS disease may be more feasible for infections that are acquired in institutions (such as hospitals and nursing homes) and for secondary cases that occur among contacts of persons with invasive disease. Most nosocomial infections (for example, wound infections, postpartum endometritis, and sepsis) occur in surgical or obstetric settings, or are associated with intravenous catheters. Secondary invasive disease in the community is uncommon, although studies of household contacts of those with GAS infectionshave found a substantially increased risk for infection in this group. GAS infections spread easily from person to person after contact with respiratory secretions of an infected person and have traditionally caused epidemics of pharyngitis, scarlet fever, and rheumatic fever. Recently, clusters of invasive infections have been reported in families, hospitals, and nursing homes; community-wide outbreaks have also been reported.

As state health departments initiate surveillance for invasive GAS disease and strep TSS, guidelines for prevention will help in interpreting these data and in formulating a public health response. CDC convened a meeting of experts from academia and public health (October 10-11, 1995), to discuss existing data and strategies for preventing invasive GAS disease in institutions and the community. Discussions centered on the magnitude of risk for secondary disease among close contacts of persons with invasive infection and the potential for preventing disease by chemoprophylaxis, and on approaches for investigating and preventing infections in institutions. Recommendations are being developed, and the conclusions of the participants will be presented at a later date.

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