Shigellosis in the United States: Ten-year Review of Nationwide Surveillance, 1964-1973

In the 10 years 1964-1973, 105,832 isolations of shigellae were reported to the Center for Disease Control through a nationwide surveillance system. The number reported increased by approximately 13% annually, from 5852 in 1964, when only 17 centers reported all 4 quarters; to 16,797 in 1973, when 52 centers reported each quarter. The rate of reported isolations varied from 4.6 per 100,000 persons in 1965 to 9.1 per 100,000 in 1973. Shigella sonnei accounted for 64% of all these isolates and for more than 80% of isolates in 1973. The majority of reported cases of shigellosis occurred in young children and in women of childbearing age. During the 10-year surveillance period, 35 epidemics in 25 states were investigated. Two-thirds of these outbreaks were the result of person-to-person spread; investigations of common-source outbreaks showed the importance of both water and foodstuffs, especially salads, as potential vehicles of contamination. Indian reservations, custodial institutions, and day-care centers were identified as special high-risk settings for the transmission of shigellosis. The emergence of R-factor-mediated antimicrobial-resistance patterns in recent years has necessitated antibiotic sensitivity testing to determine the drug of choice for treatment of individual cases. Initial testing of oral vaccines suggests these vaccines will have only limited usefulness in protecting certain high-risk populations. Public health education coupled with improvements in water and sewerage systems remains the most satisfactory means of control.