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Current Trends Shigellosis -- United States, 1981

In 1981, 15,006 Shigella isolations from humans were reported to CDC. While this represented a 6% increase over the 14,168 isolates reported in 1980, it remained 2% below the 15,334 reported during the peak year, 1978 (Figure 4).

Shigella serotypes were reported for 14,278 of the 15,006 isolates and were distributed by serotype as follows: S. sonnei --9,423 (66%), S. flexneri --4,141 (29%), S. boydii --510 (3.6%), and S. dysenteriae --204 (1.4%). When compared with 1980, this represented increases of 46% for S. boydii, 39% for S. dysenteriae, and 9% for S. sonnei, and a decrease of 5% for S. flexneri. The increases were not confined to one state or region. From 1980 to 1981 S. sonnei increased notably in Connecticut (67 to 337), Missouri (50 to 128), Virginia (83 to 889), and Washington (161 to 307); S. boydii increased in Texas (43 to 82).

The reported age distribution* of persons from whom isolates were obtained is shown in Figure 5. The rate, highest for 2-year-old children, decreased abruptly for older children and decreased more gradually for adults, except for a slight increase for 20-29 year-olds. Although in the 20-29-year age group a slightly higher isolation rate was reported for women, the isolation rates by sex were similar. The median ages in years of persons from whom isolates were reported were S. boydii--9.0, S. dysenteriae--16.5, S. flexneri--10.0, and S. sonnei--6.0. *Age, sex, and type of residence were unavailable for California.

Since shigellosis is a more significant problem for some population groups than for others, data were tabulated separately for patients residing in certain institutions (e.g., nursing homes, facilities for the mentally ill, and other resident-care centers), and on American Indian reservations. Twenty-nine percent of the reports included data on patient residence at the time of illness onset: 0.9% lived in institutions and 1.5% on Indian reservations. Seventy-four percent of the reported isolates from residents of institutions were S. flexneri, and 26% were S. sonnei. Similarly, 69% of the isolates from residents of Indian reservations were S. flexneri, and 31% were S. sonnei. This contrasts with the remainder of Shigella cases with known residence in which S. sonnei represented 75% of isolates and S. flexneri represented 22.5%. Reported by Statistical Svcs Activity, Enteric Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: This report is based on CDC's Shigella Surveillance Activity, a passive, laboratory-based system that receives reports from the 50 states and the District of Columbia. These reports do not distinguish between clinical or sub-clinical infections or between chronic or convalescent carriers.

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