During 2000, 904 culture-confirmed cases of Shigella infection were reported (18.4 per 100,000 population). This represents the largest number of Shigella cases ever reported in Minnesota and a 256% increase from the 254 cases reported in 1999 (Figure 2).
In 2000, Shigella sonnei accounted for 880 (97%) cases, S. flexneri for 21 (2%) cases, and S. boydii for one (<1%) case (two isolates were not serotyped). Cases ranged in age from 8 days to 87 years, with a median of 8 years. The majority (57%) of cases were less than 10 years of age; children less than 5 years of age accounted for 32% of cases. One hundred three (11%) cases were hospitalized; one death was reported. Eighty-five percent of all Shigella cases resided in the Twin Cities metropolitan area, including 35% in Hennepin County and 24% in Anoka County.
Forty outbreaks of shigellosis were identified in 2000; all were due to S. sonnei. These outbreaks resulted in at least 641 illnesses, including 338 culture-confirmed cases (representing 38% of reported S. sonnei cases). The outbreaks occurred in a variety of settings, including daycare facilities (24 outbreaks), elementary schools (12 outbreaks), swimming beaches (two outbreaks), a restaurant (one outbreak), and an employee picnic (one outbreak).
Every tenth isolate of Shigella received at MDH was tested for antimicrobial resistance, but only one isolate was included from each outbreak. Of 80 isolates tested in 2000, 75 (94%) were resistant to ampicillin, eight (10%) were resistant to trimethoprim-sulfamethoxazole, and five (6%) were resistant to both of these drugs.