Shigellosis, 2015

In 2015, 292 culture-confirmed cases of shigellosis (5.3 per 100,000 population) were reported (Figure 3). This represents a 314% increase from the 93 cases reported in 2014, and is 254% greater than the median annual number of cases reported during 2005- 2014 (median, 115 per year; range, 66 to 391). This is consistent with cyclical increases in shigellosis incidence that are observed every 4-7 years. S. sonnei accounted for 254 (87%) cases, and S. flexneri for 37 (13%) cases. The species was not identified in 1 case. There were no S. dysenteriae infections reported in 2015. Cases ranged in age from 3 months to 85 years (median, 17 years). Thirty percent of cases were ≤5 years of age; 49% of cases were 18 years of age or older. Fifty-two percent of cases were female. Sixty-three (22%) cases were hospitalized. No cases died. Fifty-two percent of cases reported either non-White race (119 of 263 cases) or Hispanic ethnicity (37 of 271 cases). Of the 268 cases for which travel information was available, 10 (4%) traveled internationally (7 of 236 [3%] S. sonnei, and 3 of 31 [10%] S. flexneri). Eighty-four percent of cases resided in the metropolitan area, including 54% in Hennepin County and 11% in Ramsey County.

Forty-one (14%) cases were part of 19 Shigella outbreaks identified in 2015 (median, 1 case per outbreak; range 1 to 10). Eighteen person-to-person outbreaks were caused by S. sonnei: 13 outbreaks were in daycares, 3 in schools, 1 in a homeless shelter, and 1 in an adult foster care facility. One confirmed foodborne outbreak of S. sonnei infections was associated with a private gathering; the vehicle of transmission was not determined.

In 2015, 43 of the 289 Shigella isolates received at MDH were tested for antimicrobial resistance. Of the 43 isolates, 44% (19 isolates) were resistant to trimethoprimsulfamethoxazole, 14% (6 isolates) were resistant to ampicillin, and 2% (1 isolate) had decreased susceptibility to azithromycin.

• For up to date information see>> Shigellosis (Shigella)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2015