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Public Health - Seattle & King County

Shigellosis

Shigellosis is an enteric bacterial infection caused by Shigella species, most commonly S. sonnei and S. flexneri. The organism is spread through the fecal-oral route and humans are the only known host. Food and water contaminated with human fecal matter are common vehicles of transmission. Because the infective dose of Shigella bacteria is very low, this infection is easily transmitted via household or sexual contact. Travelers to developing countries with poor sanitation are also at risk for infection.

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Shigellosis in King County

Purpose of surveillance:

  • To identify common source outbreaks
  • To identify and eliminate sources of transmission including contaminated food and water
  • To identify and eliminate person-to-person spread of infection

Shigellosis Case Data in King County

Local epidemiology:

Forty-seven cases of shigellosis were reported in 2013; no outbreaks were identified. Seventy-nine percent of the cases were in males; nine (19%) of the cases were in children under age 18. Ten (21%) of the cases required hospitalization, none died.

Shigella sonnei and S. flexneri accounted for 23 and 19 cases, respectively; one case of S. dysenteriae was reported. Serotype data were not available for four cases. Fourteen cases reported international travel during their exposure periods, including travel to Mexico (6), Africa (4), Asia (2), South and Central America (1), and the Middle East (1).

Nineteen (40%) of the cases reported in 2013 occurred among men who have sex with men, 16 of whom were known to be HIV-positive. Both the number and proportion of shigellosis cases that have been HIV+ have increased in recent years. Many of these cases denied sexual contact during their exposure period, or reported only one long-term partner without symptoms of illness. Seattle and other cities in the United States have reported past outbreaks of shigellosis among men who have sex with men.

Each year in Washington state 115 and 185 shigellosis cases are reported.