*Rate per 100,000 population based on the U.S. Census Bureau’s
Shigellosis is a bacterial disease transmitted by the fecal-oral route, usually through hands contaminated with feces. It can also be transmitted through contaminated food and water or through oral-anal sex practices. Shigellosis is highly communicable, as only 10-100 organisms must be ingested to establish infection. Shigella bacteria infect only humans.
In 2004, 261 cases of shigellosis were reported in Indiana, for a case rate of 4.18 per 100,000 population (Table 1). This represents an increase from the incidence rate in 2003 (3.20). Figure 1 shows the number of reported cases per year for 2000-2004. The incidence of shigellosis peaked during the late winter and late spring months (Figure 2). As shown in Figure 3, age-specific rates were highest among preschoolers aged 1-4 years (20.61), followed by children aged 5-9 years (17.38), and adolescents aged 10-19 years (3.19). Females (4.54) were more likely to be reported than males (3.81). The rate of illness among blacks (14.77) was over seven times higher than the rate for whites (2.08) and five times the rate for other races (2.51).
The incidence rates were highest among the following counties reporting five or more cases:
Marion (19.5), Vanderburgh (15.0), Johnson (10.3), and Dearborn (10.3). Figure 4 shows Indiana counties reporting five or more cases.
In 2004, the serotype was determined for 243 (93%) of the 261 reported shigellosis cases. Shigella sonnei accounted for 229 (94%) of the serotyped cases. Thirteen cases were serotyped as Shigella flexneri, and one case was serotyped as Shigella boydii. There were no reported cases of Shigella dysenteriae in 2004.
Three outbreaks of shigellosis were reported in 2004 in Indiana.
The first outbreak of shigellosis was reported in Vanderburgh County. At least 30 attendees of a childcare facility met the case definition of shigellosis, and 10 tested positive for Shigella sonnei. One staff member of the daycare developed symptoms consistent with shigellosis, and seven secondary cases arose in household contacts. Infection was likely introduced through an ill child or staff member who attended the daycare. Any child or staff member testing positive for shigellosis was immediately excluded until five days of antibiotic therapy were completed or two negative stool specimens were submitted. A representative from the local health department made frequent visits to the facility to inspect conditions of the restrooms, diaper-changing areas, and common surfaces and objects. Prevention measures, such as hand-washing, glove use during diaper changes, and proper disinfection of surfaces and toys, were also implemented.
The second outbreak of shigellosis was reported in western Boone County. At least seven confirmed cases of Shigella sonnei were identified. Five of the seven cases attended a church daycare center, and three attended a local elementary school in Lebanon. Symptoms occurring included watery diarrhea, low-grade fever, headache, and nausea. Prevention measures, such as hand washing, glove use during diaper changes, and proper disinfection of surfaces and toys, were implemented.
The third outbreak of shigellosis was reported in Putnam County. Eight confirmed cases of Shigella sonnei were associated with an elementary school (six children and two adults). In addition, 26 other individuals having symptoms of shigellosis were identified but not laboratory confirmed. Infection was likely introduced through an ill child or staff member who attended the elementary school. The local health officer closed the kindergarten and first grade classes to prevent possible further transmission. In addition, any child or staff member testing positive for shigellosis was immediately excluded until five days of antibiotic therapy were completed or two negative stool specimens were submitted. The local health department provided recommendations to school officials for prevention, including exclusion policies and hand-washing guidelines. Parents of children attending the school were provided information regarding identification of symptoms, testing procedures, and control measures for shigellosis.