2005 - Shigellosis

Table 1. Shigellosis Cases by Race and Sex, Indiana, 2005

  2005 2001-2005
Cases Rate* Cases
Total 195 3.11 1,047
Race
   White 58 1.04 434
   Black 78 14.05 325
   Other 7 4.29 31
   Not Reported 52 - 257
Sex
   Male 82 2.66 455
   Female 113 3.55 591
   Not Reported 0 - 1
*Rate per 100,000 population based on the U.S. Census Bureau’s population data as of July 1, 2005

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 2005, 195 cases of shigellosis were reported in Indiana, for a case rate of 3.11 per 100,000 population (Table 1). This represents a decrease from the incidence rate in 2004 (4.18). Figure 1 shows the number of reported cases per year for 2001-2005. The incidence of shigellosis peaked during the late summer (Figure 2). As shown in Figure 3, age-specific rates were highest among preschoolers aged 1-4 years (15.39), followed by children aged 5-9 years (13.01), and infants less than 1 year of age (4.65). Females (3.55) were more likely to be reported than males (2.66). The rate of illness among blacks (14.05) was over 13 times higher than the rate for whites (1.04) and 3 times the rate for other races (4.29); however, 52 cases (27%) did not report race data.

The incidence rates were highest among the following counties reporting five or more cases:
Marion (12.9), Lawrence (12.9), Tippecanoe (5.2), and Johnson (3.9). Figure 4 shows Indiana counties reporting five or more cases.

In 2005, the serotype was determined for 173 (89%) of the 195 reported shigellosis cases. Shigella sonnei accounted for 153 (88%) of the serotyped cases. Nineteen cases were serotyped as Shigella flexneri, and one case was serotyped as Shigella dysenteriae. There were no reported cases of Shigella boydii in 2005.

There were no reported outbreaks of shigellosis in Indiana in 2005.