According to local press reports, the DuPage County Health Department is staffing its call center throughout the weekend to keep tabs on the rising number of gastrointestinal illnesses being reported from a Subway restaurant in Lombard.

Four more cases of shigellosis were confirmed Friday, bringing the total number of confirmed cases caused by the outbreak at the restaurant to 12, health department spokesman Dave Hass said. Of those 12 cases, seven have required hospitalization. Six of those who were hospitalized have been released, Hass said.

The restaurant at 1009 E. Roosevelt Road in Lombard remains closed as investigators try to determine the cause of the outbreak. Hass said the restaurant would open sometime next week at the earliest. Anyone who ate at the restaurant between Feb. 24 and March 1 and became ill within 12 hours to four days afterward is asked to report the incident to the health department by calling (630) 682-7400.

Shigella is a family of bacteria that can cause sudden and severe diarrhea (gastroenteritis) in humans. Shigellosis – the illness caused by the ingestion of Shigella bacteria – is also known as bacillary dysentery. It can occur after ingestion of fewer than 100 bacteria (American Public Health Association [APHA], 2000), making Shigella one of the most communicable and severe forms of the bacterial-induced diarrheas (Gomez et al., 2002). Shigella thrives in the human intestine and is commonly spread both through food and by person-to-person contact. It is named after Kiyoshi Shiga, a Japanese scientist who discovered Shigella dysenteriae type 1 in 1896 during a large epidemic of dysentery in Japan (Keusch & Acheson, 1996).

The number of shigellosis cases reported annually to the Centers for Disease Control and Prevention (CDC) has varied over the past several years, from more than 17,000 during 1978–2003, to an all-time low of 14,000 in 2004, to almost 20,000 in 2007 (CDC, 2009b). Many cases go undiagnosed and/or unreported, however. The CDC estimates that 450,000 total cases of shigellosis occur in the U.S. every year (Baer et al., 1999; CDC, 2009a). Shigellosis is also characterized by seasonality, with the largest percentage of reported isolates occurring between July and October and the smallest proportion occurring in January, February, and March (Gupta et al., 2004).