Notes from the Field: Typhoid Fever Outbreak Associated with an Asymptomatic Carrier at a Restaurant – Weld County, Colorado, 2015

On September 11, 2015, a single case of typhoid fever, caused by Salmonella Typhi infection, was reported to the Colorado Department of Public Health and Environment (CDPHE). Because the patient (patient A) had symptom onset September 2 and had traveled internationally for 4 days 60 days before symptom onset, the case initially was thought to be travel-associated* (1,2). On October 1, a second case of S. Typhi infection was reported in patient B, with symptom onset September 20. Patient B reported no international travel or contact with ill persons or known carriers. Patients A and B resided approximately 6 miles (10 kilometers) apart and had no discernible epidemiologic connection. Family members of patients A and B tested negative for S. Typhi. CDPHE and the Weld County Department of Public Health and Environment (WCDPHE) investigated to 1) determine whether these cases represented a larger outbreak, 2) identify common exposure sources, and 3) stop transmission. Investigators determined that the typhoid fever in both patients and in a third patient (patient C) was associated with eating in the same restaurant during a 5-day period.