In 2019 California public health officials investigated an outbreak of Salmonella Thompson infections associated with chicken served at an El Pollo Loco restaurant located at 2820 Lenwood Road in Barstow, California. A total of 34 cases of salmonellosis were reported from 6 states, including 21 cases in California. Five cases were hospitalized, and no deaths were reported. Illness onset dates ranged from July 18, 2019, through October 19, 2019.

On October 23, 2019, San Bernardino County Department of Public Health (SBCDPH) staff conducted an inspection at the restaurant. The inspection identified several out-of-compliance items and one major violation related to potentially hazardous food (salsa) being stored at an elevated temperature. The next day, California Department of Public Health staff and SBCDPH staff collected 75 environmental swabs and 5 raw chicken samples at the restaurant. Laboratory results confirmed that 13 environmental swabs and one chicken sample were positive for Salmonella Thompson. The positive environmental swabs were collected from various food contact and non-contact surfaces. Whole genome sequencing revealed that the environmental isolates and the chicken isolate were closely related to clinical isolates.

One employee tested positive for Salmonella Thompson. The employee's isolate was a WGS match to the outbreak strain.

Investigators concluded that inadequately trained employees may have resulted in cross-contamination and/or under-cooking of chicken as the reasons for this outbreak.

The outbreak was assigned CDC Cluster Code 1909MLJP6-1.