Hundreds of patients in Chicago-area hospitals, including children, are at risk for tuberculosis after a doctor-in-training tested positive for the disease.

Patients at Northwestern Memorial Hospital, Prentice Women's Hospital, Children's Memorial Hospital and Evanston Hospital were exposed to TB between November of last year and April of this year.

The health care worker was a 26-year-old female resident in Northwestern's training program who had rotated through the other three hospitals.

Hundreds have been exposed. At Children's Memorial alone, it is estimated that approximately 150 children and 300 employees were exposed. So far, no one, including the resident's family members, has tested positive for the disease.

Northwestern says it's contacting 17 patients who may have been affected and is evaluating another 100 who may have received care from the worker.