“To those who have become ill after eating at one of our cafes, we are deeply sorry,” Tropical Smoothie Cafe said in a statement. “We hope you recover quickly and completely.”

Symptoms can take up to 50 days to appear, so more cases could still be reported. Thus far, 70 of the infected customers were in Virginia, 10 were in Maryland, five in West Virginia, and one apiece were in New York, North Carolina, Wisconsin and Oregon.

The C.D.C. traced the infection to frozen strawberries imported from Egypt, and said it was not aware of other restaurants that may have received infected strawberries. Tropical Smoothie Cafe said it had switched to another supplier for all its restaurants nationwide, and would use only strawberries sourced from the Americas.

The Food and Drug Administration said in a statement that it would increase surveillance of imported strawberries.

Hepatitis A is a liver disease that ranges in severity from a mild illness that lasts weeks to a severe illness that lasts several months, according to the F.D.A. It is typically spread by ingesting fecal matter from contact with objects, food or drinks contaminated by an infected person. Symptoms include fatigue, abdominal pain, jaundice, abnormal liver tests, dark urine and pale stool.