State health officials said they will know Monday or Tuesday whether the latest cases, involving an unspecified number of high school students, are the first secondary cases tied to the largest known hepatitis A outbreak, which was confirmed last month at a Chi-Chi's restaurant about 25 miles northwest of Pittsburgh.
Health officials have confirmed 640 people -- including three who died -- got hepatitis A from eating or working at the restaurant, but have yet to confirm any secondary cases in which those infected spread the disease to others.
The high school where some students tested positive for hepatitis A in the past week is about 10 miles from the restaurant.
"When new cases come in and certainly because they're in the same area, you want to talk to people and find out what you can," Richard McGarvey, a Pennsylvania Health Department spokesman, said Saturday.
The South Side Area School District has sent a letter to parents informing them that some students have hepatitis A. The district also enacted some temporary health guidelines, including requiring that all food brought to schools be sealed and store-bought.
District officials did not immediately return calls for comment Saturday.