Montgomery County health officials said Thursday that they have confirmed two new cases of whooping cough among Montgomery County students, bringing the total number to 14 since an outbreak was first reported last week.

All but one of the cases have been linked to exposure at a summer camp in Pennsylvania, said Mary Anderson, spokeswoman for the county’s Department of Health and Human Services.

The two new cases involve students at Thomas S. Wootton High School in Rockville and Sherwood High School in Sandy Spring. Health department and school officials said they were sending letters home to parents to advise them to watch for signs of the illness.

“We want to make sure parents are informed what to look for, should their children start to exhibit symptoms,” said Dana Tofig, Montgomery schools spokesman.

Whooping cough, or pertussis, is highly contagious and begins with cold-like symptoms, including coughs and runny noses, but can lead to severe coughing fits. The illness is most dangerous in infants, but complications can include pneumonia and encephalitis.

Public health officials strongly urge parents to have their children vaccinated as infants, and a booster is recommended at age 11 or 12.

Montgomery health officials said Thursday that the 12 cases they had previously reported — all considered confirmed cases, they said — included both public and private school students in Montgomery. In addition to Wootton and Sherwood, the public schools are Robert Frost Middle, Julius West Middle, Cabin John Middle and Cold Spring Elementary.

No information was available about private schools, officials said.