The Montgomery County Department of Health has warned parents to look out for symptoms of whooping cough, also known as pertussis, after an outbreak at Bridle Path Elementary School in Lansdale.

"The first two cases were before Thanksgiving and the last five cases were reported just this week," said Harriet Morton, spokeswoman for the health department.

"The symptoms begin with a minor respiratory infection, like the common cold," said Morton. "But if within two weeks the cough becomes more severe and you hear a 'whoop', the child should be taken to the doctor immediately."

The seven children reported as having pertussis are being treated with antibiotics. If left untreated, pertussis can cause pneumonia, ear infections, dehydration, seizures and even death.

Montgomery County has seen 12 reported cases of pertussis this year, down from 38 last year. Bridle Path Elementary is in the North Penn district.

- Samantha Shepard