A second case of mumps at Abington Senior High School -- again affecting a student -- has been confirmed, principal Angelo Berrios said in a letter to parents Friday.

The discovery, two days after the first, has led the Montgomery County Office of Public Health to investigate the cases as an outbreak of the viral infection.

The first case affected an age-appropriately vaccinated student, Berrios said. He did not release details about the second student.

The infection is characterized by fever, swelling, and tenderness of one or more salivary glands. An infected person can transmit mumps through saliva.

In consultation with the Pennsylvania Department of Health, the county Health Department is recommending that students, teachers, and support staff who have had one dose of a mumps-containing vaccine and are considered to be immune receive a second dose, according to the Berrios letter. Those who are not immune and have never received a mumps-containing vaccine should stay home until they are vaccinated or through June 12, the school district said. The MMR (measles, mumps, and rubella) vaccine is recommended for children between 12 and 15 months of age, with a second dose between 4 and 6 years of age.

People experiencing mumps-like symptoms should contact their primary-care physician.