Rebecca Campbell, the school nurse at Western Harnett High School alerted parents to the outbreak.
According to an announcement sent out Monday night, there are several confirmed cases of the highly contagious infection.
Students who have been directly exposed in class or on the school bus were sent home with a letter explaining what steps to take if they develop symptoms, which include a deep cough which could last for weeks or months.
The illness is most dangerous for small children or those with weakened immune symptoms.
Concerned Harnett County residents should contact their physicians or the county health department at (910) 893-7550.