The Maine Center for Disease Control and Prevention has confirmed a fourth case of pertussis at Yarmouth High School, bringing the total number of confirmed whooping cough cases in Yarmouth public schools this month to five.

Superintendent Andrew R. Dolloff sent an email Wednesday notifying parents about the spread of the illness. A case of pertussis was also reported earlier this month at Yarmouth Elementary School.

Dolloff said that custodians have been instructed to thoroughly disinfect all fixtures, faucets and fountains on a daily basis.

Pertussis is an illness that is spread from person to person through coughing and sneezing. Pertussis usually begins with the same symptoms of a common cold (sneezing, runny nose, low grade fever and a cough) and can develop into a severe cough after a few weeks. Most children are vaccinated, but it is still possible for vaccinated children to become ill.

Pertussis, or whooping cough, is spread from person to person through the air. A person has to breathe in droplets from an infected person to get sick. Pertussis can be treated with antibiotics.