Three types of influenza viruses are recognized: A, B and C.

Influenza is an acute viral disease and is characterized by fever, headache, myalgia (muscle ache), sore throat and cough. The cough can be severe and protracted. Other manifestations are self-limited in most people, with recovery in 2 to 7 days. Influenza may be clinically indistinguishable from disease caused by other respiratory viruses, such as common cold, croup, bronchitis, viral pneumonia and undifferentiated acute respiratory disease. GI tract manifestations (nausea, vomiting and diarrhea) are uncommon but may accompany the respiratory phase in children and have been reported in 25% of children in school outbreaks of influenza.

Signs and symptoms occur anywhere from 1 to 3 days following exposure.

Transmission of influenza is airborne. It is predominately spread among crowded populations in enclosed spaces. The influenza virus may persist for hours, particularly in the cold and in low humidity, and transmission may also occur through direct contact. New subtypes may be transmitted globally within 3 to 6 months.

Influenza is communicable for 3 to 5 days from clinical onset in adults and up to 7 days in young children.

• Education in basic personal hygiene, especially transmission via unprotected coughs and sneezes, and from hand to mucous membrane
• Use tissues when sneezing/coughing, sneezing/coughing in your sleeve when tissues unavailable, wash hands after sneezing/coughing
• Use of hand sanitizers when unable to wash hands
• Immunization with available inactivated and live virus vaccine may provide 70%-80% protection

Students/staff should be excluded from school for any of the following reasons: an elevated temperature, student too ill or uncomfortable to participate in classroom, excessive, productive coughing or when student appears to be contagious to others. A healthcare provider’s note is not required to return to school.