The 1998-99 influenza season was relatively severe. Overall influenza activity in the United States began to increase in January and peaked in late February and early March.
Influenza is a highly contagious respiratory viral illness.
Influenza A and B are the major types of influenza viruses that cause human disease and affect persons of all ages. Persons with influenza may have fever, cough, sore throat, fatigue, muscle aches, headaches, runny nose, and watery eyes. Children may experience vomiting and diarrhea in addition to these symptoms. Some elderly persons may not have fevers. Although the fever and body aches usually last for 3-5 days, a cough and fatigue may persist for 2 weeks or more.