Among Travelers Please see the Destinations section for recommendations for specific countries. 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 can have fever, cough, sore throat, fatigue, muscle aches, headaches, runny nose, and watery eyes.
Children can also experience vomiting and diarrhea.
Some older persons might not have fevers. Although the fever and body aches usually last for 3 to 5 days, a cough and fatigue can persist for 2 weeks or more. Both strains are similar to the strains contained in the 2000-2001 influenza vaccine. In an average year in the United States, more than 100,000 persons are hospitalized and more than 20,000 deaths are related to influenza. In the tropics, influenza can occur throughout the year.