There are many different types, or strains, of the influenza virus, including the seasonal flu virus and the H1N1 influenza virus (commonly called swine flu).
Causes of the flu. The flu is caused by influenza virus types A, B, and C. Both type A and type B flu viruses are responsible for the seasonal outbreaks of flu. Type A flu viruses are found in many different animals, including ducks, chickens, pigs, and horses. Influenza B viruses circulate widely only among humans. 1 Influenza, commonly called the flu, is caused by viruses that infect the respiratory tract. 2  Symptoms include fever, chills, cough, sore throat, headache, muscle aches, and fatigue. 3  The incubation period for flu is about one to four days. Overview. The influenza virus, conversationally called the flu, is an illness that's highly contagious and causes a number of different symptoms. There are many different types, or strains, of the influenza virus, including the seasonal flu virus and the H1N1 influenza virus (commonly called swine flu). Although initially symptoms of influenza may mimic those of a cold, influenza is more debilitating with symptoms of fatigue, fever, and respiratory congestion. Colds can be caused by over 100 different virus types, but only influenza viruses (and subtypes) A, B, and C cause the flu. The flu is caused by influenza virus types A, B, and C. Both type A and type B flu viruses are responsible for the seasonal outbreaks of flu. Type A flu viruses are found in many different animals, including ducks, chickens, pigs, and horses. Influenza B viruses circulate widely only among humans. Other study findings indicated that the H7N9 virus did not cause severe disease in the ferrets and did not spread systemically to the spleen, kidney, liver, or intestinal tract. The lack of systemic spread by H7N9 is different from H5N1 (another avian influenza virus that can cause severe disease in humans). Influenza (also known as the flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent the flu is by getting a flu vaccination each year.
http://www.concentra.com/patients/health-library/influenza/ http://www.medicinenet.com/influenza/article.htm http://www.livestrong.com/article/30957-influenza-virus-characteristics/ http://www.medicinenet.com/influenza/article.htm http://www.concentra.com/patients/health-library/influenza/ http://www.cdc.gov/flu/spotlights/h7n9-disease-characteristics.htm http://www.concentra.com/patients/health-library/influenza/
what is a characteristic of influenza?