Introduction/Background/History:Influenza better known as "The Flu" strikes the world every year infecting millions of people in different countries. Influenza is a deadly virus and is an extremely contagious respiratory disease caused by influenza viruses. The flu appears more frequently in winter and early spring. The influenza virus attacks the body by spreading through the upper or lower respiratory tract. Traces of influence are documented as early as the 12th century. The flu reappeared on Earth at the beginning of the 20th century, during the First World War in China. Infecting approximately 20%-40% of the world's population it became ill. This pandemic virus has killed more than any other disease in human history, with a death toll ranging from 50 to 100 million people. Nearly 675,000 people died in the United States from this epidemic. The world population in 1918 was 1.8 billion, in 2014 it amounted to 7.1 billion. It is estimated that around 8 million people have fallen ill with the flu in Spain. Known as the “Spanish Flu,” it was widely reported in newspapers across Spain. The Spanish Flu caused so many people to die from this disease that it was called the “Black Death” in the Middle Ages. The virus spread rapidly as troops aboard warships traveled to different parts of Earth during World War I. In February 1957, a new influenza virus emerged in Asia, officials predicting another pandemic. Health officials monitored flu epidemics until a vaccine could be produced. Unfortunately the immune systems of the elderly were too weak to fight the flu, approximately 69,800 people died, of which the majority were elderly. Just over ten years after the second epidemic in 1968, health officials detected in the United States a...... middle of paper ......pe A viruses are the most common of the three in cases that concern human beings. Although influenza is more stabilized than it has ever been in history, there are still epidemics around the world. Works Cited Watters, MD, WH. (1919). Flu vaccines. The Boston Medical and Surgical Journal, 181 (10), PP 727-313.Slemons, Richard. D. (1973). Influenza A viruses isolated from free-flying wild ducks in California. Avian Diseases, 18(1), PP 321-342.Potter, C.W. (2008). A story of influence. Journal of Applied Microbiology, 91 (4), PP 572-579. Petersen, EA (2014). Influenza Tucson, Ariz, Medfilms Inc. Coila, Bridget.. (2011, March 11). About type B strain influenza. Retrieved February 7, 2014, from http://www.livestrong.com/article/164798-about-type-b-strain-flu/