Excerpt from article:20 cases of the swine flu have been confirmed in the U.S. as of this writing and the CDC expects the disease to spread.
Called swine flu because it originates in pigs and other swine, swine flu is usually spread only from animal to animal. When the disease spreads from swine to humans, the World Health Organization (WHO) and the Centers for Disease Control (CDC) in America keep close tabs on the disease. Concerns grow exponentially when the swine flu is transmissible between humans which has happened with the current swine flu, a strain of Influenza A/H121.
The swine flu virus that has killed at least 80 people in Mexico and infected another 1300 is from the H1N1 strain of influenza A virus. H refers to a protein, Hemagglutinin and N refers to the Neuraminidase protein.
The 20 confirmed cases of the swine flu in the United States are in Texas, California, Ohio, Kansas and New York. Canada has reported 4 confirmed cases of A/H1N1 influenza. The CDC expects the flu to spread. Most of the U.S. cases have been mild so far with only one reported hospitalization.
Variants of the H1N1 influenza are thought to cause nearly half of all flu infections in the world. These seasonal influenza infections are usually mild to moderate. However, one variation of the H1N1 influenza was responsible for the 1918 world wide pandemic that killed between 50 and 100 million people, and infected roughly one third of the world's population at the time. The 1918 flu was called the Spanish flu because it was thought at the time to originate in Spain. Though biologists and other epidemiologists have been studying the 1918 H1N1 strain for over 75 years, many questions about its virulence have never been answered.
All A/H1N1 influenza strains in existence today are descendants of the 1918 pandemic 'Spanish flu.' The Spanish flu was unusual because it struck down normally healthy young adults. It is usually very young children and the elderly who are at highest risk of serious illness from influenza. The 1918 pandemic was first documented in the U.S. in Kansas in March of 1918. Soldiers living in close quarters (WWI was winding down then) proved to be instrumental in the rapid spread of the disease Most of those who became ill in the Spring of 1918 had mild symptoms and recovered. But when a second wave of the flu spread in the fall, the disease was much more aggressive and dangerous. The flu acted rapidly and caused a severe type of pneumonia that resulted in numerous fatalities within a matter of days and sometimes hours after contracting the disease.
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