Teach Cough Hygiene Everywhere/Swine flu

Where do swine flus originate?

(Be sure to watch the Dr. Brilliant video on this whole issue!)

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http://www.sciencedaily.com/releases/2012/02/120223103918.htm Swine influenza (swine flu) is a respiratory disease of pigs caused by type A influenza viruses that regularly cause outbreaks of influenza in pigs. Influenza viruses that commonly circulate in swine are called “swine influenza viruses” or “swine flu viruses.” Like human influenza viruses, there are different subtypes and strains of swine influenza viruses. The main swine influenza viruses circulating in U.S. pigs in recent years are:

   swine triple reassortant (tr) H1N1 influenza virus
   trH3N2 virus
   trH1N2 virus

Swine flu viruses do not normally infect humans. However, sporadic human infections with swine influenza viruses have occurred. When this happens, these viruses are called “variant viruses.” http://www.cdc.gov/flu/swineflu/

Why are human infections with variant viruses of concern?

Influenza viruses that infect pigs are different from human influenza viruses. Thus, influenza vaccines made against human influenza viruses are generally not expected to protect people from influenza viruses that normally circulate in pigs. In addition, because pigs are susceptible to avian, human and swine influenza viruses, they potentially may be infected with influenza viruses from different species (e.g., ducks and humans) at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus that could spread easily from person-to-person. (That is called "antigenic shift and is how pandemics occur.") SOURCE http://www.cdc.gov/flu/swineflu/keyfacts-variant.htm This is what happened in 2009 when an influenza A H1N1 virus with swine, avian and human genes emerged in the spring of 2009 and caused the first pandemic in more than 40 years. SOURCE: Ibid