Influenza A/H1N1 aka Swine Flu

The CDC is collaborating with the WHO to investigate reported outbreaks of the swine flu in Mexico, California and Texas. The WHO reports that in the USA, there have been 7 confirmed cases, 5 suspected cases, and no mortalities, mostly affecting young adults (influenza usually afflicts the young, old and immunocompromised). In Mexico, Influenza-like-illness (ILI) has been under surveillance since March 18, where there have been approximately 1000 reported cases, with 59 deaths in Mexico City and 3 deaths in San Luis Potosi located in central Mexico (although Mexicans have commented that the situation is far worse than depicted by authorities).  The strains are sensitive to oseltamivir but resistant to amantadine and rimantadine.  Symptoms of the respiratory tract infection include fever, sore throat, cough, myalgia and malaise. If the cases we have seen result in Antigenic Shift (complete change in HA and NA), there is risk for h1n1 pandemic, since we have no antibodies against the virus. In 1918, a swine flu virus transferred its HA to a human strain (HSW), leading to the Spanish Flu/H1N1 pandemic which resulted in 20 million deaths across the globe. Remember: don’t give children aspirin if they present with these symptoms (Reye’s Syndrome) and follow the CDC, WHO and USA government pandemic flu site for updates.  Here’s a quick refresher on the bolts and nuts of the flu. Influenza viruses are orthomyxoviridae. At the core of these spherical virions lie 8 segments of negative stranded RNA assembled with nucleocapsid protein into a helical symmetry capsid. An outer membrane surrounds the nucleocapsid, and is studded with glycoprotein spikes with hemagglutinin activity (HA) and neuraminidase activity (NA). M proteins anchor these spikes, which are responsible for influenza’s virulence. There are three types of influenza virus: A, B and C. A infects humans, mammals and birds, whereas B and C only infect humans. Follow this for an interesting read put out by the WHO on oseltamivir resistance in H1N1. 

  1. Hana Akselrod Reply
  2. | Acne Treatments Asia Reply

    If you look at the pandemic of 1977, when H1N1 or Swine Flu re-emerged after a 20 year absence, there is no shift in age-related mortality pattern. The 1977 “pandemic� is, of course, not considered a true pandemic by experts today, for reasons that are not entierely consistent. It certainly was an antigenic shift and not an antigenic drift. As far as I have been able to follow the current events, the most significant factor seems to have been that most people, who were severely affected, were people with other medical conditions.

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