The Influenza A H1N1 world pandemic



In the 2009 flu pandemic, the virus isolated from patients in the United States was found to be made up of genetic elements from four different flu viruses – North American Mexican influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe – "an unusually mongrelised mix of genetic sequences." This new strain appears to be a result of reassortment of human influenza and swine influenza viruses, in all four different strains of subtype H1N1.

Preliminary genetic characterization found that the hemagglutinin (HA) gene was similar to that of swine flu viruses present in U.S. pigs since 1999, but the neuraminidase (NA) and matrix protein (M) genes resembled versions present in European swine flu isolates. The six genes from American swine flu are themselves mixtures of swine flu, bird flu, and human flu viruses.[15] While viruses with this genetic makeup had not previously been found to be circulating in humans or pigs, there is no formal national surveillance system to determine what viruses are circulating in pigs in the U.S.

Influenza A virus subtype H1N1, also known as A(H1N1), is a subtype of influenzavirus A and the most common cause of influenza (flu) in humans. Some strains of H1N1 are endemic in humans, including the strain(s) responsible for the 1918 flu pandemic which killed 20-100 million people worldwide. Less virulent H1N1 strains still exist in the wild today, worldwide, causing a small fraction of all influenza-like illness and a large fraction of all seasonal influenza. H1N1 strains caused roughly half of all flu infections in 2006. Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).

In March to June of 2009, tens of thousands of laboratory-confirmed infections and a number of deaths were caused by an outbreak of a new strain of H1N1.

Comments

Popular posts from this blog

Sang Penambal Jantung Bocor

Apple iPod nano 8 GB Pink

BlackBerry Curve 8330