by Tanada » Tue 14 Jan 2014, 11:25:50
$this->bbcode_second_pass_quote('', 'T')he highly contagious equine influenza A virus subtype H3N8 was found to have been the cause of Greyhound race dog fatalities from a respiratory illness at a Florida racetrack in January 2004. The exposure and transfer apparently occurred at horse racing tracks, where dog racing had also occurred. This was the first evidence of an influenza A virus causing disease in dogs. However, serum collected from racing Greyhounds between 1984 and 2004 and tested for canine influenza virus (CIV) in 2007 had positive tests going as far back as 1999. CIV possibly caused some of the respiratory disease outbreaks at tracks between 1999 and 2003.[2]
H3N8 was also responsible for a major dog-flu outbreak in New York state in all breeds of dogs. From January to May 2005, outbreaks occurred at 20 racetracks in 10 states (Arizona, Arkansas, Colorado, Florida, Iowa, Kansas, Massachusetts, Rhode Island, Texas, and West Virginia).[3] As of August 2006, dog flu has been confirmed in 22 U.S. states, including pet dogs in Wyoming, California, Connecticut, Delaware, and Hawaii.[4] Three areas in the United States may now be considered endemic for CIV due to continuous waves of cases: New York, southern Florida, and northern Colorado/southern Wyoming.[5] There is no evidence that the virus can be transferred to people, horses, cats, or other species.[6]
and
$this->bbcode_second_pass_quote('', 'H')3N8 has been identified as the probable cause of the 1889–1890 flu pandemic in humans, and also another epidemic in 1898–1900.[3][4] Before the identification of H3N8 as the likely cause of the 1889 pandemic, the H2N2 subtype was most commonly suggested as the likely cause.[5][6][7] At this point, it is not possible to identify the viral subtype for either the 1889 or 1900 outbreak with certainty.[8]
A 1997 study found H3N8 was responsible for over one quarter of the influenza infections in wild ducks.[9] In 1963, the H3N8 (A/equine/2/Miami/63) subtype created an epidemic of equine influenza in Miami and subsequently spread throughout North and South America and Europe, creating massive outbreaks during 1964 and 1965. Since 1963, the H3N8 virus has drifted along a single lineage at a rate of 0.8 amino acid substitutions per year. Between 1978 and 1981, there were widespread epidemics of the A/equine/2 strain throughout the USA and Europe despite the development of vaccines. Since the late 1980s, evolution of the H3N8 virus has diverged into two families: an "American-like" lineage and a "European-like" lineage.[10]
Equine/Canine Influenza is currently circulating in the pet/working dog population of the USA. The current strain is rarely picked up by human owners of the dogs, however a sub strain of this form of the flu is believed to have caused the 1898-1890 outbreak that killed over a Million people back when the world population was around 2 Billion humans. This flu is second only to H1N1 Spanish Influenza in the number of humans it has killed in a pandemic season, and the more dogs which catch it this season the more likely the human pandemic strain is to reappear.
This year (2013-2014) flu shot does not give protection against this strain, it covers H1N1, and H3N2 but not H3N8. There is some expectation that H3N2 antibodies will slow down H3N8 even though they are not specifically targeted at it because they share the H3 protein as an immune response target. Human Influenza comes in three groups, A, B and C, and type A has at least 144 different forms from H1N1 to H16N9. There are 16 H types and 9 N types giving a total strain set of 144 different flu viruses. WHO and the CDC select the two most Common A HhNn strains each summer and put them in the flu shot along with the most common B strain.