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Canine Influenza in New York State

Canine Influenza in New York State. David M. Chico, V.M.D. New York State Department of Agriculture and Markets. Background on Influenza Viruses. Influenza viruses depend on transmission from one host species to another for survival Influenza viruses are classified as Type A, B or C

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Canine Influenza in New York State

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  1. Canine Influenza in New York State David M. Chico, V.M.D. New York State Department of Agriculture and Markets

  2. Background on Influenza Viruses • Influenza viruses depend on transmission from one host species to another for survival • Influenza viruses are classified as Type A, B or C • The subtypes of influenza are named by H and N types • H = hemagglutinin (16 types) allows entrance into cell • N = neuraminadase (9 types) allows exit from cell

  3. Hemagglutinin Neuraminidase

  4. Interspecies Transmission • Direct transfer from one species to another with unaltered virus • i.e transfer of avian influenza H5N1 from chickens to people in Asia • Co-infection of a host with different strains of influenza • Allows re-assortment of genes from different viruses to create a novel strain • This is where pandemic strains come from (’18, ’57, ’68)

  5. Influenza Background • Typically, direct transmission of an influenza virus from one species to a new species does not result in sustained transmission

  6. Influenza Background • Multiple virus-host interactions are necessary for replication and horizontal transmission • This presents a barrier to the spread of a virus in a new host • There is some unique characteristic in the 144 victims of avian influenza H5N1 that allows it to be virulent in these people

  7. Influenza Background • If the H5N1 avian influenza virus takes on more genes from other influenza strains it may become more infective and allow human to human spread • The next pandemic? • It may also take on more genes that make it less infective

  8. Influenza Background • The media focuses on the deaths associated with the virus • An important study to do is to test people in the affected areas and see how many people seroconverted but didn’t get sick or die • We know how many people became ill with the virus but we don’t know how many were exposed

  9. TypeA Influenza virus – role of birds The role of waterfowl Have been present for 105 million years All subtypes of flu found Asymptomatic intestinal infection Excrete large amounts of virus in water

  10. Type A Influenza virus – role of birds Domestic birds (chickens, etc): 50 million years respiratory infection/illness can shed lots of virus from respiratory and GI tract can become very ill or die acutely with infection (or be asymptomatic))

  11. Type A Influenza Surface Antigens Subtype Surface Antigens Hemagglutinin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 human equine swine avian Neuraminidase 1 2 3 4 5 6 7 8 9 human equine swine avian

  12. Type A Influenza Surface Antigens Subtype Surface Antigens Hemagglutinin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 human equine swine avian Neuraminidase 1 2 3 4 5 6 7 8 9 human equine swine avian

  13. Infectivity of Influenza • Birds have a receptor for avian influenza viruses • Humans have a receptor for human influenza virus • Swine have both receptor types on their cells Swine are a “mixing” vessel

  14. Canine Influenza There were severe outbreaks of respiratory disease associated with greyhounds on dog tracks in Fl starting in 2003 Outbreaks were later found in dog shelters, humane societies, boarding facilities, and vet clinics

  15. Canine Influenza Initial investigations during the outbreaks ruled out common pathogens as the source of infection Serology on the initial cases were screened for Influenza A/B strains and were positive for Type “A” H3 subtype Sick dogs were negative for human, swine and avian H3 Positive for equine H3

  16. Canine Influenza • The virus was isolated from a dog that died in a Miami shelter in 2004 • Identified as H3N8 • >96% of genomic sequence similar to equine influenza H3N8 • Since all of the canine influenza genes were of equine origin, it was determined the virus “jumped” species from horse to dog

  17. New York Outbreak • In July/August vet clinics in the NYC and surrounding area reported unusual “kennel cough” cases • PH vet Dr. Sally Slavinski of NYCDOHMH was notified of the cases and contacted Dr. E. Dubovi at Cornell • Dr. Dubovi tested samples from sick dogs and they were (+) for H3 influenza • Highly suggestive of canine influenza because dogs should not have a positive response to any influenza virus

  18. Symptoms – 2 Clinical Forms • Mild Form • Moist or dry cough • Low grade fever • Purulent nasal discharge • Unresponsive to AB’s and Cough Suppressants

  19. Canine Influenza Severe Form • High fever (up to 106◦) • Symptoms of pneumonia including increased respiratory rate/effort • Some dogs with the severe form will die despite supportive care • Dogs that die will typically have a very severe pneumonia with lungs that are consolidated and filled with hemorrhagic fluid at necropsy • 80% have the mild form, 20% have the severe form and < 5% will die

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