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

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Presentation on theme: "Canine Influenza in New York State David M. Chico, V.M.D. New York State Department of Agriculture and Markets."— Presentation transcript:

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 depend on transmission from one host species to another for survival Influenza viruses are classified as Type A, B or C Influenza viruses are classified as Type A, B or C The subtypes of influenza are named by H and N types The subtypes of influenza are named by H and N types H = hemagglutinin (16 types) allows entrance into cell H = hemagglutinin (16 types) allows entrance into cell N = neuraminadase (9 types) allows exit from 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 Direct transfer from one species to another with unaltered virus i.e transfer of avian influenza H5N1 from chickens to people in Asia i.e transfer of avian influenza H5N1 from chickens to people in Asia Co-infection of a host with different strains of influenza Co-infection of a host with different strains of influenza Allows re-assortment of genes from different viruses to create a novel strain Allows re-assortment of genes from different viruses to create a novel strain This is where pandemic strains come from (’18, ’57, ’68) 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 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 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 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 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 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? The next pandemic? It may also take on more genes that make it less infective 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 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 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 We know how many people became ill with the virus but we don’t know how many were exposed

9 Type A 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 human equine swine avian Neuraminidase human equine swine avian

12 Type A Influenza Surface Antigens Subtype Surface Antigens Hemagglutinin human equine swine avian Neuraminidase human equine swine avian

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

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

16 Canine Influenza Initial investigations during the outbreaks ruled out common pathogens as the source of infection 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 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 Sick dogs were negative for human, swine and avian H3 Positive for equine H3 Positive for equine H3

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

18 New York Outbreak In July/August vet clinics in the NYC and surrounding area reported unusual “kennel cough” cases 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 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 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 Highly suggestive of canine influenza because dogs should not have a positive response to any influenza virus

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

20 Canine Influenza Severe Form High fever (up to 106 ◦ ) High fever (up to 106 ◦ ) Symptoms of pneumonia including increased respiratory rate/effort Symptoms of pneumonia including increased respiratory rate/effort Some dogs with the severe form will die despite supportive care 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 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 80% have the mild form, 20% have the severe form and < 5% will die


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