Canine Influenza in New York Canine Influenza in New York StateState

David M. Chico, V.M.D.David M. Chico, V.M.D.

New York State Department of Agriculture New York State Department of Agriculture and Marketsand Markets

Background on Influenza Background on Influenza VirusesViruses

Influenza viruses depend on Influenza viruses depend on transmission from one host transmission from one host species to another for survivalspecies to another for survival Influenza viruses are classified as Type Influenza viruses are classified as Type

A, B or CA, B or C The subtypes of influenza are named by The subtypes of influenza are named by

H and N typesH and N types H = hemagglutinin (16 types) allows H = hemagglutinin (16 types) allows

entrance into cellentrance into cell N = neuraminadase (9 types) allows exit N = neuraminadase (9 types) allows exit

from cell from cell

Hemagglutinin

Neuraminidase

Interspecies TransmissionInterspecies Transmission

Direct transfer from one species to Direct transfer from one species to another with unaltered virusanother with unaltered virus i.e transfer of avian influenza H5N1 from i.e transfer of avian influenza H5N1 from

chickens to people in Asiachickens to people in Asia

Co-infection of a host with different Co-infection of a host with different strains of influenzastrains of influenza Allows re-assortment of genes from Allows re-assortment of genes from

different viruses to create a novel straindifferent viruses to create a novel strain This is where pandemic strains come This is where pandemic strains come

from (’18, ’57, ’68)from (’18, ’57, ’68)

Influenza BackgroundInfluenza Background

Typically, direct transmission of an Typically, direct transmission of an influenza virus from one species to a influenza virus from one species to a new species does not result in new species does not result in sustained transmission sustained transmission

Influenza BackgroundInfluenza Background

Multiple virus-host interactions are Multiple virus-host interactions are necessary for replication and necessary for replication and horizontal transmissionhorizontal transmission This presents a barrier to the spread of a This presents a barrier to the spread of a

virus in a new hostvirus in a new host There is some unique characteristic in There is some unique characteristic in

the 144 victims of avian influenza H5N1 the 144 victims of avian influenza H5N1 that allows it to be virulent in these that allows it to be virulent in these peoplepeople

Influenza BackgroundInfluenza Background

If the H5N1 avian influenza virus If the H5N1 avian influenza virus takes on more genes from other takes on more genes from other influenza strains it may become influenza strains it may become more infective and allow human to more infective and allow human to human spreadhuman spread The next pandemic?The next pandemic?

It may also take on more genes that It may also take on more genes that make it less infectivemake it less infective

Influenza BackgroundInfluenza Background The media focuses on the deaths The media focuses on the deaths

associated with the virusassociated with the virus

An important study to do is to test An important study to do is to test people in the affected areas and see people in the affected areas and see how many people seroconverted but how many people seroconverted but didn’t get sick or diedidn’t get sick or die We know how many people became ill We know how many people became ill

with the virus but we don’t know how with the virus but we don’t know how many were exposedmany were exposed

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

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))

Type A Influenza Surface Antigens

Subtype Surface AntigensHemagglutinin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

human equine swineavian

Neuraminidase 1 2 3 4 5 6 7 8 9

humanequineswineavian

Type A Influenza Surface Antigens

Subtype Surface AntigensHemagglutinin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

human equine swineavian

Neuraminidase 1 2 3 4 5 6 7 8 9

humanequineswineavian

Infectivity of InfluenzaInfectivity of Influenza

•Birds have a receptor for avian influenza virusesBirds have a receptor for avian influenza viruses

•Humans have a receptor for human influenza Humans have a receptor for human influenza virusvirus

•Swine have both receptor types on their cellsSwine have both receptor types on their cells

Swine are a “mixing” vessel

Canine InfluenzaCanine Influenza• There were severe outbreaks of There were severe outbreaks of respiratory disease associated with respiratory disease associated with greyhounds on dog tracks in Fl greyhounds on dog tracks in Fl starting in 2003starting in 2003

• Outbreaks were later found in dog Outbreaks were later found in dog shelters, humane societies, boarding shelters, humane societies, boarding facilities, and vet clinicsfacilities, and vet clinics

Canine InfluenzaCanine Influenza• Initial investigations during the outbreaks Initial investigations during the outbreaks ruled out common pathogens as the ruled out common pathogens as the source of infectionsource of infection

•Serology on the initial cases were Serology on the initial cases were screened for Influenza A/B strains and screened for Influenza A/B strains and were positive for Type “A” H3 subtypewere positive for Type “A” H3 subtype

•Sick dogs were negative for human, Sick dogs were negative for human, swine and avian H3swine and avian H3•Positive for equine H3Positive for equine H3

Canine InfluenzaCanine Influenza

The virus was isolated from a dog that The virus was isolated from a dog that died in a Miami shelter in 2004died in a Miami shelter in 2004

Identified as H3N8Identified as H3N8 >96% of genomic sequence similar to >96% of genomic sequence similar to

equine influenza H3N8equine influenza H3N8 Since all of the canine influenza genes Since all of the canine influenza genes

were of equine origin, it was determined were of equine origin, it was determined the virus “jumped” species from horse to the virus “jumped” species from horse to dogdog

New York OutbreakNew York Outbreak

In July/August vet clinics in the NYC and In July/August vet clinics in the NYC and surrounding area reported unusual surrounding area reported unusual “kennel cough” cases“kennel cough” cases

PH vet Dr. Sally Slavinski of NYCDOHMH PH vet Dr. Sally Slavinski of NYCDOHMH was notified of the cases and contacted was notified of the cases and contacted Dr. E. Dubovi at CornellDr. E. Dubovi at Cornell

Dr. Dubovi tested samples from sick dogs Dr. Dubovi tested samples from sick dogs and they were (+) for H3 influenzaand they were (+) for H3 influenza Highly suggestive of canine influenza because Highly suggestive of canine influenza because

dogs should not have a positive response to dogs should not have a positive response to any influenza virusany influenza virus

Symptoms – 2 Clinical Symptoms – 2 Clinical FormsForms

Mild FormMild Form Moist or dry coughMoist or dry cough Low grade feverLow grade fever Purulent nasal dischargePurulent nasal discharge Unresponsive to AB’s and Cough Unresponsive to AB’s and Cough

SuppressantsSuppressants

Canine InfluenzaCanine InfluenzaSevere FormSevere Form

High fever (up to 106High fever (up to 106◦◦)) Symptoms of pneumonia including Symptoms of pneumonia including

increased respiratory rate/effortincreased respiratory rate/effort Some dogs with the severe form will die Some dogs with the severe form will die

despite supportive caredespite supportive care Dogs that die will typically have a very Dogs that die will typically have a very

severe pneumonia with lungs that are severe pneumonia with lungs that are consolidated and filled with hemorrhagic consolidated and filled with hemorrhagic fluid at necropsyfluid at necropsy

80% have the mild form, 20% have 80% have the mild form, 20% have the severe form and < 5% will diethe severe form and < 5% will die