Waterfowl Diseases Update Past 15 Years Nicole Beaver

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Waterfowl DiseasesUpdate Past 15 YearsNicole
Beaver
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• Avian Cholera
• Avian Botulism
• Duck viral enteritis (DVE)
• West Nile Virus
• Avian Vacuolar Myelinopathy (AVM)
• Avian Influenza

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Avian Cholera

• Most important disease in N. American waterfowl
• Kills quickly 6-12 hours
• First diagnosed in 1940
• Outbreaks in new areas have become more frequent
  in the past 20 years

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Avian Cholera Recent Research

• Little is known about the interactions between
  the host, the agent, and the environment
• Outbreaks tend to occur in wetlands/populations
  that have suffered previous outbreaks
• Agent could survive in infected wetland OR in
  carriers birds

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Recent Research cont.

• Sacramento National Wildlife Refuge
• Water and sediments tested for Pasteurella
  multocida
• The bacteria was found in samples taken during or
  soon after outbreaks
• Samples 1-3 months post-outbreak did not contain
  the bacteria
• P. multocida probably doesnt survive long enough
  in the environment to cause the recurring
  outbreaks

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Recent Research cont.

• Carrier birds
• Lesser snow geese from Wrangle Island, Russia and
  Banks Island, Canada
• Blood samples collected each summer and tested
  for antibodies
• 8 of blood samples from the Banks Island pop.
  Contained antibodies (post-outbreak)
• 3 with antibody from Wrangle Island (no
  outbreak)
• More birds infected than once though
• Some survive infection could become carriers
• More research is needed

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Avian Botulism

• Botulism has occurred naturally for centuries,
  however, changes in habitat use may be increasing
  the severity of outbreaks
• Cleaning up carcasses is not completely effective
• More birds die than can be found and removed
• Money going toward cleanups could be better spent
  in more research, or in conserving more wetland
  habitat

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Botulism - Research

• Connection between botulism and blue-green algae
  blooms
• Describe water quality and weather during
  botulism outbreaks
• Increase understanding of carcass-maggot cycles
  and identify other possible carriers

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Duck Virus Entiritis

• 1993 outbreak in Finger Lakes, New York
• Some exposed birds become carriers
• Appear healthy but can transmit the disease to
  others
• A vaccine does exist, but is used primarily in
  breeder ducks

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West Nile Virus

• New York City area 1999
• Spread through U.S., Canada, Mexico, and
  Caribbean
• Flavivirus
• Transmitted by mosquitoes
• Affects about 250 species of bird

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Symptoms of WNV

• Weakness
• Stumbling/trembling
• Head tremors
• Cant fly
• Easily approachable

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West Nile Virus
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WNV Control

• Mainly aimed at prevention
• Mosquito control
• Public reports of dead birds

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Avian Vacuolar Myelinopathy (AVM)

• Recently discovered neurological disease
• Mainly affects bald eagles and American coots
• Also confirmed in mallards, buffleheads,
  ring-necked ducks, and Canada geese
• Occurs from November to March as populations
  migrate in and out of areas
• Arkansas, Georgia, N. and S. Carolina, suspected
  in Texas

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AVM Symptoms

• Lack of muscle control
• Fly into walls, crash-land, appear intoxicated,
  swim upside-down
• Affected birds appear healthy and are alert and
  aware of surroundings
• Lesions in myelin of brain and spinal cord

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Cause

• Unknown
• Not parasitic, fungal, bacterial, viral, or prion
• Associated with submerged aquatic vegetation
• Onset is dose-dependent
• Suspect cause is a toxin natural or man-made

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Research

• Exposure is site specific and seasonal.
• Birds with brain lesions may not exhibit
  symptoms.
• Brain lesions were produced in red-tailed hawks
  in laboratory conditions when fed tissue from
  affected coots.
• An invasive aquatic plant, hydrilla, produced
  brain legions in some laboratory mallards.

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AVM Future Research

• Continue to monitor AVM at lakes where the
  disease occurs and at nearby lakes without
  disease.
• Characterize environmental factors at the sites
  where AVM has occurred. These site
  characterizations will be instrumental for
  developing risk assessment models and may
  generate hypotheses regarding environmental
  conditions conducive for AVM outbreaks.
• Identify the causative agent of AVM.

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Avian Influenza

• Virus which spreads through contact with feces,
  saliva, or nasal discharge
• Mainly found in poultry and wild birds (including
  some waterfowl), but can affect mammals as well
• When the virus jumps species, it mutates

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Symptoms

• Low pathogenic forms are often undetected
• Symptoms may be as slight as ruffled feathers and
  a small decrease in egg production
• Highly pathogenic forms can affect multiple
  internal organs
• 90-100 mortality
• 48 hour incubation

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Avian Influenza

• Low or highly pathogenic
• Depends on strain
• Strain H5N1 is highly pathogenic
• Mortality in more than 80 bird species
• 98 human fatalities
• Low pathogenic forms have occurred in North
  America
• Peak occurrence in N. American ducks is late
  summer and early fall

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H5N1

• Highly contagious among birds
• Does not usually spread to humans
• Close contact with infected birds
• Control
• Ban on birds and bird products from affected
  countries

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Current Situation

• The outbreak is not expected to diminish in
  affected areas
• Ducks are shedding more virus for longer periods
  of time, without showing signs of the illness
• There is little natural immunity to this strain
  among humans