Waterfowl Diseases Update – Past 15 Years Nicole Beaver

1. Waterfowl DiseasesUpdate – Past 15 YearsNicole Beaver

2. Avian Cholera • Avian Botulism • Duck viral enteritis (DVE) • West Nile Virus • Avian Vacuolar Myelinopathy (AVM) • Avian Influenza

3. 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

4. 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

5. 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 doesn’t survive long enough in the environment to cause the recurring outbreaks

6. 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

7. 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

8. 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

9. 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

10. 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

11. Symptoms of WNV • Weakness • Stumbling/trembling • Head tremors • Can’t fly • Easily approachable

12. West Nile Virus

13. WNV Control • Mainly aimed at prevention • Mosquito control • Public reports of dead birds

14. 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

15. 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

16. 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

17. 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.

18. 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.

19. 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

20. 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

21. 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

22. 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

23. 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