West Nile Virus; Avian Implications

1. West Nile Virus; Avian Implications By Jason Chudy and Beth Laskowski September 27,2002

2. West Nile Virus Background • Flavivirus commonly found in Africa, West Asia, and the Middle East • Other flavivirus diseases include Yellow Fever and St. Louis Encephalitis • Infects humans, birds, mosquitoes, horses and some other mammals • Prior to 1999 it had not been previously documented in the Western Hemisphere

3. West Nile Virus Background (cont.) • Causes two primary disease forms • West Nile Fever • West Nile encephalitis, West Nile meningitis, or West Nile meningoencephalitis • WNV can be transmitted year round • Thought to over-winter in the adult Culex species of mosquito • Permanently established in the Western Hemisphere

4. West Nile Fever Mild disease Flu like symptoms Lasts only a few days No apparent long-term health effects West Nile Encephalitis / meningitis / meningoencephalitis More severe disease Causes inflammation of the brain, tissues surrounding the brain an spinal cord, or both fatal West Nile Virus Disease Forms

6. Back to the ‘skeeters’ • Population control of mosquitoes could decrease frequency of infection and rate of spread. • Culex has minimal requirements for reproduction and thrives in urban areas. • Culex can complete reproduction in a week. • Other species carry the disease: • Aedes albopictus, A cinereus, A. vexans, Anopheles barberi, A. punctipennis, A. quadrimaculatus, A. coquillettidia A.perturbans, Culex pipiens, C. restuans, C. nigripalpus, C. quinquefasciatus, C. salinaris, Culiseta melanura, Ochlerotatus atlanticus, O. atropalpus, O. Canadensis, O. cantator, O. japonicus, O. sollicitans, O. taeniorynchus, O. tormentor, O. trivittatus, Orthropodomyia signiferus Psorophora columbiae, P. ferox, Uranotaenia sapphirina

7. ‘Skeeters’ continued • Why do we see cases in the winter? • Confused mosquito? • Dormancy in bird (ie chickens don’t get sick) • Mammalian vector (isolated WNV in mouths of mice) • We are now seeing a species of mosquito that is a day feeder • Have to watch our pets during the day now as well!

10. WNV in Bird Populations • Birds are far more likely than people and other mammals to become infected and sickened by the WNV • By Sept 5 2002, WNV had been detected and confirmed WNV in at least 3,243 dead crows and in 2,232 other dead birds • Migratory birds are likely a key means by which the virus is transported to new areas

11. WNV in Bird Populations cont. • In some species, most notably the Corvids, the virus causes disease that is often fatal in infected birds. • It has been shown to be near 100% fatal in crows. • Bird species may seroconvert and carry the virus without becoming sick • WNV has also been confirmed as the cause of death of a privately owned Macaw

12. WNV Bird Cases in Michigan

13. Native North American Species Found Positive for WNV • At least 111 different native North American bird species have tested positive in surveillance efforts • Some species affected: • Crow • Mallard, wood ducks • Bald, golden eagles • Canada goose • Barred, great horned, short eared, and snowy owls • Pigeon • American robin • Broad-winged, cooper’s, red-shouldered, red-tailed, and sharp-shined hawks • Wild turkey • Flamingo

14. WNV in Raptors and Owls • According to the USGS National Wildlife Health Center, there have been daily reports of raptor and owl morbidity and mortality due to WNV since August 10 (complete diagnostic work up and confirmed diagnoses are still pending) • Most of the raptor and owl cases seem to be centered around the Midwest with the following states reporting deaths: • Ohio, Iowa, Indiana, Michigan, Illinois, Wisconsin, Minnesota, Pennsylvania, Kentucky, Maryland and Virginia

15. WNV in Raptors and Owls cont. • Probable cause of death of two flamingos and two snowy owls at the Detroit Zoo as well as the two snowy owls at Lansing’s Potter Park Zoo

16. Symptoms of WNV in Raptors • WNV presents as three phases • Phase 1 – depression, anorexia, weight loss, sleeping, pinching off blood feathers, and elevated WBC count • Phase 2 – the above plus head tremors, green urates (liver necrosis), mental dullness, central blindness, lack of awareness of surroundings, ataxia, weakness in legs • Phase 3 – more severe tremors, seizures

17. West Nile Virus

18. Differential Diagnosis • Eastern equine encephalomyelitis • Avian influenza • Newcastle disease • West Nile Virus

19. Pathogenesis • WNV specificity for macrophages and nervous tissue responsible for progression of disease. • Nerve cell bodies and dendrites of Purkinje cells of the cerebellum most common site. • Dysfunction of neurons and macrophages results in typical calvarial hemorrhage and neurological symptoms.

20. Necropsy lesions • Calvarial hemorrhage • Severe necrotic myocarditis • Splenomegaly • Meningeal hemorrhage and cerebral edema • Intestinal hemorrhage • Meningitis composed primarily of lymphocytes, and plasma cells. Heterophils were also seen on occasion. Perivascular cuffing • Splenic abnormalities seen as a decrease in lymphocytes, fibrin deposition, and coagulative necrosis, thrombosis, infearction • Hepatitis was seen in many of the birds • Pretty much every tissue has some kind of lesion with WNV (renal, lungs, ovaries

21. Gross pathology of WNV infection in birds

22. Ultrasound findings

23. Histological findings • Meningitis :primarily lymphocytes and plasma cells. Heterophils were also seen on occasion. • Perivascular cuffing • Spleen: decrease in lymphocytes, fibrin deposition, coagulative necrosis, thrombosis, infarction • Hepatitis • Pretty much every tissue has some kind of lesion with WNV (renal, lungs, ovaries)

24. Histopathology and IHC of WNV Infection in Birds

25. Treatment Options?? • There is no prescribed treatment • Supportive care can be provided and recovery does seem to be possible in these species • Best prognosis if intervention is done prior to phase 2 • Intervention at phase 3 will probably not alter disease course

26. Prevention of WNV in Birds • Protect the animals from mosquito bites • Mosquito netting, indoor housing • Horse vaccine ? • 2 doses, 3-4 weeks apart w/out side effects • Efficacy ? • Experimental results showed some protection with WNV challenge • 5/11 vaccinated American crows survived challenge • 0/9 unvaccinated crows survived

27. Surveillance • Hotline to call if dead birds found. • Web-based reporting • Necropsy headed up by our own Jon Patterson. • Only birds in counties that have never had a positive test for WNV will be tested. • Mosquito surveillance

28. Can it get any worse? • 1st canine case demonstrated in Illinois. • 3 squirrels, a wolf and llama also died from the virus. • 4 organ transplant recipients contracted the disease • Warning on front of Lansing State Journal about blood transfusions.

29. Al Quida Mosquito? • The New York 99 strain is very similar to the strain isolated in a goose from Israel 1998. • Bioport was investigated by Congress because they we deemed ‘untrustworthy’. • Bioports operating plans were discovered by American forces at a Afghanistan encampment. • Saudi Arabian owned Bioport found to have direct links to Osama bin Laden

30. Hussein’s new army? • Hussein official/Iraqi defector warned the US of the threat of an altered West Nile virus 2 months before the first case in the summer of 1999.

31. In the News: • “I think we have to ask ourselves: Is it a coincidence that we are seeing such an increase in West Nile virus, or is that something that is being tested as a biological weapon against us?” -Senator Patrick Leahy, chairman of the Senate Judiciary Committee on a recent radio broadcast in Vermont.

32. -the Onion Bush Sends Troops To West Nile

33. Questions? • "There's an old saying in Tennessee…I know it's in Texas, probably in Tennessee...that says: Fool me once, shame on……shame on you. Fool me...you can't get fooled again." – President Bush Nashville, TN, Sept. 17, 2002.