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West Nile Virus April 2003

West Nile Virus April 2003. Emi Kate Saito, VMD, MSPH National Wildlife Health Center Madison, WI. 1. Emi Kate Saito. 1993: BS – Zoology and Biological Aspects of Conservation, Univ. of Wisconsin-Madison 1997: VMD – Veterinary Medicine, Univ. of Penn.

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West Nile Virus April 2003

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  1. West Nile VirusApril 2003 Emi Kate Saito, VMD, MSPH National Wildlife Health Center Madison, WI 1

  2. Emi Kate Saito • 1993: BS – Zoology and Biological Aspects of Conservation, Univ. of Wisconsin-Madison • 1997: VMD – Veterinary Medicine, Univ. of Penn. • 1997-1998- Dept. of Biology, Emory University Graduate School (Population Biology, Ecology and Evolution) • 1998-2000 – Small animal Practice, Atlanta & Annapolis • 2000-2001- MSPH- Epidemiology, Emory University • 2001 WNV Season: DeKalb Co. Board of Health, Atlanta GA • 2002: USGS NWHC • 608-270-2456 • esaito@usgs.gov • www.nwhc.usgs.gov (New Hire picture – not my most flattering picture) 2

  3. Classification • Family:Flaviviridae • Genus:Flavivirus Japanese Encephalitis Antigenic Complex • Complex includes: • Alfuy • Cacipacore • Japanese Encephalitis • Koutango • Murray Valley Encephalitis • St. Louis Encephalitis • Rocio • Stratford • Usutu • West Nile • Yaounde (www.niaid.nih.gov/newsroom/focuson/bugborne01/wnile.htm) 3

  4. Transmission Cycle http://www.cdc.gov/ncidod/dvbid/westnile/misc/slides/nasci/slide13.htm 4

  5. Vector Control/Disease Prevention 5

  6. U.S. and WNV • NY99 strain closely related to Isr98 • High avian mortality associated with human cases • Increased sensitivity of crows 6

  7. WNV Surveillance, United States: Dead Bird Data, 2002(as of January 2003) • 124,854 dead birds reported • 31,514 tested (25%) • 15,745 WNV-positive (50%) • 8,420 crows (53%) • 7,325 birds of other spp. (47%) 7

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  12. NWHC Submissions tested for WNV, 2002 12

  13. 1999 2000 2001 2002 # Tested % Positive # Tested % Positive # Tested % Positive # Tested % Positive American Crow 235 12.8 558 13.3 1011 34.6 686 32.9 Other Corvidae 19 10.5 93 10.8 761 9.6 1030 29.2 Birds of Prey 34 5.9 159 4.4 222 4.1 155 20.6 Other Birds 216 0.5 1117 0.1 597 1.0 584 7.2 Mammals 259 0 76 0 3 0 13 7.7 Herps 0 0 3 0 0 0 0 0 Total 763 4.6 2006 4.6 2594 16.9 2468 24.4 Frequency of Positive Submissions, NWHC 1999-2002 13

  14. Species found with WNV infection • 167 (dead) bird species • 18 mammal species • wolf • squirrels (grey, fox) • reindeer • sheep • harbor seal • Farm-raised alligators • Serology 14

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  16. Research projects 16

  17. Potential vectors of West Nile virus (based on laboratory vector competence studies) Efficient Moderate Inefficient Ae. albopictus Ae. aegypti Ps. ferox Ae. vexans Cx. salinarius Cq. perturbans Cx. tarsalisCx. nigripalpus Cx. pipiens Oc. canadensis Oc. atropalpus Cx. quinquefasciatus Oc. cantator Oc. j. japonicusCx. restuans Oc. sollicitans Oc. taeniorhynchus Oc. triseriatus 17 (Turrell et al., 2001, 2002)

  18. 18 Bird Reservoir Competency Study (laboratory-based) Very Moderate Weak Not • Blue Jay (4) • Common • Grackle (6) • House Finch (2) • Am. Crow (8) • House Sparrow (6) • Ring-billed gull (2) • Black-billed • Magpie (3) • Am. Robin (2) • Red-winged • Blackbird (3) • Killdeer (2) • GHO (1) • Am. Kestrel (2) • Fish Crow (8) • Mallard (2) • European • Starling (6) • Mourning Dove (3) • Northern • Flicker (1) • Canada Goose (3) • Am. Coot (1) • Rock Dove (6) • Chicken (11) • Northern Bobwhite (3) • Ring-necked Pheasant (3) • Budgerigar (3) • Monk • Parakeet (3) • Japanese Quail (3) Komar et al., 2003, EID 9(3): 311-322; www.cdc.gov/ncidod/eid/vol9no3/02-0628.htm

  19. 19 Experimental WNV Mortality Species n mortality rate American Crow 20 100 Black-billed Magpie 5 100Blue Jay 6 83House Finch 3 67Fish Crow 11 64Ring-billed Gull 2 50Common Grackle 10 40House Sparrow 12 25 NO mortality in Eur. Starlings (6), Rock Doves (6), Chicken (18), Ring-necked Pheasant (3), Canada Goose (3), Am. Robin (3), Red-winged Blackbird (3), Mourning Dove (3), Budgerigar (3), Monk Parakeet (3), Japanese Quail (3), Northern Bobwhite (3) Komar et al., 2003, EID 9(3): 311-322; www.cdc.gov/ncidod/eid/vol9no3/02-0628.htm

  20. Alternative modes of Transmission • Cage mate transmission • Am. Crow (4) • Black-billed Magpie (2) • Blue Jay (2) • Ring-billed Gull (1) • Chicken (1) • Oral transmission • Am. Crow (3, susp.; 6, bird) • House Finch (1, mosq.) • House Sparrow (6, susp.) • Common Grackle (4, susp.) • GHO (1, mouse) • Cloacal Shedding (crows) 20 Komar et al., 2003, EID 9(3): 311-322; www.cdc.gov/ncidod/eid/vol9no3/02-0628.htm

  21. NWHC Projects • Crow Study • 2000 • OK • Mallard Study • Crane Vaccination Study • Raptors • Red-cockaded Woodpecker • Amikihi • Waterfowl 21

  22. Migratory Bird Sampling http://migratorybirds.pacific.fws.gov/flyways_map.htm 22

  23. Symptoms of WNV Infection? • General weakness, lethargy • Emaciation • Sedentary • Difficulty maintaining balance, trembling • Inability to walk, perch, stand, or fly • Do not respond normally to danger 23

  24. NWHC Raptor Cases, 2002 • NWHC received 56 raptors • Diagnostic Testing done • Findings • Significance? 24

  25. 25 Other reports: • Raptor Center at U. of Minnesota • SCWDS • Other diagnostic laboratories • New York & New Jersey • Raptor rehabilitators I’ve gone blind?! Help!!

  26. Other avian morbidity/mortality: • Lack of birds/rapid disappearance • Finches • Pelicans, cranes • Blue Jays…. • Recrudescence of raptor cases? 26

  27. Questions still to be answered… • Why the high avian mortality associated with NY99 Strain? • What impact has WNV had on the bird populations? • What other species are being significantly affected? • What impact will WNV have on endangered/threatened bird species? • Do migratory birds really play an important role in the spread of the virus? • Are there other modes of transmission among bird populations? • What birds are the important reservoirs for maintaining natural transmission? • How is the virus over-wintering? • Many, many more…. ??!??!? 27

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