West Nile Virus

1. West Nile Virus Greg Chrislip Public Health Entomologist WV Department of Health and Human Resources

2. Other bloodsucking insects merely annoy, but mosquitoes insult. By night, these slow decadent flies whine around our heads, always vanishing when the light goes on. By day, they don’t even pay us the respect of evasive action, content to be smeared across our exteriors in stains of protoplasm rather than curtail their orgies…

3. Stay your hand, bear the sting, and watch as she deliberately probes with her six stilettos, injects anticoagulant, swills your blood until her abdomen resembles a ripe aneurysm, voids on your skin, and finally raises a hind leg in doglike salute. Audubon: Incite, October 2001

4. Dead Birds Seroprevalence (birds) Captive sentinel animals Mosquito pools Veterinary Human 16,739 270 1640 6,604 14,571 4,156 (284 deaths) How Much Activity in 2002?Reported to CDC and Verified as of 15 April 2003 44 States and DC

5. CDC Website

6. New Modes Of Transmission in 2002 • Transplant Recipients • Blood Transfusion • Transplacental • Breast Milk • Occupational Exposure

7. West Virginia West Nile Surveillance 2002 • From May 1 – November 30, 2002 the LHDs have reported 6,952 dead birds to the Infectious Disease Epidemiology Program. • 253 Crows and 6,699 other species

8. West Virginia West Nile Surveillance 2002 • From May 1 to November 30, 2002 a total of 903 dead birds have been submitted to the Southeastern Cooperative Wildlife Disease Study (SCWDS) at the University of Georgia or the National Wildlife Health Center in Madison, WI for virus testing.

9. West Virginia West Nile Dead Bird Surveillance 2002 • 77 - Positive for West Nile virus • 763 - Negative for West Nile virus • 30 - Not Tested (received by lab; too deteriorated to test) • 18 – status unknown, do not know if sent, lost in mail, lost at lab, etc. • Total 903

10. West Virginia West Nile Surveillance 2002 • Three positive horses have been identified in the state (Mercer, Cabell and Jefferson counties). • Three positive human cases (1 Putnam and 2 Wood counties)

12. Dead Bird Surveillance Dead Bird Surveillance 2003

13. 2003 Dead Bird Testing • Test 1,000 dead birds at the Southeastern Cooperative Wildlife Disease Study (SCWDS) • ALL SPECIESof dead birds with no obvious signs of trauma will be acceptable. • Fresh specimens, less than 24 hours old, without signs of decay should be sent in.

14. Mosquito Surveillance

15. Objectives • Identification of the mosquito species that are present in an area. • Determining whether they are important WNV vector species. • Identification and mapping of mosquito breeding habitats for larval control purposes. • Defining the geographic area affected by mosquitoes originating from identified habitats.

16. Objectives (cont.) • Determining the population density. • Determining when mosquito populations are at the appropriate developmental or behavioral stage to apply control measures. • Determining the effectiveness of local mosquito control measures.

17. Objectives (cont.) • Determining whether vector mosquito species are present in an area; whether they are infected with arboviruses. • Determining the mosquito infection rate for arboviruses in vector species populations. • Determining the seasonal activity patterns of local mosquito species.

18. Mosquito Biology • 4 distinct stages in their lifecycle • Egg, larva, pupa and adult • “Most” females blood feed • Over 3,000 species world-wide

19. Female Mosquito (Cx. quinquefasciatus) Blood Feeding on a finger

20. Culex Mosquito laying eggs Egg raft

21. Siphon Culex–type Mosquito Larvae “ wigglers”

22. Mosquito Pupae “tumblers” trumpets

23. 2002 Mosquito Surveillance • A total of 25 species are shown to be positive for West Nile virus in 2002. • 11 additional species of mosquitoes were positive for the virus in previous years (1999- 2001) • Total number of mosquito species testing positive for West Nile Virus: 36

24. 2002 Mosquito Surveillance • Genera that tested positive included: • Aedes (4 species), Anopheles (6 species), Coquillettidia (1 species),Culex (8 species), Culiseta (2 species), Deinocerites (1 species)Ochlerotatus (9 species), Orthopodomyia (1 species), Psorophora (3 species), and Uranotaenia (1 species).

25. Surveillance • Identifies locations where mosquito populations may be increasing. • Allows identification of potential vector species. • Adult surveillance can assist in pinpointing larval sites. • Adult surveillance • CDC Gravid Traps • CDC Miniature Light Traps • Larval Surveillance • Dippers and turkey basters

26. Larval Surveillance • Assist with locating breeding sites after the finding of a positive human, bird or animal. • Collecting and submitting samples for identification. • Larval identification class.

27. Adult Surveillance • Assist with locating breeding sites after the finding of a positive human, bird or animal.

34. 2003 Mosquito Surveillance • Larval collections around positive West Nile and La Crosse cases. • Test 1,000 mosquito pools at the Southeastern Cooperative Wildlife Disease Study (SCWDS).

35. Full understanding of WNV, it’s prevention and control, is a multidisciplinary challenge-involving such diverse fields as entomology, ecology, poultry science, ornithology, meteorology, the military, epidemiology, public health, pest control, the trade in used tires, race horses, global warming, and risk communication. Cornell Environmental Update, Autumn 2001