# Presentation: 227605

## West Nile VirusIn Arizona

- Craig Levy
- Arizona Department of Health Services
- Vector-Borne Diseases Program
- (602) 364-4562   _[levyc@azdhs.gov](mailto:levyc@azdhs.gov)_

## WNV Outbreak Potential

- Culex tarsalis and Cx. quinq = common
- Certain bird reservoirs = common
- Long arbovirus transmission season
- Susceptible human population
- SLE = seasonal occurrence in many areas
- Effects of urbanization –“tropicalization”
- Thousands of green swimming pools

## Slide 3

## Got Desert ?

## How about a refreshing dip?

## WNV Surveillance in AZ

- Human case F/U
- Mosquito pools
- Dead bird testing
- Equine case F/U
- Sentinel chickens
- Other animals

## Human Case Surveillance

- WNV is reportable by MDs and Labs
- Enhanced passive surveillance
- Switch to active surveillance w/ WNV+
- AZ State Lab - IgM ELISA:  WNV & SLE
- Priority testing - neuroinvasive &/or hosp.
- Confirmation back-up by CDC
- Validated commercial lab + results during the first two months

## WNV Human Cases 2004

- Total # cases = 391        Fatal = 15
- Age range: 1 month – 98 years, Med.=51
- Clinical presentation:
-          ►  Meningitis:    105 (26.9%)
-          ►  Encephalitis:  109 (27.9%)
-          ►  WNV Fever:   160 (40.9%)
-          ►  AFP:               2 (0.5%)
-          ►  Unknown:      15 (3.8%)

## Arbovirus Cases 2004

- Total # neuro invasive cases = 214
- Est. # clinical WNV infections:  4,000+
- Surveillance detected ~ 10% clinical cases
- Est. # asymptomatic infections:  17,000+
- SLE:  4   (Maricopa – 3, Mohave – 1)

## Slide 10

## WNV Cases by County / Rate

| COUNTY | Population | #Cases (fatal) | Rate/100,000 |
| --- | --- | --- | --- |
| Apache | 69,243 |       5 |      7.25 |
| Cochise | 117,755 |       1 |      0.85 |
| Coconino | 116,320 |       0  |      0.00 |
| Gila | 51,335 |       1 |      1.95 |
| Graham | 33,489 |       4 |      12.00 |
| Greenlee | 8,547 |       0 |       0.00 |
| LaPaz | 19,715 |       0 |       0.00 |
| Maricopa | 3,072,149 |     355  (13)   |      11.56 |

## WNV Cases by County/Rate (Cont).

| County | Population | #Cases (fatal) | Rate/100,000 |
| --- | --- | --- | --- |
| Mohave | 155,032 |        6 |     3.87 |
| Navajo | 97,470 |        1  (1) |     1.02 |
| Pima | 843,746 |        7  (1) |      0.83 |
| Pinal | 179,727 |        9  |      5.00 |
| Santa Cruz | 38,381 |        0 |      0.00 |
| Yavapai | 167,517 |        1 |      0.60 |
| Yuma | 160,026 |        1* |      0.63 |
| State Total | 5,130,452 |       391 |      7.62 |

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## Viremic Blood Donors

- Viremic donors:  Total = 36
- Viremic donors w/ sx:  24
- Viremic donors no sx: 12
- One case of TAT - fatal
- WNV+ organ donor:  1

## Mosquito Pool Surveillance

- Testing performed by:
-    -Arizona State Health Lab  -  PCR ~  3,100 pools
-     -Yuma Co. Pest Abatement Dist. – RAMP ~ 280 pools
-     -Aquatic Consulting & Testing – RAMP ~ 950 pools
-     -U.S. Army – CHPPM – PCR  ~ 140 pools
- Total pools tested ~ 4,470
- 12 species / 6 genera
- WNV + = 250 pools  (5.6%)

## WNV+ Mosquito Pools / County

- Apache ......8
- Cochise......6
- Coconino....0
- Gila............1
- Graham......6
- Greenlee.....0
- La Paz .......14
- Maricopa...101

- Mohave ........5
- Navajo ........10
- Pima............29
- Pinal.............9
- Santa Cruz ...0
- Yavapai........16
- Yuma ...........43

## WNV+ Mosquito Species

- Culex tarsalis ................157
- Culex quinquefasciatus ....73
- Culex erythrothorax...........4
- Culex sp. ......................12
- Psorophora columbaie.......2
- Ochlerotatus nigromaculis...1

## “Ms. Skeeter”

- Apache County
- Fight-the-Bite
- Mascot

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## Dead Bird Surveillance

- Testing performed by the UA-Veterinary Diagnostic Laboratory, Tucson
- Tests: IHC, PCR, and RAMP assay
- All bird species were accepted so long as they were “fresh”
- Approx. 730 birds were tested in 2004
- 98 birds (13.4%) were WNV+

## Wild Birds - WNV+

- Sparrows ........30
- Kestrels............9
- Scrub Jays........8
- House Finches...5
- Ravens.............4
- Cactus Wrens.....3
- Burrowing Owls...3
- Great Horned ......2
- Blk Crown Heron...2

- Crows...........2
- Doves...........2
- Thrush..........2
- Elf Owl..........1
- Golden Eagle...1
- Redtail Hawk....1
- Merlin..............1
- Quail...............1

## Pet/Exotic Birds – WNV+

- Canaries...........5
- Gould Finches....3
- Lorikeets...........2
- Amazon Parrot...1
- Cockatiel..........1
- Grasskeet.........1
- Mynah..............1
- Sun Conure.......1

## WNV+ Birds by County

- Apache........2
- Cochise.......2
- Coconino.....3
- Gila............0
- Graham.......3
- Greenlee......0
- La Paz.........1
- Maricopa....52

- Mohave.........1
- Navajo..........5
- Pima............17
- Pinal.............1
- Santa Cruz.....1
- Yavapai......10
- Yuma...........0

## Dead Bird Surveillance

- Dead bird testing was of limited surveillance value in AZ due to sparce populations of Corvids
- Dead sparrows were best WNV indicators
- Scrub jays were good indicators in certain northern counties
- Human cases were reported before +birds

## Equine Case Surveillance

- Horse bloods were tested by UA-VDL
- Test = IgM ELISA,  IHC & PCR on Tissues
- Approx. 330 horses were tested
- 109  (33%) horses were WNV+

## Equine Cases by County

- Apache ..........10
- Cochise...........1
- Coconino.........6
- Gila.................2
- Graham............2
- Greenlee..........0
- La Paz.............0
- Maricopa.........55

- Mohave..........1
- Navajo............5
- Pima............13
- Pinal..............7
- Santa Cruz......0
- Yavapai...........7
- Yuma..............0

## Sentinel Chicken Surveillance

- 19 flocks in 8 counties
- 6-10 birds / flock
- bled every 2 weeks
- IgG IFA*– AZ State Lab
- 50 chickens seroconv.
-    in 12 flocks / 5 counties

## Other Animal Surveillance

- UA-VDL: IHC, PCR
- 21 animals tested: 12 sp. (5 wild,7 exotic)
- 5 animals tested WNV+
- 4 tree squirrels & 1 alpaca

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## Lessons & Conclusion, Part 1 

- Don’t make predictions!
- Start surveillance earlier (March)
- Mosquito pool surveillance = best overall
- Dramatic WNV outbreaks can occur even when vector numbers are low
- Dead bird surveillance does not work well where Corvid species are uncommon

## Lessons & Conclusions, Part 2

- Absence of Corvid bird reservoirs does not  prevent WNV outbreaks
- Blood screening - start NAT testing on individual bloods earlier
- Don’t use IgM assay for testing chicken bloods (IgM is short-lived)

## Acknowledgments / Thanks!

- Arizona Dept. Health
-   -  State Health Lab
-   -  Other Epi staff
-   -  Bioterrorism staff
-   -  Vector/Zoonotic staff

- County Health Depts
- Indian Health Service
- Indian Tribes
- CDC – Ft. Collins
- Yuma Co. Pest Abate. Dist.
- UA Vet. Diag. Lab
- Aquatic Consulting
- US Army – CHPPM
- Air Force
- Blood Systems
- Univ. of Arizona
- Chinle Veterinary Clinic