West Nile Virus Activity in California...

West Nile Virus West Nile Virus Activity in Activity in California California

20052005

Division of Communicable Disease ControlCalifornia Department of Health Services

WNV in California, 2003WNV in California, 2003

Equine Case (1)

Human Case (3)

32 10,111

70 31,227

96 1,769

POS N

20042004

58 counties

WNV activity (no human cases)

WNV activity (number of human infections)

Humans 830 / 28 Horses 540 / 230Dead birds 3232Mosquito pools 1136Sentinel chickens 805

15

1

197

116

331

60

7

1

6

3

64

2

2

1

1

10

1 1

33

1

1

3

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7

Sequence of WNV detection events in California Sequence of WNV detection events in California relative to human caserelative to human case onset, 2005 onset, 2005

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov

Num

ber o

f cas

es

1/3

1/25

2/15

3/15*5/1

Week of onset• Onset dates not available for all patients• Birds, mosquitoes: date of collection• Chickens: date of probable seroconversion * Estimated date of onset

March 2005March 20051 / 005711

Humans, onset / reportedHorses, onset / reportedDead birdsMosquito poolsSentinel chickens

N = 1 county with human infection

WNV activity (number of human cases with known onset date)


1

April 2005April 20052 / 006311


N = 2 counties with human infection



1

1

May 2005May 20054 / 01 / 110163





1

1

1

1

June 30, 2005June 30, 2005




2

5

3

8

1

1

11

22/ 28 / 343713714


July 31, 2005July 31, 2005




30

41

44

24

15

8

1418

5

4

8

21

22

6

11

31

21

254 / 56116 / 481,216588179


12

1

August 31, 2005August 31, 2005




49

79

140

44

26

21

3426

22

12

28

274

64

9

16128

83

8

1

2

1

2

1

2

11

1

656 / 416343 / 2772,3061,040557


7

1

1

5

WNV Activity in California WNV Activity in California 20052005

WNV activity (number of human infections)


67

104

177

60

35

25

6332

47

17

35

365

92

9

281

211

195

12

1

4

1

2

1

4

12

1

19294563,0461,242790

Humans infectionsHorse casesDead birdsMosquito poolsSentinel chickens


4

13

1

1

2

1

1

6

2005 2005 Reported WNV Reported WNV

cases per cases per 100,000 people100,000 people

CA Total 2.6

Glenn 49.1Kings 24.7Stanislaus 19.6 > 15Tulare 15.2

Sacramento 14.2Placer 14.0Merced 13.3Butte 11.8 > 10 Sutter 11.4Amador 11.4Colusa 10.6 Yuba 10.0

Madera 9.8Kern 9.5Fresno 7.6Yolo 7.1 > 5San Joaquin 6.4Riverside 6.4Tehama 7.1

Calaveras 4.9Plumas 4.8Nevada 4.3San Bernardino 1.9 > 1Tuolumne 1.8Solano 1.3Contra Costa 1.2

Others > 0

Human infections 929

Top Ten Counties with Human WNV InfectionsTop Ten Counties with Human WNV Infections

2004 2005Sacramento 177

Riverside 104Stanislaus 92

Kern 67Fresno 63Tulare 60

Los Angeles 47San Joaquin 36

Placer 35San Bernardino 35

Los Angeles 323San Bernardino 191

Riverside 112Orange 64

Kern 60Fresno 15Tehama 10

Butte 7Shasta 6Glenn 3

Human WNV Infections Human WNV Infections 2004 2004 -- 20052005

Human infections 830 929

Counties 23 40

Positive blood donors 66 93

Symptomatic donors 15 (23%) 42 (45%)

2004 2005

Human WNV Clinical Presentation Human WNV Clinical Presentation 2004 2004 -- 20052005

Number of symptomatic cases 779 874

Clinical presentation

Neuroinvasive 289 (42%) 303 (36%)

Fever 395 (58%) 530 (64%)

Unknown 95 41

Median age 52 yrs 51 yrs

Fatal cases 28 18

Median age of fatalities 76 yrs 79 yrs

2004 2005

Incidence of WNV illness by age and clinical presentationIncidence of WNV illness by age and clinical presentationCalifornia 2005California 2005

(n=818)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70+Age group (years)

Rep

orte

d in

cide

nce

per 1

00,0

00 p

op.

WNNDWNF

0

20

40

60

80

100

120

140

9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7

WNNDWNFUnk

Mar Apr May Jun Jul Aug Sep Oct Nov

• Onset dates not available for all patientsWeek of onset

Num

ber o

f cas

es

* Estimated date of onset

Human WNV Cases in California, 2005Human WNV Cases in California, 2005

5-M

ar

19-M

ar

2-A

pr

16-A

pr

30-A

pr

14-M

ay

28-M

ay

11-J

un

25-J

un

9-Ju

l

23-J

ul

6-A

ug

20-A

ug

3-Se

p

17-S

ep

1-O

ct

15-O

ct

29-O

ct

12-N

ov

26-N

ov

Mar 15 Nov 11

0

20

40

60

80

100

120

140

160

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

2005

2004

Onset of Human Illness 2004 Onset of Human Illness 2004 -- 200520055-

Mar

19-M

ar

2-A

pr

16-A

pr

30-A

pr

14-M

ay

28-M

ay

11-J

un

25-J

un

9-Ju

l

23-J

ul

6-A

ug

20-A

ug

3-Se

p

17-S

ep

1-O

ct

15-O

ct

29-O

ct

12-N

ov

26-N

ov

Week of onset

Num

ber o

f cas

es

Dead Bird SurveillanceDead Bird Surveillance

Dead Bird Surveillance Program Dead Bird Surveillance Program 2000 2000 -- 20052005

Year Reported Tested Positive

2000 40 20 0

2001 68 18 0

2002 3,666 653 0

2003 8,650 1,765 96

2004 93,057 5,728 3,2322005 109,375 9,263 3,046

Prevalence of WNV in Tested Prevalence of WNV in Tested Dead Birds*, 2005Dead Birds*, 2005

No positive birds

1 – 19 %

20 –39 %

40 – 59 %

60 – 79 %

* Prevalence = (# pos birds / # tested birds) x 100

2005: 92 species of WNV positive dead birds2005: 92 species of WNV positive dead birds

Other Corvids (4 species) 1%

Non-Corvids (85 species)16%

American Crow 44%

Western Scrub Jay 27%

Yellow-billed Magpie 12%

Number reported = 109,375Number tested = 9,263 Number WNV pos = 3,046

50

0

5

10

15

20

25

30

35

40

45

Feb Mar April May June July Aug Sep Oct Nov

House FinchHouse SparrowAmerican RobinRed-Tailed HawkLesser GoldfinchNorthern Mockingbird

Top 6 WNV Positive NonTop 6 WNV Positive Non--Corvids, 2005Corvids, 2005

WNV Positive Corvids and NonWNV Positive Corvids and Non--Corvids Corvids JanuaryJanuary--AprilApril

2004 2005

Non-corvids 7%

Corvids 93% Non-Corvids 73%

Corvids 27%

Dead Birds Reported Dead Birds Reported 20052005

n = 109,375

DYCAST* Human WNV Risk Modeling SystemDYCAST* Human WNV Risk Modeling System

DYCAST in 200583% accuracy in predictinghuman cases with quarter-square mile resolution (cells)

50% of cases occurred in cells identified as high risk approximately one monthprior to case onset

Used to evaluate efficacy of aerial adulticiding in Sacramento County

* Dynamic Continuous-Area Space-Time

WNV in California WNV in California Tree Squirrels Tree Squirrels -- 20052005

First positive squirrel: June 10, 2005• Placer County

Prevalence (PCR) was 27% (48 / 180)

Similar prevalence in dead birds (35%)

WNV Activity in Mosquitoes in 2005 WNV Activity in Mosquitoes in 2005

WNV Activity in Mosquitoes WNV Activity in Mosquitoes number positive poolsnumber positive pools

0

20

40

60

80

100

120

140

160

5/5

5/1

9

6/2

6/1

6

6/3

0

7/1

4

7/2

8

8/1

1

8/2

5

9/8

9/2

2

10/6

10/2

0

11/3

11/1

7

12/1

Date

Posi

tive

Pools 2004

2005

2004 1,136 pos (14,602)2005 1,242 pos (21,402)

WNV Positive Mosquito SpeciesWNV Positive Mosquito Species1,242 pos. pools / 21,402 mosquitoes tested

Culexquinquefasciatus 476 (38%)tarsalis 460 (37%)pipiens 240 (19%)stigmatosoma 33 (2.7%)erythrothorax 26 (2.1%)thriambus 7 (<1%)

Plus Anopheles freeborni (1)

0.42

3.23

4.05

4.61

4.83

5.82

0 1 2 3 4 5 6 7

Cx. erythrothorax

Cx. tarsalis

Cx. thriambus

Cx. pipiens

Cx.quinquefasciatus

Cx. stigmatosoma 596 pools tested

6054 pools tested

2519 pools tested

98 pools tested

7688 pools tested

2088 pools tested

Minimum Infection Rate (MIR)** MIR = (# positive mosquito pools / total number of mosquitoes tested) X 1,000

Minimum Infection Rates (per 1,000) by Species Minimum Infection Rates (per 1,000) by Species July July -- September 2005September 2005

> 4.0

> 2.0

> 1.0

> 0.1

SacramentoPlacerFresnoTulareYubaMaderaYoloStanislausButteSutterLakeGlennKernSan BernardinoLos AngelesVenturaKingsSan Luis ObispoSanta ClaraMercedOrangeImperialRiversideSan JoaquinSolanoAlamedaInyoContra CostaNo positive poolsNo mosquitoes tested

7.35.94.94.54.44.33.73.62.82.72.42.42.01.91.71.71.51.51.41.21.00.80.80.80.60.50.30.10

Minimum Minimum Infection Rate Infection Rate

(MIR)* (MIR)* Counties Counties

Submitting Submitting Mosquitoes Mosquitoes

20052005

* MIR = (# positive mosquito pools/total number of mosquitoes tested) X 1,000

Includes all species of mosquitoes

WNV Activity in Sentinel WNV Activity in Sentinel Chickens in 2005Chickens in 2005

Sentinel Chicken Sentinel Chicken Surveillance Program Surveillance Program

20052005WNV positive flock Negative flock

• 790 seroconversions• 31 counties• 141 / 271 flocks

WNV Activity in Sentinel Chickens WNV Activity in Sentinel Chickens

2004: 811+ (32,616) 2005: 790+ (34,011)

0

20

40

60

80

100

120

140

160

5/5

5/1

9

6/2

6/1

6

6/3

0

7/1

4

7/2

8

8/1

1

8/2

5

9/8

9/2

2

10/6

10/2

0

11/3

11/1

7

12/1

12/1

5

12/2

9

Date

Posi

tive

Chic

kens

2004

2005

2004 811 pos (143 / 231 flocks) 2005 790 pos (141 / 253 flocks)

Equine WNV Equine WNV SurveillanceSurveillance

20052005

456 cases 1,295 tested

(40 positive counties)

2004: 540 cases

http://www.cdfa.ca.gov/

2005 Equine WNV Data2005 Equine WNV Data456 WNV infected horses (40 counties)200 (44%) died / euthanizedVaccination status

20 properly vaccinated78 improperly vaccinated342 non-vaccinated

Median age: 13 years (4 mos – 40 years)

0

10

20

30

40

50

60

70

22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

Week of Onset for Equine WNV CasesWeek of Onset for Equine WNV CasesCalifornia, 2005California, 2005

Week of onset

Num

ber o

f cas

es

4-Ju

n

18-J

un

2-Ju

l

16-J

ul

30-J

ul

13-A

ug

27-A

ug

10-S

ep

24-S

ep

8-O

ct

22-O

ct

5-N

ov

19-N

ov

3-D

ec

May 1 Nov 25

WNV Team at DHSWNV Team at DHSDIS

Jon RosenbergVPHS

Ben SunJames GloverClaudia Erickson

VRDLCarol GlaserCynthia JeanCindi CossenLiz BaylisShilpa Gavali

OPALea Brooks

VBDSVicki KramerStan HustedAl HomRyan CarneyKerry PadgettLauren MarcusColleen BarclayAnne KjemtrupMark NovakRenjie HuHotline staffRegional biologists

CollaboratorsCollaborators

Local Health DepartmentsLocal Public Health Laboratories

Environmental Health Departments

http://mvcac.org/

http://vector.ucdavis.edu/surveillance/default.html

http://www.cdfa.ca.gov/

West Nile Virus Activity in California...

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