# Presentation: 153681

## West Nile Virus Activity in California   2005

**Vicki Kramer, Ph.D.**
**Vector-Borne Disease Section**
**California Department of Health Services**

## VBDS
Stan Husted
Al Hom
Ryan Carney
Kerry Padgett
Lauren Marcus
Colleen Barclay
Anne Kjemtrup
Mark Novak
Renjie Hu
Hotline staff
Regional biologists

**Stan Husted**
**Al Hom**
**Ryan Carney**
**Kerry Padgett**
**Lauren Marcus**
**Colleen Barclay**
**Anne Kjemtrup**
**Mark Novak**
**Renjie Hu**
**Hotline staff**
**Regional biologists**

**DIS**
**Jon Rosenberg**
**VPHS**
**Ben Sun**
**James Glover**
**Claudia Erickson**
**VRDL**
**Carol Glaser**
**Cynthia Jean**
**Cindi Cossen**
**Liz Baylis**
**Shilpa Gavali**
**OPA**
**Lea Brooks**

**WNV Team at DHS**

## Collaborators

** ****Local Health Departments**
** ****Local Public Health Laboratories**
** ****Environmental Health Departments**

**Collaborators**

## WNV in California, 2003

**WNV in California, 2003**

**Equine Case (1)**

**Human Case (3)**

**32  ****10,111**

**70  ****31,227**** **

**96   ****1,769**

**POS**

**N**

## 2004

**2004**

**WNV ****a****ctivity (number of human infections)**

**WNV ****a****ctivity (no human cases)**

**58 counties**

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

**15**

**1**

**197**

**116**

**331**

**60**

**7**

**1**

**6**

**3**

**64**

**2**

**2**

**1**

**1**

**10**

**1**

**1**

**3**

**3**

**1**

**1**

**3**

## Sequence of WNV detection events in California 

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

-  Onset dates not available for all patients
-  Birds, mosquitoes: date of collection
-  Chickens: date of probable seroconversion

**Week of onset**

**Number of cases**

**1/3**

**1/25**

**2/15**

**3/15*******

**5/1**

- * Estimated date of onset

## March 2005

**March 2005**

**1 ****/ 0**
**0**
**57**
**1**
**1**

**Humans, onset**** / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**N = 1 county with human infection**

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

**WNV activity (no human cases)**

**1**

## April 2005

**April 2005**

**2**** ****/ 0**
**0**
**63**
**1**
**1**

**Humans, onset / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**N = 2 counties with human infection**

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

**WNV activity (no human cases)**

**1**

**1**

## May 2005

**May 2005**

**4 / 0**
**1 / 1**
**101**
**6**
**3**

**Humans, onset / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**N = 4 counties with human infection**

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

**WNV activity (no human cases)**

**1**

**1**

**1**

**1**

## June 30, 2005

**N = 8 counties with human infection**

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

**WNV activity (no human cases)**

**2**

**5**

**3**

**8**

**1**

**1**

**1**

**1**

**22/ 2**
**8 / 3**
**437**
**137**
**14**

**Humans, onset / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

## July 31, 2005

**N = 24 counties with human infection**

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

**WNV activity (no human cases)**

**30**

**41**

**44**

**24**

**15**

**8**

**14**

**18**

**5**

**4**

**8**

**2**

**1**

**22**

**6**

**1**

**1**

**3**

**1**

**2**

**1**

**254 / 56**
**116 / 48**
**1,216**
**588**
**179**

**Humans, onset / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**1**

**2**

**1**

## August 31, 2005

**N = 37 counties with human infection**

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

**WNV activity (no human cases)**

**49**

**79**

**140**

**44**

**26**

**21**

**34**

**26**

**22**

**12**

**28**

**27**

**4**

**64**

**9**

**16**

**1**

**2**

**8**

**8**

**3**

**8**

**1**

**2**

**1**

**2**

**1**

**2**

**1**

**1**

**1**

**656 / 416**
**343 / 277**
**2,306**
**1,040**
**557**

**Humans, onset / reported**
**Horses, onset / reported**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**7**

**1**

**1**

**5**

## WNV Activity in California 2005

**WNV activity (number of human infections)**

**WNV activity (no human cases)**

**68**

**104**

**177**

**60**

**34**

**25**

**63**

**32**

**47**

**17**

**35**

**36**

**5**

**92**

**9**

**28**

**1**

**2**

**11**

**19**

**5**

**12**

**1**

**4**

**1**

**2**

**1**

**4**

**1**

**2**

**1**

**1**

**928**
**456**
**3,046**
**1,242**
**790**

**Humans infections**
**Horse cases**
**Dead birds**
**Mosquito pools**
**Sentinel chickens**

**N = 40 counties with human infection**

**4**

**13**

**1**

**1**

**2**

**1**

**1**

**6**

## 2005 

**Reported WNV cases per 100,000 people****     **
**CA Total    **
**2.6**

**Glenn****	****      49.1****	**
**Kings****	****      24.7**
**Stanislaus****	****      19.6  ****	****     **_**>**_** 15**
**Tulare****	****      15.2**
**Sacramento    14.2**
**Placer****	****      14.0**
**Merced****	****      13.3**
**Butte****	****      11.8****	****    **_**>**_** 10 ****	**
**Sutter****	****      11.4**
**Amador****	****      11.4****	**
**Colusa****	****      10.6    ****	**
**Yuba****	****      10.0**
**Madera****	****        9.8****	**** **
**Kern****	****        9.5**
**Fresno****	****        7.6****	**
**Yolo****	****        7.1****	****    **_**>**_** 5**
**San Joaquin     6.4****	**
**Riverside****	****        6.4****	****    **
**Tehama****	****        7.1**
**Calaveras****	****        4.9**
**Plumas****	****        4.8**
**Nevada****	****        4.3**
**San Bernardino  1.9****	****    **_**>**_** 1**
**Tuolumne         1.8**
**Solano****	****        1.3**
**Contra Costa    1.2**
**Others ****	****                       > 0**

**Human infections   928**
**	****  **

## 2005

| Sacramento | 177 |
| --- | --- |
| Riverside | 104 |
| Stanislaus | 92 |
| Kern | 67 |
| Fresno | 63 |
| Tulare | 60 |
| Los Angeles | 47 |
| San Joaquin | 36 |
| Placer | 35 |
| San Bernardino | 34 |

| Los Angeles | 323 |
| --- | --- |
| San Bernardino | 191 |
| Riverside | 112 |
| Orange | 64 |
| Kern | 60 |
| Fresno | 15 |
| Tehama | 10 |
| Butte | 7 |
| Shasta | 6 |
| Glenn | 3 |

**Top Ten Counties with Human WNV Infections**

**2005**

**2004**

## Human WNV Infections 2004 - 2005

| Human infections | 830 | 928 |
| --- | --- | --- |
| Counties | 23 | 40 |
| Positive blood donors | 66 | 93 |
| Symptomatic donors | 15 (23%) | 42 (45%) |

**2004**

**2005**

## Human WNV Clinical Presentation 2004 - 2005

| Number of symptomatic cases | 779 | 873  |
| --- | --- | --- |
|            Clinical presentation |  |  |
|                       Neuroinvasive | 289 (42%) | 301 (36%) |
| 	           Fever | 395 (58%) | 524 (64%) |
| 	           Unknown | 95 | 48 |
| 	Median age | 52 yrs | 51 yrs |
|            Fatal cases | 28 | 18 |
| 	Median age of fatalities | 76 yrs | 79 yrs |

**Human WNV Clinical Presentation ****2004 - 2005**

**2004**

**2005**

## Incidence of WNV illness by age and clinical presentation

**California 2005**

**(n=818)**

## Human WNV Cases in California, 2005

-  Onset dates not available for all patients

**Week of onset**

**Number of cases**

- * Estimated date of onset

**Human WNV Cases in California, 2005**

**5-Mar**
**19-Mar**
**2-Apr**
**16-Apr**
**30-Apr**
**14-May**
**28-May**
**11-Jun**
**25-Jun**
**9-Jul**
**23-Jul**
**6-Aug**
**20-Aug**
**3-Sep**
**17-Sep**
**1-Oct**
**15-Oct**
**29-Oct**
**12-Nov**
**26-Nov**

**Mar 15**

**Nov 11**

## Onset of Human Illness 2004 - 2005

**Onset of Human Illness 2004 - 2005**

**5-Mar**
**19-Mar**
**2-Apr**
**16-Apr**
**30-Apr**
**14-May**
**28-May**
**11-Jun**
**25-Jun**
**9-Jul**
**23-Jul**
**6-Aug**
**20-Aug**
**3-Sep**
**17-Sep**
**1-Oct**
**15-Oct**
**29-Oct**
**12-Nov**
**26-Nov**

**Week of onset**

**Number of cases**

## Dead Bird Surveillance

**Dead Bird Surveillance**

## Dead Bird Surveillance Program 2000 - 2005

| 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 | 3,232 |
| 2005 | 109,375 | 9,263 | 3,046 |

## Prevalence of WNV in Tested Dead 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 birds

**2005:  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%**

## Top 6 WNV Positive Non-Corvids, 2005

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

## WNV Positive Corvids and Non-Corvids 

**2004**

**WNV Positive Corvids and Non-Corvids **
**January-April**

**2005**

**Non-corvids 7%**

**Corvids 93%**

**Non-Corvids 73%**

**Corvids 27%**

## Dead Birds Reported 

**Dead Birds Reported **
**2005**
**n = 109,375**

## DYCAST* Human WNV Risk Modeling System

**DYCAST in 2005**
**83% accuracy in predicting**** human cases with quarter-square mile resolution (cells)**
**50%**** ****of cases**** occurred in cells identified as high risk approximately ****one month**** prior to case onset**
**Used to evaluate efficacy of ****aerial adulticiding**** in Sacramento County**

**DYCAST* Human WNV Risk Modeling System**

*** Dynamic Continuous-Area Space-Time**

## WNV in California Tree Squirrels - 2005

**Placer County**
**Prevalence (PCR) was 27% (48 / 180)**
**Similar prevalence in dead birds (35%)**** **

**WNV in California ****Tree Squirrels - 2005**

## WNV Activity in Mosquitoes in 2005 

## WNV Activity in Mosquitoes number positive pools

**WNV Activity in Mosquitoes ****number positive pools**

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

## WNV Positive Mosquito Species

**1,242 pos. pools / 21,402 mosquitoes tested**

***Culex***
***quinquefasciatus*****	****   476   (38%)**
***tarsalis*****	****	****	****   460****	****   (37%)**
***pipiens*****	****	****	****   240****	****   (19%)**
***stigmatosoma*****	****   33     (2.7%)**
***erythrothorax*****	****   26     (2.1%)**
***thriambus*****	****	****   7       (<1%)**
**Plus *****Anopheles freeborni***** (1) **

## Minimum Infection Rates (per 1,000) by Species 

**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 **
**July - September 2005**

## Minimum Infection Rate (MIR)*  

**Counties Submitting Mosquitoes **
**2005**

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

## WNV Activity in Sentinel Chickens in 2005

## Sentinel Chicken 

**  **

**Negative flock**** **

**WNV positive flock **

**Sentinel Chicken **
**Surveillance Program **
**2005**

** ****790 seroconversions**
** ****31 counties**
** ****141 / 253 flocks    ****	**

## WNV Activity in Sentinel Chickens 

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

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

##  Equine WNV Surveillance

** ****Equine WNV Surveillance**
**2005**
**456 cases  **
**1,295 tested**
**(40 positive counties)**

**2004: 540 cases**

## 2005 Equine WNV Data

**200 (44%) died / euthanized**
**Vaccination status**
**20 properly vaccinated**
**78 improperly vaccinated**
**342 non-vaccinated**
**Median age:  13 years (4 mos – 40 years)**** **

**2005 Equine WNV Data**

## Week of Onset for Equine WNV CasesCalifornia, 2005

**Week of Onset for Equine WNV Cases****California, 2005**

**Week of onset**

**Number of cases**

**4-Jun**
**18-Jun**
**2-Jul**
**16-Jul**
**30-Jul**
**13-Aug**
**27-Aug**
**10-Sep**
**24-Sep**
**8-Oct**
**22-Oct**
**5-Nov**
**19-Nov**
**3-Dec**

**May 1**

**Nov 25**

## $12 million appropriated in state budget to enhance and expand mosquito control

**By July 26, 2005, initial applications from local agencies had been reviewed and $9.0 million awarded to 75 local agencies**
**Through December 2005, $10.7 million had been awarded to 81 agencies in 47 of California’s 58 counties**
**In 2006, the remaining $1.0 million will be awarded for early season mosquito control**

## We’re hoping for a quieter year in 2006!

**We’re hoping for a quieter year in 2006!**

## Related Posters by DHS Staff

**Barclay:****  ****WNV in wild birds: Temporal difference in species impact**
**Carney:****  ****Utilizing the spatiotemporal DYCAST risk modeling system to predict human WNV cases in CA**
**Erickson:****  ****WNV education in California: Regional perspectives**** **
**Gavali:****  ****West Nile encephalitis outcomes**
**Kjemtrup:  ****Long-term health effects of WNV fever patients in California: 2004 results and initial results for 2005-2006**
**Marcus:****  ****West Nile virus in California 2004-2005**
**Patiris:****  ****Serological time-course investigation of flavivirus inoculated**** chickens**