Home
Public Information and Resources
•  Latest Activity 
•  West Nile Basics 
•  Prevention 
•  Repellent Info 
•  Mosquito Control 
•  Find Your Local Mosquito Control Agency 
Identify and Report Dead Birds
Professional Resources
•  Maps and Data 
•  Educational Materials 
•  Press/Media 
•  Information for Local Agencies 
•  Clinician Info 
•  Veterinarian and Horse Owner Information 
Links
 
Maps and Data > 2004 WNV Activity by County

 

2004 WNV Activity by County

2004 West Nile Activity (Updated 3-18-05)
 
Humans
Horses
Dead Birds
Mosquito Pools*
Sentinel Chickens
State Totals
830
540
3,232
1136
805
Alameda
-
-
23
-
-
Alpine
-
3
3
-
-
Amador
-
-
9
-
-
Butte
7
18
118
1
50
Calaveras
-
-
10
-
-
Colusa
-
6
21
-
-
Contra Costa
-
-
19
-
-
Del Norte
-
-
3
-
-
El Dorado
-
-
22
-
-
Fresno
15
21
116
14
25
Glenn
3
12
75
-
19
Humboldt
-
-
16
-
-
Imperial
1
-
1
32
56
Inyo
-
3
12
-
-
Kern
60
47
87
214
101
Kings
-
1
11
-
2
Lake
1
4
30
17
1
Lassen
1
4
13
-
-
Los Angeles
331
16
840
408
166
Madera
-
-
7
-
-
Marin
-
-
18
-
-
Mariposa
-
-
6
-
-
Mendocino
-
3
13
-
-
Merced
1
3
29
1
-
Modoc
-
-
1
-
-
Mono
-
-
6
-
-
Monterey
-
-
12
-
-
Napa
-
-
6
-
-
Nevada
-
-
26
-
-
Orange
64
2
225
164
3
Placer
1
26
47
4
25
Plumas
-
-
26
-
-
Riverside
116
102
139
104
159
Sacramento
3
84
153
21
16
San Benito
-
-
5
-
-
San Bernardino
197
36
289
128
104
San Diego
2
2
34
-
-
San Francisco
-
-
14
-
-
San Joaquin
3
19
57
2
11
San Luis Obispo
1
-
15
1
-
San Mateo
-
-
15
-
-
Santa Barbara
-
-
7
-
-
Santa Clara
1
-
46
-
4
Santa Cruz
-
-
36
-
-
Shasta
6
30
90
11
5
Sierra
-
-
3
-
-
Siskiyou
-
5
34
-
-
Solano
-
1
17
-
-
Sonoma
-
1
49
-
-
Stanislaus
-
7
82
3
12
Sutter
-
11
28
8
12
Tehama
10
44
115
-
12
Trinity
-
1
9
-
-
Tulare
3
13
48
3
11
Tuolumne
-
-
34
-
-
Ventura
2
3
23
-
1
Yolo
1
1
26
-
10
Yuba
-
11
13
-
-

* A mosquito pool is a collection of approximately 50 mosquitoes that are tested together for West Nile virus.

Quick Links