West Nile Virus Activity 2021
West Nile virus Facts
- West Nile virus is the most common mosquito-borne disease that affect residents in Los Angeles County
- Public health agencies detect West Nile virus every year in L.A. County. This means the virus is found naturally in our city environments, which means it's endemic.
- Our agency uses routine traps to colect samples of mosquitoes. The mosquito samples are tested for a mosquito-borne diseases, such as West Nile virus. In addition, dead birds, which can carry West Nile virus, are submitted for testing.
Our agency reports data related to mosquitoes. Human cases are reported by the L.A. County Department of Public Health and Pasadena Health Department.
2021 West Nile Virus Activity
Last update: 10/22/2021
West Nile Virus Positive Mosquito Samples
A sample is a random collection of 10-50 mosquitoes from a trap. Positive mosquito samples from routine and randomized trapping provide insight into of the spread of West Nile virus.
| City/Community | Number of WNV+ Mosquito Samples | Date of first report |
|---|---|---|
| Alhambra | 10 | 8/6 |
| Arcadia | 4 | 9/13 |
| Azusa | 9 | 7/22 |
| Baldwin Park | 10 | 7/22 |
| Claremont | 1 | 8/6 |
| Covina | 23 | 6/28 |
| Duarte | 1 | 7/22 |
| El Monte | 2 | 10/4 |
| Glendora | 11 | 7/12 |
| Industry | 2 | 8/12 |
| Irwindale | 5 | 7/12 |
| La Puente | 4 | 8/27 |
| La Verne | 6 | 7/30 |
| Monrovia | 1 | 9/20 |
| Monterey Park | 2 | 9/20 |
| Pasadena | 10 | 7/22 |
| Pomona | 3 | 9/2 |
| Rosemead | 7 | 7/30 |
| San Dimas | 14 | 7/19 |
| San Gabriel | 4 | 9/20 |
| South Pasadena | 11 | 7/19 |
| Temple City | 5 | 8/27 |
| Unincorporated LA County (Charter Oak) | 2 | 10/4 |
| Unincorporated LA County (Mayflower Village) | 2 | 10/4 |
| Unincorporated LA County (Vincent neighborhood) | 6 | 6/21 |
| Unincorporated LA County (West Puente Valley neighborhood) | 2 | 7/12 |
| Walnut | 8 | 7/22 |
| West Covina | 25 | 6/21 |
| TOTAL | 190 | -- |
West Nile Virus Positive Dead Birds
People report dead birds they observe in their community. Positive dead birds are an indication West Nile virus is widespread in the region.
| City/Community | Number of WNV+ dead birds | Date of first report |
|---|---|---|
| Baldwin Park | 1 | 8/12 |
| Covina | 13 | 6/21 |
| Duarte | 1 | 8/27 |
| Glendora | 3 | 7/19 |
| Pasadena | 2 | 10/4 |
| Pomona | 1 | 8/6 |
| Sierra Madre | 1 | 9/13 |
| South Pasadena | 4 | 6/7 |
| West Covina | 7 | 7/19 |
| TOTAL | 33 | -- |
