Mosquito Reports

Stay up to date on mosquito-borne virus activity within the District. Delta Mosquito and Vector Control District mosquitoes and dead birds for West Nile Virus (WNV), St. Louis Encephalitis Virus (SLEV), and Western Equine Encephalitis Virus (WEEV).

2021 Mosquito-borne Virus Activity in the District

LAST UPDATED: September 10, 2021










2021 Weekly Updates

Activity within the District is updated every Friday. For information about WNV in the entire state of California, please visit

Mosquito Samples

West Nile Virus: 210        St. Louis Encephalitis Virus: 1        Western Equine Encephalitis Virus: 0

There were 39 new WNV and 1 SLEV positive mosquito samples detected the week of September 5th through September 11th. Of these, 31 mosquito samples were collected from Visalia, 8 from Peral, and 1 from Exeter. This is the first SLEV detection in the District for the year. Test results are pending for 51 mosquito samples that were also collected this week. A total of 211 mosquito samples have tested positive from 6 cities and 2 rural areas in the District, out of the 2,017 mosquito samples tested in 2021.

A sample may contain up to 50 individual mosquitoes.


Dead Birds

West Nile Virus: 5         St. Louis Encephalitis Virus: 0         Western Equine Encephalitis Virus: 0

No new dead birds have tested positive for WNV this week.  A total of 5 dead birds have tested positive in the District out of 12 dead birds tested in 2021.

Report dead birds to the WNV call center at 1-877-968-2473. Dead birds may be testable for WNV, SLEV, and WEEV. 


Human Cases

West Nile Virus: 3         St. Louis Encephalitis Virus: 0         Western Equine Encephalitis Virus: 0

There was 1 new human case of WNV reported to Delta MVCD this week. The probable human WNV case reported previously was also confirmed this week. There has been a total of 3 WNV positive human case in the District in 2021.

The Tulare County Public Health Department reports human cases to the District.

Service Request? Get in Touch.


1737 West Houston Ave
Visalia, CA. 93291
Ph. 559-732-8606
TF. 877-732-8606
Fax. 559-732-7441


7:30 AM to 4 PM (excluding holidays)