Mosquito Reports

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

2023 Mosquito-borne Virus Activity in the District

LAST UPDATED: October 17, 2023










2023 Weekly Updates

Dead birds can be reported online at Report a Dead Bird all year or directly to the District at 559-732-8606. For information about WNV in the entire state of California or all of Tulare County, please visit

Mosquito Samples

West Nile Virus: 515*    St. Louis Encephalitis Virus: 203*    Western Equine Encephalitis Virus: 0

There was a total of 1 new West Nile virus positive mosquito sample and 5 St. Louis encephalitis virus positive mosquito samples from Visalia and Exeter. There have been a total of 468 West Nile virus positive, 157 St. Louis encephalitis virus positive, and 47 West Nile virus and St. Louis encephalitis virus positive mosquito samples out of 6,798 samples tested so far in 2023. Positive samples have been collected from Calgro, Cutler, Delft Colony, Dinuba, Exeter, Farmersville, Goshen, Ivanhoe, Orosi, Peral, Sequoia Fields, Seville, South Kings River, Traver, Visalia, and Woodlake.

*Includes 47 mosquito samples with WNV/SLEV co-infection.

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

There were 0 new WNV positive dead birds this week. Positive birds have been collected from Exeter and Visalia. A total of 5 dead birds have tested positive for WNV out of 12 dead birds tested so far in 2023.

Report dead birds to the WNV call center at 1-877-968-2473, online at, or directly to the District at 559-732-8606. Dead birds may be testable for WNV, SLEV, and WEEV. 


Human Cases

West Nile Virus: 1        St. Louis Encephalitis Virus: 3         Western Equine Encephalitis Virus: 0

There were 2 new human WNV case reported last week. There have been 3 WNV and SLEV confirmed, 1 probable WNV and SLEV case, 1 WNV confirmed, and 6 probable human WNV cases reported to the District so far in 2023.

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 4:00 PM (excluding holidays)