West Nile Virus discovered in Visalia mosquito sampling

Mosquitoes in Visalia tested positive for West Nile Virus, the Tulare County Health and Human Services Agency announced Thursday.

Mir Bear-Johnson, the Scientific Program Manager at Delta Vector Control District, said the positive samples were from southwest Visalia.

Delta Vector Control District sets approximately 270 traps every week, Bear-Johnson said.

“We detect West Nile Virus every year in mosquitoes, and we unfortunately within Tulare County do usually also get at least one human case, if not more,” Bear-Johnson said.

Although the virus is detected every year, Bear-Johnson recommends people take precautions because it can lead to serious illness.  

Bear-Johnson recommends using an EPA registered mosquito repellent and to take caution especially during dawn and dusk hours, when mosquitoes are most active.

Wearing long sleeves is recommended. The advised repellent should contain DEET, picaridin, oil of lemon eucalyptus or IR3535.

The virus is first detected around the same time every year, Bear-Johnson said. This year is in week 20. Last year was week 23. The earliest ever detected was in week 17.

West Nile Virus is an illness caused by the bite of an infected female mosquito. Mosquitoes are infected by taking the blood meal from an infected bird.

Symptoms can include fever, headache, body aches, skin rash and swollen lymph nodes. More severe symptoms include disorientation, coma, tremors, convulsions and paralysis.

The Health and Human Services agency urges people to report dead birds and incidences of high mosquito presence, and to drain all standing water from outdoor plant trays and other items that can collect water.

Bear-Johnson warned against standing water that has been still for five days or more, because that gives the possibility of breeding mosquitoes.

Anyone can report mosquito presence by calling Delta Vector Control District at 1-877-732-8606.

Daniel Gligich is a reporter for The San Joaquin Valley Sun, focusing on Fresno State Athletics and the southern San Joaquin Valley. Email him at