West Nile Virus cases confirmed in Fresno County

Health department confirms three cases of West Nile Virus, warns the number of infections will increase as mosquito season comes into full force

Fictional Blood samples with infected west-nile virus, with stethoscope, mask and syringe and other stuff.
Darren Fraser
Published July 11, 2024  • 
10:30 am

FRESNO COUNTY – Alongside the rise of mosquito season comes the risk of mosquito-borne illnesses, calling for a word of caution from the Fresno County Department of Public Health as it has confirmed three cases of West Nile Virus thus far.

According to a July 10 press release from the department, the three cases were detected through routine testing of blood donors. The three human cases add to the total of 56 positive mosquito samples recorded this year in the county, which were reported by mosquito abatement districts.

Fresno County health officials say the number of human cases of WNV is expected to increase as mosquito season – June to November – comes into full force.

“We need to stay vigilant as mosquitoes may continue to cause severe illnesses, including WNV infection, which can require hospitalization and intensive care,” Dr. Rais Vohra, Fresno County Interim Health Officer, said in the press release.

Infections of WNV can range from mild to severe. Mild symptoms include fever, headache, body aches, joint pains, nausea, vomiting, diarrhea, rashes, swollen lymph glands and a sore throat. Severe symptoms include neck stiffness, muscle weakness, stupor, disorientation, tremors, convulsions, paralysis, coma and loss of vision.

Symptoms typically manifest three to 14 days after being bitten. These can last from a few days to several weeks. Most individuals who display mild symptoms recover completely, though fatigue and weakness can linger for months. Health officials recommend seeking immediate medical attention if you display signs of a serious infection.

WNV is transmitted when mosquitoes bite birds infected with the virus and then bite humans.

FCDPH says residents should take the following precautions to avoid infection:

  • Apply an EPA registered insect repellent that contains DEET – diethyl-meta-toluamide, picaridin, oil of lemon eucalyptus or IR 3535. The insect repellant should be applied at dawn and dusk when mosquitoes are most active;
  • Doors and windows should have tight-fitting screens to keep out insects;
  • Eliminate standing water and items that contain water from around the home; and
  • Contact your local mosquito abatement district to report poorly maintained swimming pools or water sources that appear green.

More information is available at www.fresnocountymosquito.org. Residents are asked to report dead birds by visiting https://westnile.ca.gov/ or by calling 1-877-WNV-BIRD.

Information can also be found by contacting the Consolidated Mosquito Abatement District (559-896-1085), the Fresno Mosquito and Vector Control District (559-268-6565) or the Fresno Westside Mosquito Abatement District (559-659-2437).

The California Department of Public Health (CDPH) notes that there were 433 symptomatic human cases of WNV in 2023. There were 19 fatalities and 40 asymptomatic infections in blood donors.

Since 2003, when the virus was first detected in the state, there have been more than 8,000 WNV cases and more than 390 WNV-related deaths.

Darren Fraser