LOS ANGELES — Los Angeles County residents were being warned this week to take precautions against West Nile virus after health officials reported 100 cases this year, the highest number this early in the mosquito season in nearly a decade.
Five deaths have been reported, and almost all of the people diagnosed with the virus have suffered severe illness affecting the brain or spinal cord and required hospital care, according to the county Department of Public Health. Cases have been reported throughout the county.
The last time the county recorded at least 100 cases was in 2017, when 268 cases were reported over the entire mosquito season, health officials said.
“West Nile virus can cause serious illness, and the number of severe cases and deaths we are seeing this year is concerning,” county Health Officer Dr. Muntu Davis said. “We are still within the peak period for West Nile virus transmission, so it is important that everyone take steps now to protect themselves and their families.”
Davis urged residents to use insect repellent, eliminate standing water where mosquitoes can breed and ensure windows and doors have tight-fitting screens without holes or tears.
West Nile virus is endemic to the region and is the most common mosquito-borne disease affecting Los Angeles County residents, according to the health department. Peak mosquito season in the county runs from June through November.
“West Nile virus activity is higher than we typically see, and our teams are actively responding with enhanced surveillance, targeted mosquito control treatments, disease investigations, and increased community outreach and education,” San Gabriel Valley Mosquito and Vector Control District Manager Jason Farned said.
Health officials advised residents to use EPA-registered mosquito repellents containing DEET, picaridin, IR3535, 2-undecanone or oil of lemon eucalyptus. Residents were also urged to properly maintain swimming pools and spas.
West Nile virus is transmitted through bites from mosquitoes that have fed on infected birds. Most people infected with the virus have no symptoms, while about one in five develop a fever and symptoms that can include headaches, body aches, joint pain, vomiting, diarrhea and rash.
About one in 150 infected people develops severe symptoms, which can include high fever, a stiff neck, confusion, muscle weakness or paralysis, according to health officials. People over age 50 and those with health problems face a greater risk of serious illness.
There is no vaccine to prevent West Nile virus infection and no specific treatment for the disease, according to the health department.
As the county reported the number, officials were already mobilizing renewed efforts to eradicate bugs that could carry infection. Mosquito control treatments will be conducted Wednesday and Thursday in a portion of La Puente in an effort to reduce mosquito populations and the risk of mosquito-borne disease amid elevated West Nile virus activity across Los Angeles County, officials said.
The San Gabriel Valley Mosquito and Vector Control District announced it will conduct the treatments by truck between midnight and 5 a.m. both days in the area between Azusa Way and Chatterton Avenue, north of East Valley Boulevard.