Virus causing encephalitis found in Stanislaus County mosquito. Are humans at risk?
The virus that causes St. Louis encephalitis was detected in a mosquito sample in Stanislaus County, health officials said Wednesday.
The St. Louis virus is a relative of the West Nile virus, which gets attention in the Central Valley every year for causing a potentially deadly neurological illness in some residents.
In a small number of cases, St. Louis encephalitis may include symptoms such as headache, confusion, dizziness, seizures, paralysis or even death. But most people who become infected will not feel sick.
County health officials advised the public to avoid mosquito bites, which can transmit West Nile or St. Louis illness, and also take steps to prevent mosquito breeding in the community.
“There is no specific treatment for St. Louis or West Nile virus, so it is very important that people protect themselves and their families from mosquito bites,” Dr. Julie Vaishampayan, county public health officer, said in a news release. “We ask everyone to use mosquito repellents to protect themselves and their loved ones from mosquito-borne viruses, especially when they are outdoors.”
St. Louis encephalitis has turned up in mosquito samples in six California counties this year including Stanislaus, Madera, Fresno, Tulare, Riverside and Imperial. No cases of illness have been reported.
Stanislaus County had one of the four known cases of St. Louis illness in California last year.
Evidence of West Nile virus has been widespread with more than 130 mosquito samples and two dead birds testing positive in Stanislaus County in 2021. According to a state website, three cases of West Nile have been confirmed in Stanislaus, two in Merced and two in San Joaquin, while only 35 cases have been tallied statewide.
A county resident in his 70s became sick with St. Louis encephalitis in September 2017 with symptoms of fatigue, fever and abdominal pain. He was not hospitalized. Samples of his blood were tested and more tests were run by the California Department of Public Health and Centers for Disease Control and Prevention to confirm the virus.
California had three cases of St. Louis encephalitis in 2016.
To avoid a bout with West Nile or St. Louis illness, people can drain standing water around their homes, wear insect repellent and avoid being outdoors near dawn or dusk when mosquitoes are active.
Mosquito problems north of the Tuolumne River can be reported by calling Eastside Mosquito Abatement District, at 209-522-4098. Other county residents may call Turlock Mosquito Abatement District at 209-634-1234. Additional information is available at www.eastsidemosquito.com and www.turlockmosquito.org.
This story was originally published September 15, 2021 at 2:56 PM.
