By Gavin J. Quinton
and Mia Alva
Burbank leads the Los Angeles County area in the number of positive cases of West Nile Virus found in mosquitos, with 12 total documented samples.
In May, Burbank became the first city in Los Angeles County to have a confirmed positive West Nile mosquito sample in 2023. The positive mosquito sample was collected from one of two mosquito traps in the city, confirming the presence of the virus in mosquito populations within the community.
Since then, the virus has been detected in most cities across the county, some with a first detection as late as last month. Studio City trails Burbank with 11 positive samples, and there have been 288 total detections this year in the region, according to the Greater Los Angeles County Vector Control District most recent data.
As of Friday, a total of 64 human cases have been documented in Los Angeles County so far this year, and while Burbank was listed as a city with human cases, the number is unknown. The number of cases for the 2023 season is higher than the previous five-year average, according to the Los Angeles Department of Public Health.
There have been two deaths in the county so far, and experts say human infections will likely continue to occur through the rest of the fall.
The current 2023 figure of 288 mosquito West Nile detections is lower than last year’s total of 372 — with only three in Burbank — but far exceeds the number of samples in 2021, which was 65. Experts at GLACVCD told the Leader that the presence of the disease is cyclical.
“West Nile virus is really active here in California,” Steve Vetrone, director of scientific-technical services at GLACVCD, told the Leader. “We have mosquitoes test positive for West Nile virus every single year. It all depends on what’s happening with the immune status of birds in different areas.”
West Nile Virus is monitored closely throughout California. Humans get West Nile from the bite of an infected mosquito. Usually, the virus causes mild, flu-like symptoms, but it can affect the brain and spinal cord causing meningitis, encephalitis and paralysis. There is no vaccine available to prevent West Nile virus. The disease is more prominent elsewhere in the world but was first detected in California in 2003.
Testing and vector control are managed by the GLACVCD, a public health agency that monitors the spread of diseases in Los Angeles. Examples of mosquito-borne diseases include West Nile Virus, Zika, Chikungunya, Malaria and Dengue, to name a few.
“West Nile Virus is spread among the wild bird populations and transmitted to humans through the bite of an infected mosquito,” said Vetrone. “This virus is endemic in our region which means we will always see virus activity in Los Angeles County.”
The Los Angeles County Department of Public Health recently confirmed the first two deaths due to West Nile virus for the 2023 season in the county in September. The first patient death was a resident of the San Fernando Valley area, who was hospitalized and died from a West Nile virus-associated neuro-invasive disease.
“I send my deepest condolences to the family and friends of this resident who sadly passed away from West Nile virus,” said Dr. Muntu Davis, Los Angeles County Health Officer. “Their death reminds us how important it is to protect ourselves from mosquitoes and prevent them from breeding near our homes. Using mosquito repellent and keeping mosquitoes out of our homes can help prevent West Nile virus. Let’s all work together to keep our homes and neighborhoods mosquito-free for everyone’s safety.”
People over 50 years of age and those with chronic medical conditions, such as cancer and diabetes are most vulnerable to severe symptoms caused by WNV.
The native Culex mosquito is capable of transmitting West Nile virus and it is most active during dusk and dawn. The newly invasive Aedes mosquito — also called the “ankle biter” cannot transmit WNV, but its increasing presence in the region has experts concerned about the potential increase in other vector-borne illnesses like Dengue, which can be transmitted from human to human. Aedes mosquitoes are active for longer periods of the year.
“Because of these new mosquitoes, an invasive species, Mosquito season has been extended dramatically,” said Vetrone. “They are still very present now at the beginning of November so they will definitely have an impact on how we enjoy our outdoor space.”
The best line of defense, Vetrone said, is reducing still water sources, removing empty water containers and wearing insect repellents.
There are different kinds of mosquito repellents available, but they do not all work equally well. The Centers for Disease Control and Prevention recommends products with the active ingredients DEET, Picaridin, IR3535, or oil of lemon eucalyptus as being safe and effective when used according to the labels.
“We encourage residents to protect themselves by applying insect repellent with one of the recommended active ingredients at 15% or higher when outdoors, particularly at dusk and dawn,” said Vetrone. “Residents can also wear loose-fitting long sleeves and pants to help deter bites.”
Residents can take an active role in reducing the threat of WNV in their neighborhoods by taking these additional steps:
• Eliminate standing water in clogged rain gutters, rain barrels, discarded tires, buckets, watering troughs or anything that holds water for over a week.
• Ensure that swimming pools, spas, and ponds are properly maintained.
• Change the water in pet dishes, bird baths and other small containers weekly.
• Request mosquitofish from your local vector control district for placement in ornamental ponds.
• Report neglected swimming pools in your neighborhood to your vector control district.
For an extensive list of common indoor and outdoor sources and recommended solutions, visit bit.ly/diy-mosquito-solutions. For more information, residents can contact the Greater Los Angeles County Vector Control District at 562-944-9656, online at GLAmosquito.org, or on social media: Facebook, Twitter, Instagram.
First published in the November 4 print issue of the Burbank Leader.