First Human Case of West Nile Virus Reported in LA County
In June 2018, the Los Angeles County Department of Public Health (Public Health) identified the first case of human West Nile virus (WNV) infection in Los Angeles County for the 2018 season (excluding Long Beach and Pasadena as cases identified in those cities are reported by their local health departments). A resident of the San Gabriel Valley region of Los Angeles County was hospitalized in mid-May and WNV was confirmed as the cause by the California Department of Public Health.
“West Nile virus is spread by the bite of an infected mosquito. It can affect the nervous system and result in meningitis, encephalitis, paralysis and even death. While all county residents are at risk for West Nile virus, people over 50 years of age and those with chronic medical problems are at higher risk of severe disease,” said Jeffrey Gunzenhauser, MD, MPH, Interim Health Officer for Los Angeles County. “Residents should take protective action by using Environmental Protection Agency (EPA)-registered mosquito repellent when outdoors and check for, clear, clean or cast-off items that collect standing water in their homes or yards where mosquitoes can breed.”
The number of people infected with WNV each year in LA County is estimated to be more than 10,000, because most infected persons do not experience any illness or perhaps only mild illness. These cases are neither reported nor even recognized as WNV. Moreover, Public Health continues to report elevated numbers of WNV cases in LA County over the previous 5 years, at an average of 221 cases per year. Over three-quarters of reported cases have had severe disease and approximately 7% of patients with severe WNV have died from complications. Last year’s WNV season was the longest season on record extending until mid-December.
Public Health collaborates with local vector control agencies to target areas for mosquito control activities as well as educate people about how to protect themselves. There is no vaccine for WNV and no treatment to cure the illness once an individual becomes sick. Reduction of mosquito breeding sources and protection from mosquito bites are key to prevention.
“The announcement of the first human case of West Nile virus in San Gabriel Valley should serve as a reminder to residents to take steps to prevent mosquito bites and eliminate mosquito breeding on their property. Taking just a few minutes to remove any standing water from your yard, apply recommended mosquito repellents, and ensure your window and door screens are free of holes can help protect you and your community from this dangerous disease.” said Jared Dever, District Manager of the San Gabriel Valley Mosquito and Vector Control District.
Stagnant swimming pools or “green pools” should be reported to the Public Health Environmental Health Bureau at (626) 430-5200, or to a local vector control agency. Dead birds may be reported by visiting this website or by calling (877) 968-2473.
About West Nile Virus: WNV is spread to humans through the bite of an infected mosquito; mosquitoes become infected by biting a bird that carries the virus. Most mosquitoes do not carry the virus, therefore most people bitten by a mosquito are not exposed to WNV. The virus is not spread through person-to-person contact or directly from birds to humans.
Recovery from WNV can take months or years. One study showed that 12 months after infection, about half of those with this disease continued to have cognitive and physical impairment such as memory loss, difficulty walking and fatigue. In addition to those who develop more serious illness, people infected with West Nile virus may develop mild symptoms that include fever, headache, nausea, body aches, and a mild skin rash.
Decrease risk of infection:
- Avoid mosquito-infested areas at dawn and dusk.
- Consider wearing long-sleeved shirts and long pants when you are outdoors, particularly at these times and when in areas where more mosquitoes are present.
- Use repellents containing DEET, picaridin, or oil of lemon eucalyptus. These are effective defenses against mosquitoes when used as labeled.
- Check your window screens for holes.
- Dump stagnant water. Do not allow water to collect and stagnate in old tires, flowerpots, swimming pools, birdbaths, pet bowls, or other containers. These are prime breeding grounds for mosquitoes.
- Clean and chlorinate swimming pools; drain water from pool covers.
- Stock garden ponds with goldfish or other mosquito- eating fish. These eat mosquito eggs and larvae.
- Empty and wash birdbaths and wading pools weekly.
- Cover rain barrels and empty weekly
More information and resources:
- West Nile virus in LA County
- West Nile virus in California
- It's Not Just A Bite, a mosquito-borne disease public health campaign
Where to call with questions about mosquitoes:
- Greater Los Angeles County Vector Control District: (562) 944-9656
- Los Angeles County West Vector Control District: (310) 915-7370
The Department of Public Health is committed to protecting and improving the health of over 10 million residents of Los Angeles County. Through a variety of programs, community partnerships and services, Public Health oversees environmental health, disease control, and community and family health. Nationally accredited by the Public Health Accreditation Board, the Los Angeles County Department of Public Health comprises nearly 4,100 employees and has an annual budget of $1 billion. Please visit the Los Angeles County Public Health website for more information and follow LA County Public Health on social media at Twitter, Facebook and YouTube.