In June 2018, the Los Angeles County Department of 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.