The first human case of West Nile virus (WNV) infection has been identified in Los Angeles County for the 2017 season. An elderly resident of the San Gabriel Valley region of Los Angeles County was hospitalized 3 months ago and West Nile virus was recently confirmed as the cause. The patient has fully recovered.

“West Nile is a serious illness spread by mosquitoes in Los Angeles County. Take precautions against mosquito bites such as using a repellent containing DEET when outdoors, especially around dawn or dusk,” said Jeffrey Gunzenhauser, MD, MPH, Interim Health Officer for Los Angeles County.

WNV’s Complications

WNV is might cause severe infections of the nervous system among adults older than age 50 such as meningitis, encephalitis, or even paralysis.

In 2016, during the mosquito season in the summer and fall, 153 cases and 5 deaths from WNV were reported to Public Health. Of the 153 West Nile cases, 48 presented with meningitis, 53 with encephalitis, and 5 with paralysis. People most at risk of WNV include elderly people who are often outside walking where they are bitten by a mosquito and people who are immunocompromised because of medications or illness.

Public Health collaborates with local vector control agencies to fulfill mosquito control and educate people about how to protect themselves.

WNV mode of infection

WNV is transmitted to humans through the bite of an infected mosquito, which became infected by sucking the blood of a bird that carries the virus. However, most mosquitoes do not carry the virus and the virus is not spread through person to person contact or directly from birds to humans.

WNV infections are commonly represented as severe infections, and recovery from the disease might take months or years. One study reported that 12 months after infection, about half of infected patients continued to have cognitive and physical deterioration such as amnesia and fatigue.

However, people infected with West Nile virus could present mild flu like symptoms that include fever, headache, nausea, body aches, and a mild skin rash.