A 78-year-old La Mesa man, who died on Oct 10, was confirmed as West Nile virus (WNV), making him the first death from WNV in San Diego County since 2007.

The man was admitted to a local hospital on October 6 after experiencing symptoms of encephalitis, an inflammation of the brain that can be caused by viral or bacterial infection. He died on October 10. Testing by the California Department of Public Health (CDPH) Viral and Rickettsial Disease Laboratory confirmed today that he had WNV.

West Nile virus
Culex quinquefasciatus mosquito/CDC

He was the seventh confirmed case this year. Three more individuals in San Diego with suspected WNV infections are currently under investigation. One person was a recent blood donor with no symptoms, and the other two have recovered from mild illnesses.

California, due in part to the drought conditions in the state, has reported 608 WNV cases as of Tuesday, making it by far the state with the highest WNV burden this year. California has also seen 20 WNV deaths, not including the La Mesa man.

Last month, Dr. Ron Chapman, director of the California Department of Public Health (CDPH) and state health officer said, “The proportion of mosquitoes infected with West Nile virus is at the highest level ever detected in California.”

As of October 21, a total of 47 states and the District of Columbia have reported West Nile virus infections in people, birds, or mosquitoes. Overall, 1,585 cases of West Nile virus disease in people have been reported to CDC.

Only two human cases of WNV were reported in San Diego between 2009 and 2013, with both of those cases occurring in 2012. The highest number of cases occurred in 2008 when 36 were reported in San Diego.

West Nile virus is a mosquito-borne disease that can cause encephalitis, a brain inflammation. West Nile virus was first detected in North America in 1999 in New York. Prior to that it had only been found in Africa, Eastern Europe, and West Asia.

Related: San Diego: Palomar College student contracts meningococcal disease, no link to SDSU student

According to the Centers for Disease Control and Prevention (CDC), approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms at all.

Up to 20 percent of the people who become infected have symptoms such as fever, headache, and body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back.Symptoms can last for as short as a few days, though even healthy people have become sick for several weeks.

Related: San Diego officials issue plague warning after two more squirrels test positive

About one in 150 people infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness,vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent.

There is no specific treatment for WNV infection. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page