With the addition of four West Nile virus (WNV) fatalities during the past week, California has now seen a record high in deaths caused by the mosquito borne virus. Previous highs were in 2014 (31) and 2004 (29).

Public domain image/National Atlas of the United States
Public domain image/National Atlas of the United States

The WNV-related fatalities have been reported in to California Department of Public Health (CDPH) from Butte (1), Kern (1), Los Angeles (11), Nevada (1), Orange (3), Riverside (6), San Bernardino (2), San Diego (5), and Ventura (2).

The past week saw 43 new WNV cases in California, putting the year-to-date total to 512, which is less than the total at this time last year (694), but higher than the 5-year-average of 325.

Nationally, the Centers for Disease Control and Prevention (CDC) reports 1,650 WNV cases and 89 dearths as of Nov. 3.

Related: Chikungunya, West Nile virus and mosquito control in the US: A chat with Clarke’s Dr. Rajeev Vaidyanathan

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.

According to the 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.

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.

Robert Herriman is a microbiologist and the Editor-in-Chief of Outbreak News Today and the Executive Editor of The Global Dispatch

Follow @bactiman63