West Nile virus continues to be detected in mosquitos across Los Angeles County, recently showing up in Signal Hill, the Greater Los Angeles County Vector Control District reported today.

West Nile has already been detected this year in Long Beach and Bellflower. Today, the district said signs of the virus have been found in four additional mosquito samples from traps in Carson, Northridge, Reseda and Signal Hill.

Residents are urged to use EPA-registered repellents when spending time outdoors to prevent mosquito bites and West-Nile-related illness.

Not all repellents are effective against mosquitoes but the Centers for Disease Control and Prevention recommends repellents with the following active ingredients: DEET, Picaridin, IR3535 and Oil of Lemon Eucalyptus.

West Nile virus is endemic in Los Angeles County, and the summer heat can increase virus activity and mosquito populations, according to a district statement.

So far this year, 10 human cases of West Nile have been reported in California, two of which were identified by the Los Angeles County Department of Public Health.

The District works year-round to actively search for and manage water-holding areas such as gutters, ditches, storm drain channels, basins, and non-functional pools and ponds, but there are many more mosquito breeding sites on private property that require the public’s attention, according to the statement.

West Nile virus is a leading cause of severe infections of the nervous system among adults older than age 50 in Los Angeles County. It is transmitted to people and animals through the bite of an infected mosquito. One in five persons infected with the virus will exhibit symptoms, which can include fever, headache, body aches, nausea, or a skin rash.

These symptoms can last for several days to months. One in 150 people infected with the virus will require hospitalization. Severe symptoms include high fever, muscle weakness, neck stiffness, coma, paralysis, and possibly death.