LOS ANGELES, CA — West Nile virus showed up in new test results four mosquito traps across Los Angeles, including Northridge, Reseda, Carson and Signal Hill, the Greater Los Angeles County Vector Control District reported Monday.

West Nile virus is endemic in Los Angeles County, and signs of the virus appear to be spreading, authorities warned. In addition to clearing standing water around their homes, residents should use EPA-registered repellents when spending time outdoors because not all repellents are effective against the blood-sucking bugs. The Centers for Disease Control and Prevention recommends repellents with the following active ingredients: DEET, Picaridin, IR3535 and Oil of Lemon Eucalyptus. So far this year West Nile Virus carriers have been found in these Los Angeles County neighborhoods:

Authorities warn that the summer heat can increase virus activity and mosquito populations. As the season heats up, 10 people have confirmed West Nile Virus infections in California, two of which were identified by the Los Angeles County Department of Public Health. Most people who contract the virus, don't exhibit symptoms although it can be deadly to some. Vector control officials need the public's help in curbing the spread of the disease. The District treats 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.