Mosquitoes collected near Torrey Pines Drive and Los Serranos Country Club Drive in Chino Hills June 25 and 28 have tested positive for the West Nile Virus.
It is the first indication this year of a positive testing, said Brian Reisinger of the West Valley Mosquito and Vector Control District.
The mosquitoes could have been caught up to a one-mile radius around the trap location, Mr. Reisinger said.
He advises the community to dump out standing water near their homes, wear repellent outdoors, and call the District if they have mosquitoes, at 635-0307.
The District regularly traps and tests mosquitoes to check for the virus, he said.
Officials warn that in the summer, water that sits for longer than 48 hours such as in planter pots, birdbaths, and pet water bowls, can have enough algae and bacteria to support larvae development.
Ponds and water gardens should be agitated using a sprinkler, they advise
Mr. Reisinger said mosquito fish are available free of charge at the District office, 1295 E. Locust St. in Ontario.
The fish are able to eat large quantities of mosquito larvae in any permanent or semi-permanent water source that doesn’t drain into U.S. waters, he said.
Mosquito fish could be placed in ponds, water gardens, and horse troughs.
People over 60 are at greatest risk of getting sick and are more likely to develop serious symptoms when infected, according to the California West Nile Virus website.
Up to 20 percent of people who become infected will have symptoms that could include body aches, fever, headaches, nausea, and vomiting. Eighty percent of those infected develop no symptoms.