Two samples of mosquitoes taken recently from Eagle Rock have tested positive for West Nile Virus, which is likely to be present in mosquitoes across the neighborhood and beyond.
The latest sample to test positive for the potentially fatal virus was collected Sept. 7 from Lunsford Drive, a dead-end street that runs adjacent to the near the 134 freeway.
An earlier sample was collected from a trap on Aug. 28 from the 1600 block of Campus Road, on the outskirts of —and was the first sample in Eagle Rock this year to test positive for West Nile virus, according to Truc Dever, community affairs director at the Greater Los Angeles County Vector Control District, a California government community health organization that monitors mosquito activity in 34 cities and the unincorporated areas of LA County.
The Campus Road sample contained 31 mosquitoes, which constituted what vector control experts call a cluster or a pool capable of holding up to 50 specimens. The fact that this sample tested positive for West Nile virus means that “perhaps one or all 31 of the mosquitoes” were infected, Truc said.
“Even though a street across Campus Road didn’t have a cluster that tested positive, it doesn’t mean mosquitoes with West Nile virus aren’t there,” Truc explained. “We want people in Eagle Rock and Los Angeles to know that West Nile virus is everywhere—and we want them to take precautions.”
Oxy Notifies Students, Staff
"We have reminded students, faculty, and staff that West Nile is present in Los Angeles and that virus-carrying mosquitoes were recently found near campus," Occidental College Director of Communications Jim Tranquada told Eagle Rock Patch.
"Since there is no vaccine, we are advising the same common-sense measures recommended by the county—try to cover up between dawn and dusk if you're spending time outside, wear repellent, check your screens to make sure they are in good condition, and so on," Tranquada said. He added, however, that he has yet to see any warning signs posted by the county's Vector Control district around campus.
Eighteen People Affected in LA County
As many as 18 people in Los Angeles County are reported to have tested positive for the West Nile virus so far this year, Truc said. The sample collected from Campus Road showed the first positive test this year for the virus in Eagle Rock.
Truc said she would have to check her records to see if samples from Eagle Rock have tested positive for West Nile virus in past years. She was “pretty sure,” however, that Eagle Rock had “West Nile activity in the past.”
Glendale, Burbank and Silver Lake are “generally the areas that show up for positive West Nile virus activity every year,” Truc said.
Heat and Humidity are Factors
Much of the United States is experiencing a high level of West Nile virus activity, Truc said. In fact, more samples of mosquitoes have tested positive for the virus so far this year than in any other year since the virus was first detected in the nation at the Bronx Zoo in New York City in 1999, she added.
Nearly triple-digit temperatures across much of the Los Angeles area, coupled with relatively high humidity, have contributed to increased virus activity.
“The heat plays a major role because it allows mosquitoes to go through their life cycle faster—from eggs to flying adults in about five days,” Truc explained, adding that mosquitoes normally mature in a week or longer.
Two Types of Mosquito Traps
There are two kinds of traps that vector control technicians set up for mosquitoes to monitor West Nile Virus activity, Truc explained. The first is a trap packed with dry ice that emits carbon dioxide. Mosquitoes searching for a blood meal are attracted to the gas, which replicates the breathing of animals. A battery-powered fan sucks in inquisitive mosquitoes into a netting where they remain trapped (or dead) until a technician takes the sample for testing in a laboratory around once a week.
The second type of trap that vector control technicians set up is designed exclusively to catch female Anopheles mosquitoes ready to lay eggs. This trap replicates a standing water source. “We put out dirty, stinking water in a tiny bucket in a cage, and the female [mosquito] gets sucked into it,” said Truc.
The idea behind setting up two different traps is to distinguish between Anopheles mosquitoes, which bite humans, and male mosquitoes that do not, although they may carry the West Nile virus.
The traps, usually well hidden from public view, are placed in public parks, business areas or even the backyards of homes whose residents give vector control agencies permission to set up the traps.
Vector control technicians usually post laminated warning signs within a half-mile radius of spots from where they collect samples that test positive, Truc said. It takes about a week for the laboratory reports to come in from the date of a sample’s collection, and then anywhere from a day to a week for technicians to post warning signs..
Truc said she did not know if a sign had been posted yet on or near Campus Road. A sign on or near Lunsford Drive is likely to be posted “very soon,” she added.
Precautions for the Public
The West Nile virus originates in birds and is transmitted through mosquitoes to humans as well as other animals, including dogs and cats.
Mosquitoes are of course notoriously active from dusk to dawn—“the time when you’re likely to be out on your porch” during summer, Truc noted, offering this bit of handy advice: If you can’t stand wearing full-sleeve shirts and pants because of the heat, make sure to spray exposed parts of your body with a repellent that contains DEET or a comparable active ingredient in insect repellents.