Mosquitoes a concern on Hill: Stagnant water poses good homes for mosquito eggs

Vector control was the topic at last week’s Mountain Emergency Services Committee meeting. With the expectation of above-normal precipitation this winter, Kathleen Henderson, the Riverside County emergency services coordinator for the mountain, thought a discussion of how to deal with mosquitoes and other disease carriers would be helpful for local residents.

Doug Osborn, the supervising environmental health specialist for the county Department of Environmental Health, began with an explanation of the meaning of a “vector” and the dangers some pose to Hill residents.

“A ‘vector’ is any organism, such as a mosquito or rodent, that transmits pathogens or bacteria to humans,” he began. “On the Hill, 90 percent of our threats come from mosquitoes. These small-winged creatures can transmit to humans the following diseases: West Nile virus, yellow fever, chikungunya, dengue, malaria and now Zika. Our local canines are susceptible to heartworm, which mosquitoes also transmit.”

Other dangers, which have been identified on the Hill, include the plague, hantavirus and Lyme disease.

The current and biggest concern is West Nile fever. Osborn stressed, “It does kill people and two different mosquito species transmit it.”

The WNV has been in California for more than a decade. Since 2003, more than 5,500 people have been infected and 221 have died, 45 of them in 2015. While 17 percent of the infections last year were in Riverside County, none of the deaths occurred here.

Although there is no human vaccine for protection from the WNV, there is an equine vaccine, according to Osborn.

Vector Control can be reached at 955-766-9459. It will investigate the problem, identify the vector (mosquito, rodent, other or none) and provide treatment, Osborn stated.

The Zika virus has created a major international situation. Although the public health community has been aware of it for decades, it is now spreading into much larger populated areas.

Although several Californians have contracted the virus, they were infected outside the United States. Osborn emphasized that the virus has not been found in California.

While adults may suffer severe symptoms such as joint pain and fever, a fetus is susceptible to possible microencephlya or even Guillain-Barrésyndrome, an uncommon sickness of the nervous system. GBS causes a person’s immune system to damage nerve cells, which will result in muscle weakness, and sometimes, paralysis.

The mosquito species, which transmits this virus, has known habitat in the San Jacinto Valley, but Osborn stressed that “there have been no locally transmitted cases in Riverside County.”

Another vector is the deer mouse, which can carry the hantavirus. Several years ago, the virus was detected on the northern edges of the San Jacinto Mountains. Similarly, the plague, which is carried by fleas on rodents, has occasionally been identified on the Hill. There are no current cases reported, according to Osborn.

One danger, which Vector Control does not address, is rabies, which can be transmitted by bats.

Before the meeting ended, Henderson introduced Jerry Hagen, who this spring will assume responsibility for the mountain area and all of Riverside County District 3. The county Emergency Management Department has realigned its staff to correspond with the county’s supervisory districts. Henderson will work with District 2 agencies, when the change is implemented.