West Nile Virus reported in Riverside County


The State Health Department has confirmed several human cases of West Nile virus infection this year, bringing the total number of human cases in Riverside County to 11.  As reported earlier this month, nine of these infections are in areas served by the Northwest Mosquito and Vector Control District, which includes Canyon Lake.

The Northwest Mosquito and Vector Control District is on full alert regarding mosquito activity. “From the surveillance data, there are indications that this could be one of the worst years for WNV infections in Riverside County,” say Dr. Major Dhillon, District Manager. Historically, most infections occur during the months of September and October.  Therefore, the District crews have been increasing control measures for immature and adult mosquitoes. In light of increased virus activity and potential public health threats, the District has been spraying to kill adult mosquitoes. The mosquito efforts along the Santa Ana River (cities of Eastvale, Jurupa Valley, Norco, Corona and Riverside) and subsequent areas of the District are being monitored very closely.

West Nile virus is transmitted to humans and animals through the bite of an infected mosquito. Approximately 20 percent of the humans infected experience mild symptoms, such as fever, headache and body aches. Less than one percent of individuals will develop a serious neurologic illness.

The elderly, children or individuals with compromised immune systems are usually at higher risk of experiencing further manifestations of the disease. Anyone with symptoms should contact their health care provider.

The District requests that residents avoid creating standing water sources on their property. In Canyon Lake, anyone knowing of a standing water source, such as an unmaintained swimming pool, is asked to contact Special Enforcement Officer Jean Voshall at City Hall so that proper action can be taken.

Residents are highly encouraged to take the following precautions and protective measures.

To protect oneself from mosquito bites:

  • Use an insect repellant with DEET, picaridin or oil of lemon eucalyptus. Be advised to follow the product label whenever the product is to be applied to children. Lemon eucalyptus oil should not be used on children under 3 years of age.
  • Dawn and dusk are peak biting times for many mosquitoes. Consider rescheduling outdoor activities during that time.
  • Wearing long sleeves, long pants and socks when outdoors can reduce exposure to mosquito bites.

To mosquito-proof your home

  • Drain or dump standing water. Mosquitoes lay their eggs in standing water; therefore, eliminate any standing water on your property. Check rain gutters and drains. Empty unused flowerpots and wading pools. Change water in bird baths and pet bowls at least once a week.
  • Keep mosquitoes outside by having tight fitting screens on all windows and doors.

As of September 3, West Nile virus has been found in 40 counties in California, with 2,073 mosquito samples testing positive for the virus and 83 confirmed human cases in the state.  The Northwest Mosquito and Vector Control District has 19 WNV positive mosquito samples and nine positive human cases.

Contact the District at 951-340-9792 to report mosquito problems, request mosquito fish, report neglected pools or standing water where mosquitoes breed or to report dead birds.  Visit www.northwestmvcd.org to obtain more information and submit service requests. For the latest statewide statistics for WNV activity, visit www.westnile.ca.gov.

To report unmaintained pools or other standing water in Canyon Lake, contact City Hall at 951-244-2955.


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Donna Ritchie