Mosquitoes are tiny pests but have the potential to create a menace to humans if carrying the West Nile virus.
The virus can cause inflammation of the tissues that cover the brain and spinal cord, Maria Peinado, Imperial County Public Health Department information officer, said in a bulletin.
Many mosquitoes survive the winter in drains that protect them from the elements, said John Feller, county health department vector control technician.
Feller was treating a “green pool” on Smoketree Drive on Tuesday. These are neglected or abandoned pools with stagnant water and vegetative debris that serve as fertile mosquito breeding grounds, he said.
Spraying the pool with a larvaecide, he coated the water so larvae cannot get oxygen and suffocate. Conducting aerial surveillance, the health department has identified 50 homes with such pools, and then dispatches technicians to inspect and treat them if necessary, Feller noted.
The health department began a campaign two years ago, distributing fliers asking residents to report green pools, said Tim Hodgkin, vector control supervisor. People may phone 760-336-8530.
Because a pool is a large breeding source it has the potential to produce millions of mosquitoes. In densely populated areas the insects can create havoc if they are infected, Hodgkin said. Although it does not drain pools, the health department tries to work with homeowners to mitigate the problem in as mutually a convenient manner as possible, he said.
Many of these homes have been foreclosed on and abandoned. For others, owners are on extended stays out of town or just negligent, he noted. Breeding grounds also include bird feeders, old tires or any container left outside collecting rainwater; these problems can be avoided with simple but vigilant care, he said.
Mid-May through July is prime season and it is best to limit time outdoors when mosquitoes are most active, from dusk to two hours later, Hodgkin said. Repellents such as DEET and Picaridin are some of the most effective.
There have been seven recorded cases of West Nile in Imperial County since 2003. Symptoms are similar to the flu and only on rare occasion are fatal, Hodgkin said. But he cautioned anyone who suspects they have been exposed to consult a physician. The elderly and very young can be especially vulnerable, he noted.