Mosquito Season Isn't Over Yet

In normal years, mosquitoes have come and gone by November. Being cold-blooded insects, the absence of warm weather causes them to lie dormant until spring. But California's drought has aggravated the numbers of mosquitoes (and mosquito bites) this year, with a reported 752 cases of West Nile virus in 31 counties, more than double the number of cases last year. Orange County, in particular, has the greatest concentration of West Nile infections in the state: 262 cases so far this year, according to recent data.

What's causing the staggering rise in infections? For one, less water means the water sources that do exist are more likely to stagnate. Stagnant water is prime breeding ground for mosquitoes.

One of the key factors in the current elevated state of West Nile virus has been the high rate of foreclosures throughout the region, which has left many abandoned houses with stagnant swimming pools and birdbaths.

Drought conditions also mean a likelier chance of infection by birds, where West Nile virus originates. When mosquitoes feed on infected birds, they spread the virus to the birds and humans they bite next. A shortage of water can accelerate this cycle as birds and mosquitoes seek out the same water sources, thus coming in closer contact with one another and increasing the chances of mass infection.

Statewide, there are now 2,430 cases of dead birds that have tested positive for West Nile virus. This week alone, 19 new human cases have been confirmed, at a time when mosquitoes are typically winding down for the season.

The California Department of Public Health recommends that people practice the "Three Ds" to protect themselves from possible exposure:

• DEET - Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.
• Dawn and Dusk - Mosquitoes bite in the early morning and evening so it is important to wear protective clothing and repellent if outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
• Drain - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, and buckets. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.