Prepare For West Nile Virus Season

Ruzanna Harutyunyan's picture

The Southern Nevada Health District’s annual West Nile surveillance program is gearing up for 2009. Property owners are urged to begin eliminating mosquito breeding sources to decrease the mosquito population. In 2008, Nevada had a total of 16 human cases of West Nile virus.

The health district advises everyone to be vigilant and conscientious about mosquito breeding sources, which can be as little as a cup of water to be effective. In 2008, the health district’s vector control program responded to more than 2,850 green pool complaints, many of these were abandoned homes.

The health district’s environmental health specialists routinely survey and treat known breeding sources for mosquitoes and trap them for identification. In addition, they are tested for West Nile virus, Western equine encephalitis and St. Louis encephalitis. In response to complaints, environmental health specialists use several options such as larvicide or mosquito fish to treat stagnant water sources.

Stagnant water sources are the optimal breeding source for mosquitoes. There are 17 mosquito species in Southern Nevada, however, only a few are known to “feed” on humans and horses and carry disease. The health district recommends the following strategies to eliminate standing water:

Swimming pools


* Maintain water circulation and chemical concentrations
* Remove rain water from pool covers
* Stock “out-of-order” pools with mosquito fish
* Change water weekly in wading pools
* Store wading pools indoors when not in use
* Store wading pools upright

Ornamental pools

* Stock with fish
* Remove leaves and thin out plants
* Keep water levels up and keep water clean
* Screen the inlet of the recirculation pump
* If not in use, break holes in the bottom and refill with sand

Standing water sources

* Repair leaky plumbing under and around the house
* Prevent seepage from garden irrigation
* Divert storm water away from foundations
* Drain the air conditioner outlet
* Clean rain gutters
* Remove and dispose of all unused containers that collect water
* Change water weekly in rooting plant containers
* Usable containers should be stacked upside down

West Nile virus made its first appearance in the United States in the late 1990s in New York and has since spread across the country. The disease first appeared in Nevada in 2003. Last year, the Centers for Disease Control and Prevention reports there were 1,338 confirmed human cases of West Nile in the United States; 43 deaths were reported.

West Nile virus is spread through the bite of infected mosquitoes, which acquire the virus by feeding on infected birds. The illness is not spread person to person or by casual contact.