/District Urges Public to Remain Vigilant Against West Nile Virus as Fall Begins

District Urges Public to Remain Vigilant

Against West Nile Virus As Fall Begins Prevention remains important as temperatures cool, but mosquitoes remain active

September 20, 2005

LAS VEGAS – Sept. 20, 2005 – As fall begins, the health district reminds residents and visitors to continue preventive measures to avoid being bitten by mosquitoes that carry West Nile virus. The mosquito season in Clark County will continue through the end of October.

“As temperatures cool and people spend more time outdoors, particularly around dawn and dusk, there is greater potential for mosquito bites,” said Dr. Donald Kwalick, chief health officer. “Mosquitoes that carry West Nile virus are still active throughout Clark County and in neighboring counties and states, so protective actions to avoid bites remain necessary.”

Four Clark County residents have been infected with West Nile virus this year. Two suffered a mild form of illness called West Nile Fever, while two suffered the more severe West Nile Encephalitis. All have either recovered or are in the process of recovering from their illness. There have been no West Nile virus related deaths in Clark County residents.

The Nevada Department of Agriculture has noticed an increase in the number of horses being infected with West Nile virus in the Pahrump area. The disease can be severe in horses, and the level of activity raises concerns that people are also being bitten. Symptoms of West Nile virus infection in horses include listlessness, stumbling and lack of coordination, weakness of limbs, nervous disorders, partial paralysis and death.

“We have fewer cases of West Nile Virus in horses this year with one exception, Nye County,” said Ed Foster, spokesman for the Nevada Department of Agriculture. “It’s imperative that Nye County horse owners vaccinate their animals. West Nile Virus is not going to go away,” Foster added.

Currently there are two licensed vaccines for horses. Because adequate protection requires nearly two months, the Nevada Department of Agriculture is encouraging Nevada horse owners to have their horses vaccinated for West Nile virus immediately.

West Nile virus is spread to people through the bite of infected mosquitoes, which acquire the virus by feeding on infected birds. The illness is not spread person to person or through direct contact with horses. The health district stresses the need for individual protective actions to avoid mosquito bites:

  • Apply an insect repellent containing DEET (N, N-diethyl-meta-toluamide) according to manufacturer’s directions. Repellents containing picaridin and oil of lemon eucalyptus also have some efficacy. However, DEET is the best-studied and most-effective repellent available.
  • Wear pants and long-sleeved shirts, when outdoors.
  • Avoid spending time outside when mosquitoes are most active, notably at dusk (the first two hours after sunset) and dawn.
  • Eliminate areas of standing water, including bird baths, un-maintained swimming pools and sprinkler runoff, which support mosquito breeding.

Future updates on human West Nile virus cases will be posted to the health district website at www.southernnevadahealthdistrict.org.

For additional information on West Nile virus, including updated maps of West Nile virus positive mosquitoes, birds and horses, visit the Southern Nevada Health District website at www.southernnevadahealthdistrict.org. The public may also call the West Nile virus hotline at (702) 759-1220 with questions, concerns or to report standing water and large numbers of mosquitoes.

Visit the Media Contacts webpage for media related inquiries.


The Southern Nevada Health District serves as the local public health authority for Clark County, Boulder City, Henderson, Las Vegas, Mesquite and North Las Vegas. The agency safeguards the public health of the community’s residents and visitors through innovative programs, regulations, and initiatives focused on protecting and promoting their health and well-being. More information about the Health District, its programs, services, and the regulatory oversight it provides is available at www.SNHD.info.