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News & Information

Protect Yourself from West Nile Virus

Release Date: July 15, 2013
West Nile virus (WNV) is a viral infection that is spread by the bite of an infected mosquito. This virus most commonly occurs during the summer and early fall months.

Image of Flying Mosquito
Protect Yourself from West Nile Virus

West Nile virus (WNV) is a viral infection that is spread by the bite of an infected mosquito. Mosquitoes become infected with the West Nile virus by feeding on infected birds, then, spread the virus by biting humans and other animals, such as horses. This virus most commonly occurs during the summer and early fall months.

The virus was first identified in North America in 1999 and has since spread across the United States and Canada. In Sussex County, the Office of Mosquito Control has been hard at work addressing the issues of West Nile virus and other mosquito borne illnesses. The office uses an Integrated Pest Management approach to controlling mosquitoes, which includes surveillance, source reduction, fish program, and use of larvicides/adulticides. It starts with the philosophy that a comprehensive prevention and control plan is the most cost-effective and efficient means of controlling mosquito populations.

The Integrated Pest Management approach includes the following components:

Surveillance is conducted by the Office of Mosquito Control throughout the seasons.

  • The staff set various traps throughout the County to collect mosquitoes. The trapped pests are prepared and sent to the New Jersey State laboratory on a weekly basis for analysis.
  • Samples from designated pools are collected in suspected breeding sites and are also sent to the New Jersey State laboratory for testing. It is fairly common for these pools to test positive for West Nile Virus. In 2011, there were 25 pools that tested positive for West Nile and 41 in 2012. However, it is not as common for humans to test positive for West Nile virus and according to the U.S. Geological Survey, there has only been one positively confirmed case reported in the County since 2003.

Source reduction, or the elimination of larval habitat, is the most effective method of preventing mosquito populations.

  • This practice ranges from removing tires and other artificial containers from the landscape to using water management practices to leave habitats inhospitable to mosquitoes. In cases where this is not feasible, controlling mosquitoes in the aquatic habitat is the preferred approach. The mosquito larvae are concentrated and limited to their aquatic habitat; they cannot escape control efforts as adult mosquitoes can.

The Fish Program is another part of this management approach.

  • It involves the use of specific types of fish, often Gambusia and native fat head minnows that are natural predators of mosquitoes. Waterways are stocked with the fish in mosquito breeding sites to provide 24 hour larval control. All sites stocked with fish for mosquito control must be approved by NJDEP's Office of Mosquito Control Coordination.

Products, that work to destroy both mosquito larvae (larvicides) and adult (adulticides) mosquitoes, are sprayed throughout identified areas in the County through various methods, including manual spraying, aerial spraying and the use of a truck-mounted sprayer.

  • Ground larvicide application will be applied only to water that indicates mosquito larvae are present. This application is made to the standing water by a hand carried spray tank; (oil liquid) or a hand carried horn spreader, (granular formulation).
  • Due to size of some of the larval mosquito habitats in Sussex County, our operation sometimes involves applications of larvicide by aircraft or aerial spraying.
  • As a final line of defense, a treatment for adult mosquitoes may be applied by truck-mounted sprayer if a significant mosquito population exists.

The virus can affect anyone bitten by an infected mosquito. The risk of infection is highest for people who work outside or participate in outdoor activities because of greater exposure to mosquitoes. People over the age of 50 and those with weak immune systems are also at greater risk of developing severe illness. However, West Nile Virus is not spread from person to person.

Many people infected with West Nile virus do not become ill and may not develop symptoms. About 20% of infected people will develop West Nile virus. When symptoms do occur, they may be mild or severe and begin about 2 to 14 days after being bitten by an infected mosquito.

  • Mild symptoms include flu-like illness with fever, headache, body aches, nausea, joint pains, vomiting, diarrhea, or rash.
  • Severe symptoms include high fever, neck stiffness and swelling of the brain (encephalitis) which can lead to coma, tremors, seizures, and paralysis. Less than 1% of infected people will develop severe symptoms.

There is no specific treatment for West Nile virus and no vaccine for humans. Most people with West Nile fever will recover in approximately seven days. Antibiotics are not effective against viral illnesses and anti-viral drugs have not shown to be effective for treating West Nile virus. Most treatment focuses on supportive therapy to lower fever and ease pressure on the brain and spinal cord. In severe cases, hospitalization may be needed.

The best way you can help to prevent West Nile virus is by avoiding mosquito bites.

  • Use insect repellents when you go outdoors.
  • Wear long sleeves and pants from dusk through dawn when many mosquitoes are most active.
  • Install or repair screens on windows and doors.
  • Help reduce the number of mosquitoes around your home by emptying standing water from containers such as flowerpots, gutters, buckets, pool covers, pet water dishes, discarded tires, and birdbaths.

For additional information about the Sussex County Office of Mosquito Control Program, please visit the website at For more information on West Nile Virus and Mosquito Control, please visit the New Jersey Department of Environmental Protection, at or Centers for Disease Control and Prevention (CDC) website, at