Crook County Health Department shares

plan for protection from West Nile Virus

One of our community’s important health partners, Crook County Health Director Muriel Delavergne-Brown, RN, BS, PHN, has asked that I share with you a plan for your protection from West Nile Virus. With the return of warmer wet weather comes the return of mosquitoes, the vector, or carrier, for this disease.

West Nile Virus was first documented in Oregon in 2004. In Crook County , we had one bird, a Steller’s jay, test positive for the virus that year. In 2007, Oregon documented 27 human cases of West Nile Virus infection and positive WNV tests in 11 sentinel chicken flocks, 52 birds, 32 mosquito pools and 17 horses. It is expected that the risk of human exposure to West Nile Virus in Oregon will increase over the next few years as more mosquitoes become infected and spread the disease.

The Crook County Health Department and the care providers at Pioneer Memorial Hospital want to help you decrease your personal risk of contracting West Nile Virus through mosquito bites, and to help you understand the consequences if you do acquire the virus. We also want to give guidance on ways to limit your exposure to mosquitoes and to help eliminate them from your property.   

SYMPTOMS

The majority, about 80 percent, of people who acquire West Nile Virus infection will not have any noticeable symptoms.

Around 20 percent of people will notice mild to moderate symptoms classified as “West Nile Fever.” These symptoms are similar to ones that may be seen in other illnesses and may include fever, weakness, fatigue, loss of appetite, nausea, vomiting, eye pain, headache, muscle aches, rash and swollen glands.

Recent data indicates that West Nile Fever is more significant than previously thought. Duration of symptoms ranges from five to 60 days, with a mean of 28 days. Long-lasting effects are not uncommon. Studies have found residual conditions, measured one year after the onset of disease, of personality changes (34 percent), persistent fatigue (31 percent), depression (29 percent) and weakness (25 percent) for people diagnosed with West Nile Fever.

Approximately 1 percent of those infected with West Nile Virus will experience severe disease (swelling around the brain or spinal cord) with symptoms of headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, seizures and paralysis. WNV infection is fatal in about 1 percent of diagnosed human cases.

RISK

The risk of getting West Nile Virus depends on how many mosquitoes in the area where you live, or the areas you travel to, are infected. The level of risk also depends on the steps you take to avoid getting bitten by mosquitoes. All residents of areas where virus activity has been identified are at risk of contracting the virus. Persons over the age of 50 and those with weak immune systems are at greatest risk for experiencing severe disease.

AVOIDANCE

It is not possible, nor necessarily desirable, to eliminate all mosquitoes from our environment. By taking steps to avoid getting bitten, we can decrease our chance of being infected with West Nile Virus.

Mosquito Repellants: 

One of the best ways to protect yourself and your family from West Nile Virus is to apply an insect repellant prior to possible exposure to mosquitoes. Products containing DEET (N,N-diethyl-m-toluamide), Oil of Lemon Eucalyptus or Picaridin have been shown to be effective. Note:  recommendations for DEET-containing products are different for adults and children, and users must be aware of important cautions and possible side effects. Be sure to read and follow product directions.

Activity:

Mosquitoes are most active in the early morning hours and early evening hours. To the extent possible, minimize activity in areas likely to have mosquitoes during these times.

Clothing:

Wearing long pants and long-sleeved shirts during peak mosquito hours can decrease the chance of being bitten by mosquitoes. Some outdoor recreation companies sell light weight mesh clothing that is designed to prevent penetration by mosquitoes.

CONTROL

Draining breeding sites:

The number one action you can take on your own property to reduce the number of mosquitoes is to eliminate their breeding sites. As a rule, it takes about a week for mosquitoes to grow from egg to adult. Any standing water, no matter how small the area, can and will produce mosquitoes in that time period. Children’s swimming pools, dog bowls, boat covers, pool covers, roof gutters and leaky faucets are just some of the sources of standing water. Be vigilant in eliminating these sources. Think small.

Chemical treatment:

Chemicals for homeowners are available for personal use. They include permethrin spray to kill adult mosquitoes in lawns and shrubs, methoprene pellets or wafers to kill larvae in standing water or ponds, or bacillus thuringiensis to kill larvae. Those formulations approved for use by the public will be available from local hardware stores or garden centers.

PROTECTING HORSES:

While many horses that become infected with West Nile Virus will not get sick, about one-third to one-half of those showing symptoms will die or be euthanized. Horses exhibit loss of muscle control, difficulty walking, knuckling over, head tilt, muscle tremors and are sometimes unable to stand. Horses are infected through the bite of an infected mosquito. The disease is not passed from animal to animal.

There is a vaccine available to protect horses from West Nile Virus; a newer, improved version was licensed in July 2005. Vaccine may be given by your veterinarian or you can purchase it through farm supply stores. Protection requires two doses to be given the first year, spaced one month apart, followed by yearly boosters after that. Remember that exposure may occur not just where you live, but where you travel with your horses.

Additional Steps to Limit Your Horse’s Mosquito Exposure

-Stable horses during periods of peak mosquito activity

-Turn out stable lights at night