West Nile Virus home
What is West Nile virus?
West Nile virus (WNV) can cause a disease called encephalitis, or a brain infection in humans. Infected mosquitoes pass the virus onto birds, animals and people.
WNV cases occur primarily in the late summer or early fall, although mosquito season is usually between the last frost of spring and the first hard frost of fall. WNV can only be spread by mosquitoes after they feed on infected birds and then bites people or animals, not by person-to-person contact, or bird-person contact.
Who is most at risk?
People over 50 years of age have the highest risk of developing severe illness. People with compromised immune systems are also at risk. However, anyone can get the virus.
What are the symptoms?
Some people may be infected, but do not become ill. Others have mild infections with fever, headache, body aches, skin rash and swollen lymph glands. People with more severe infections may experience high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions and paralysis. If you have any of these symptoms, contact your doctor.
Can animals get sick with West Nile disease?
Yes, horses can develop serious illness. About 1/3 of ill horses die or are euthanized. Domestic poultry may become infected, but they usually do not become sick and do not die.
Is there treatment?
There is no specific treatment for WNV infection. While most people fully recover from the virus, in some severe cases hospitalization may be needed.
What should be done to control mosquitoes?
The main thing is to reduce potential mosquito breeding sites. Eliminating places for mosquitoes to breed is an important part of pest management and, whenever possible, is the preferred method of mosquito control.
Is my farm a mosquito-breeding site?
Several habitats found on farms can support the production of mosquitoes. Larvae can develop in watering troughs, small ponds, irrigation ditches, rain barrels, manure lagoons, ruts where farm equipment frequently travels and other areas where water is allowed to accumulate. Even hoof prints can accumulate water and provide a breeding habitat. The close proximity of livestock, nuisance animals (such as birds) and other animals to mosquito breeding habitats increases the risk for the transmission of animal and human disease.
How can I prevent mosquitoes from breeding?
You should improve drainage in irrigated fields, and fill in ruts made by tractors and other farming equipment.
Make sure you thoroughly clean watering troughs regularly. Remove containers that accumulate water, including old tires. Aerate small ponds and stock them with native fish that eat mosquito larvae such as fathead minnows and killifish minnows.
In situations where eliminating mosquito breeding areas is not a practical alternative, larviciding is the most effective control technique. Several larvicides are well suited for farms, including Bacillus sphaericus, B. thuringiensis israelensis (B.t.i), Temephos, growth regulators, oils and monomolecular films. These larvicides can only be applied by certified pesticide applicators. An applicator can help you to determine which product would best suit your situation, and what type of control activities should be conducted.
How can I protect myself?
It is not necessary to limit any outdoor activities, unless local officials advise you otherwise.
However, you can and should try to reduce your risk of being bitten by mosquitoes. In addition to reducing stagnant water in your yard, make sure all windows and doors have screens, and that all screens are in good repair. If WNV is found in your area:
Electromagnetic and ultrasound devices and Vitamin B are not effective in preventing mosquito bites.
