West Nile Virus
West Nile Virus
What is West Nile virus? West Nile virus (WNV) is a flavivirus commonly found in Africa, West Asia and the Middle East. The virus can infect humans, birds, mosquitoes, horses, and some other mammals. WNV was introduced in America in 1999.
What are the symptoms? Most people who are infected with WNV will not have any type of illness or may experience mild fever, headache, and body aches before fully recovering. If illness were to occur, it would typically occur within 3-14 days of being bitten by an infected mosquito. It is estimated that 20 percent of people who become infected develop West Nile fever: mild symptoms include fever, headache and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands. In a very few individuals, particularly the elderly, WNV can affect brain tissue, cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and the spinal cord), but more commonly presents as a febrile illness. Symptoms of encephalitis include rapid onset of severe headace, high fever, stiff neck (in meningitis), muscle weakness, confusion and loss of consciousness.
How is it spread? Certain species of birds (corvids) tend to carry the virus and only certain species of mosquitoes become infected when they feed on infected birds or horses. Most commonly, the virus is transmitted to people when an infected mosquito bites a human. WNV is not spread by person-to-person contact or by caring for someone who is infected. In a few individuals, it may have been spread through blood transfusions, but screening tests are being put in place.
How is it treated? There is no vaccine for WNV, nor is therre any specific therapy. In severe cases, hospitalization, intravenous (IV) fluids and nutrition, airway management, ventilatory support (ventilator) if needed, prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care are required. At its most serious, it can cause death; however death from the disease is rare.
Should I be concerned about getting it? The chances you will become ill from any mosquito bite are very remote. In areas where the virus has been detected, very few mosquitoes in that area will carry it. Less than one percent of people who become infected will get severely ill. Most severe cases, such as encephalitis or meningitis, have occurred in people over 50 years of age.
What should I do if I think I have WNV? If signs and symptoms of encephalitis or meningitis are present, seek medical care immediately. Any level of the disease should be confirmed and reported to local health authorities.
Can my pets get WNV? Other than horses, WNV in pets is rare. There is a vaccine available that provides horses and other equines some protection against WNV. Onwers of these animals should have them vaccinated twice per year.
What can I do to protect myself and my family? Follow the "4 D's" for prevention and protection:
- Dusk/Dawn are the times of day when mosquitoes are most active, so you should try to stay indoors during those times.
- Dress in long sleeves and pants when you are outside. For extra protection, you may want to spray thin clothing with insect repellent.
- DEET is an ingredient to look for in your insect repellent. Always wear repellent when outdoors and choose products that contain up to 20 percent DEET (10 percent DEET for children).
- Drain standing water in your backyard and neighborhood. Old tires, flower pots, trash cans that are left uncovered, and clogged rain gutters are just a few of the sites that mosquitoes use to breed.
How do I treat stagnant water? Since stagnant water is a prime breeding ground for mosquitoes, it should be drained immediately if possible. If the stagnant water is in a pond or large drainage area that cannot be drained, the use of mosquito "dunks" is the most effective treatment. "Dunks" are small, round (often doughnut shaped) disks of larvaecide that kill mosquitoes in their larvae stage, before they become flying adults. "Dunks" may readily be purchased at home improvement and athletic supply stores.