"Encephalitis" is an inflammation of the brain, sometimes caused by viruses and bacteria. West Nile is one of four mosquito-borne viruses found in Louisiana, which can cause such an infection. The others are LaCrosse, California and Eastern equine encephalitis. It is also closely related to the St. Louis encephalitis virus, found in the United States. The virus has probably been in the eastern U.S. since early summer of 1999, possibly longer. It is now permanently established in the Western Hemisphere.
The incubation period in humans for West Nile encephalitis is usually 3 to 15 days. There is no vaccine against West Nile encephalitis.
The risk of contracting a serious illness after West Nile virus infection is slim. Only 1 in 5 people infected will develop any symptoms at all, while 1 in 150 infected individuals will suffer more serious complications.
Individuals over 50 years of age and people with weak immune systems tend to be hardest-hit by West Nile virus infection. Fatality rates among those with severe illness due to West Nile virus range from 3% to 15%. Less than 1% of persons infected with West Nile virus will develop severe illness.
West Nile encephalitis is NOT transmitted from person-to-person. Infected mosquitoes are the primary source for West Nile virus. In southern climates, where temperatures are milder, West Nile virus can be transmitted year round.
Mosquitoes become infected when they feed on infected birds. They transmit the virus to humans and animals, while biting to take blood. Following transmission by an infected mosquito, West Nile virus multiplies in the person’s blood system and crosses the blood-brain barrier and enters the brain. The virus interferes with a normal central nervous system functioning and causes inflammation of brain tissue.
The mosquito-borne disease can cause mild flu-like symptoms and, more rarely, encephalitis. Symptoms include fever, headache, and body aches, occasionally with skin rash and swollen lymph glands. More severe infection may be marked by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis, and rarely, death.
Steps to Take
The most important thing you can do to protect yourself against this virus is to avoid mosquito bites. The following list of actions should help:
· Stay indoors at dawn, dusk, and early evening.
· Wear long-sleeved shirts and pants outdoors.
· Apply insect repellent sparingly to exposed skin and thin clothing. An effective repellent will contain 35% DEET (N,N-diethyl-meta-toluamide). DEET in high concentrations (greater than 35%) provides no additional protection.
· Repellents may irritate the eyes and mouth, so avoid applying repellent to your child’s hands (Please note: Children should not be exposed to insect repellent containing 10% DEET or more.) Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer’s DIRECTIONS FOR USE, as printed on the product.
· Install or repair window and door screens, so that mosquitoes cannot get indoors.
· Note: Vitamin B and "ultrasonic" devices are NOT effective in preventing mosquito bites. · Empty anything outdoors that could collect water, such as children’s toys, flower pots, birdbaths, etc. since any collection of water can serve as a breeding ground for mosquitoes.
· If you develop a fever with a stiff neck, headache or confusion, call your doctor to determine if further evaluation is needed.