West Nile Virus
Originally diagnosed in Uganda on the banks of the Nile river in the 1930s, West Nile virus made its first appearance in the western hemisphere in New York City in 1999. Since that time, the disease has become increasingly prevalent in the United States and there have been several severe outbreaks. Commonly, West Nile virus is contracted through bites by infected mosquitoes who have themselves contracted the illness from infected birds. Although 70 to 80 percent of people who harbor the virus do not become ill, the illness can, especially in older and immune-compromised patients, be dangerous and even fatal. In this century, there have, at times, been an alarming number of deaths attributable to the virus.
Transmission of West Nile Virus
While West Nile virus is most commonly transmitted to humans by mosquitoes, it can also, albeit rarely, be spread through:
- Blood transfusions
- Organ transplants
- Laboratory exposure
- Maternal transfer during pregnancy, delivery, or breastfeeding
Outbreaks of West Nile virus are most common during the summer and early autumn. Although dead birds are sometimes an indicator of the presence of the disease in the area, humans cannot contract the disorder from birds, dead or alive.
Symptoms of West Nile Virus
As mentioned, most people have no symptoms from West Nile virus. About 20 percent of those infected develop symptoms after 3 to 14 days.
Mild Symptoms
Most patients who become ill from West Nile virus experience unpleasant, but relatively mild, symptoms that may include:
- Fever
- Headache
- Body aches and joint pains
- Vomiting and diarrhea
- Rash, eye pain, swollen glands (sometimes)
While the majority of individuals who develop these viral symptoms recover completely, they may experience weakness and fatigue for weeks or even months.
Severe Symptoms
Only 1 percent of patients who contract West Nile virus develop neurological symptoms, but, for those who do, the illness is life-threatening. Most of the time, these patients are elderly or suffer from serious underlying conditions, like diabetes, cancer, or kidney disease, that weaken their immune systems.
In susceptible individuals, West Nile virus can result in encephalitis or meningitis, neurological inflammations that can cause:
- High fever
- Severe headache
- Stiff neck
- Respiratory difficulties
- Confusion or disorientation
- Tremors or seizures
- Paralysis
- Coma
For 10 percent of patients afflicted with severe symptoms of West Nile virus, the disease is fatal. For the others, encephalitis or meningitis can last for weeks and there may be residual permanent neurological damage.
Diagnosis of West Nile Virus
To diagnose West Nile virus, blood tests to detect antibodies are performed. CT and MRI scans, as well as lumbar punctures (spinal taps) to test cerebrospinal fluid may also be performed. Recently the FDA has approved a laboratory test known as IgM Capture ELISA for use in patients with symptoms of viral encephalitis or meningitis. This test appears to give accurate results from about a week after the illness is contracted.
Treatment of West Nile Virus
At present there is no vaccine to prevent West Nile virus and no medication to cure it. For mild cases, over-the-counter products to reduce fever and other symptoms may be all that is necessary. For severe cases, hospitalization is required so that patients can receive more intensive supportive treatment, including intravenous hydration and prescribed pain medication.
Prevention of West Nile Virus
The only way to prevent West Nile virus is to avoid mosquito bites. Methods of protection include:
- Using insect repellent containing DEET
- Wearing long sleeves, pants and socks outdoors, especially at dawn or dusk
- Spraying permethrin on clothing or bedding used outdoors
- Keeping window and door screens repaired
- Emptying any standing water around the home
It is also important to support local mosquito control programs and to report dead birds to local authorities.