Introduction
The West Nile virus was first identified in 1937 in a woman in the West Nile district of Uganda. It was isolated in birds in 1953 in the Nile delta region. In 1997 a more virulent strain of the virus caused the death of different species of birds; since then, the virus has been considered pathogenic for birds. Human infections were reported in many countries, and the largest outbreak occurred in Israel, Romania, Greece, Russia, and the USA. And the sites of outbreaks were noticed to be on major birds' migratory routes. The virus is commonly found in Europe, North America, Africa, and West Asia.
What Is West Nile Fever?
West Nile fever is an illness contracted from infected mosquito bites. The West Nile virus can infect birds, horses, and other mammals. The disease is expected in late summer and late fall in mild zones. However, it may also occur throughout the year in southern climates. It is associated with malaise, headache, myalgia, rashes, and lymphadenopathy; and may resemble the flu.
What Causes West Nile Fever?
The West Nile virus causes West Nile fever. It is a flavivirus that is transmitted through infected mosquitoes. Birds are the natural hosts of the virus and are maintained in nature by the spread between birds and mosquitoes. The West Nile virus replicates faster and spreads faster to birds at higher temperatures; one of the reasons is that climate changes impact the epidemiology of the infection. West Nile fever is the mild form of a West Nile virus infection.
How Does West Nile Fever Spread?
The West Nile virus spreads to humans through the bite of an infected mosquito. The mosquito gets infected by biting infected birds; birds are the natural hosts of the virus. When these mosquitoes bite humans, it causes the transmission of the virus. The virus may also spread through blood transfusions, breastfeeding, pregnancy, or organ transplants; however, this is rare. The virus does not spread through direct contact with an infected person.
What Are the Risk Factors for West Nile Fever?
Although anybody bitten by an infected mosquito can get west Nile fever, less than one percent of people develop severe symptoms. The risk factors for the infection may include age, as people above 60 years are more susceptible to the illness. Underlying medical conditions like hypertension, diabetes, cancer, impaired immunity, and kidney problems can also increase the risk of having severe symptoms. The virus is more prevalent in males.
What Are the Signs and Symptoms of West Nile Fever?
Almost 80 percent of people infected by the West Nile virus show no symptoms, and about 20 percent may develop West Nile fever. The symptoms appear 3 to 14 days after the bite and may last weeks or months. Symptoms include:
-
High fever.
-
Chills.
-
Headache.
-
Body ache.
-
Skin rashes, especially on the trunk.
-
Swollen lymph glands.
-
Excessive sweating.
-
Weakness.
-
Fatigue.
-
Drowsiness.
-
Joint pain.
-
Nausea.
-
Vomiting.
-
Loss of appetite.
-
Diarrhea.
What Are the Other Illnesses Caused By West Nile Virus?
The West Nile virus can cause severe conditions like encephalitis and paralysis; in rare cases, it may even cause permanent brain damage and sometimes death.
-
West Nile Neuroinvasive Disease: It occurs when the virus infects the CNS (central nervous system).
-
West Nile Encephalitis: It is similar to viral encephalitis, and symptoms include fever, headache, muscle weakness, flaccid paralysis, and altered mental status.
-
West Nile Meningitis: It involves symptoms like neck stiffness, headache, fever, and pleocytosis (an increased amount of white blood cells in the body).
-
West Nile Meningoencephalitis: It is the inflammation of the meninges and the brain.
-
West Nile Poliomyelitis: It is less common and is associated with the acute onset of asymmetric limb weakness, pain, and paralysis without sensory loss.
-
West Nile Reversible Paralysis: It is characterized by asymmetric paralysis or weakness.
Nonneurologic Complications: These include;
-
Pancreatitis (inflammation of the pancreas).
-
Myocarditis (inflammation of the heart muscle).
-
Hepatitis (inflammation of the liver).
-
Rhabdomyolysis (breakdown of muscle tissues).
-
Orchitis (inflammation of the testicles).
-
Optic neuritis (inflammation of the optic nerve).
-
Nephritis (inflammation of the kidneys) and hemorrhagic fever with coagulopathy.
-
Skin Manifestations: It includes red maculopapular rashes on the extremities.
How Is West Nile Fever Diagnosed?
The healthcare provider may advise a blood test to check for the presence of the West Nile virus or the antibodies against the infection. In case of severe conditions of the West Nile virus that is brain-related, the physician may advise a lumbar puncture or the spinal tab test. The test includes inserting a needle into the spine and extracting the fluid. The fluid is then sent to the laboratory for testing, as the virus can increase the white blood cells in the spinal fluid. In addition, other tests like MRI (magnetic resonance imaging) can help detect brain inflammation.
What Is the Treatment for West Nile Fever?
West Nile virus infection does not have a specific cure. However, most people recover without treatment. Over-the-counter (OTC) medications such as Aspirin or Ibuprofen can help relieve headaches and muscle pain. In severe cases, hospitalization for supportive care with intravenous fluids, pain medication, respiratory support, and prevention of secondary infection is needed.
How Can West Nile Fever Be Prevented?
West Nile virus spreads to humans through the bite of an infected mosquito; since there is no treatment or vaccine for the disease, preventing mosquito bites can help protect oneself from the disease.
-
Use insect repellents that are environmental protection agency-registered with DEET (N, N-Diethyl-meta-toluamide), Picardin, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone when going out.
-
Put on completely covered clothing for babies and young children.
-
Use a mosquito net to cover strollers and baby carriers.
-
If one uses sunscreen, apply it first and the insect repellent over it.
-
Do not let standing water anywhere around the house.
-
Wear full-sleeved clothing.
-
Install mosquito screens on the windows and doors of the house.
-
Use mosquito nets around the beds, cribs, and playpens.
-
Treat the clothes and gear with 0.5 percent Permethrin.
Conclusion
West Nile fever is a febrile illness caused by the West Nile virus. The virus is spread through infected mosquitoes that get the virus from infected birds. It is the mild form of the manifestations of the virus and resembles the flu, and usually subsides without any treatment. However, over-the-counter medications can help relieve the symptoms. In addition, preventing mosquitoes around the house and while going out can help prevent the illness.
