West Nile virus

What is West Nile virus?

West Nile virus (West Nile fever) causes an infection that is spread by certain types of mosquitoes. Mosquitoes are most often infected when they bite infected birds. Mosquitoes then spread the virus when they bite humans or other animals such as horses. The virus cannot be transmitted from these animals to humans or from an infected person to a healthy person through casual contact.

The virus is picked up by an organ transplant or a blood transfusion. Therefore, when donating blood, the blood is tested for the presence of the virus. Some data indicate that an infected mother can transmit the virus to her child during pregnancy and at birth or through breast milk.

However, experts recommend that infected women breastfeed their children, as the risk of spreading the virus in these ways is not well studied, and the benefits of breastfeeding are widely known.

Most people who are infected with the virus have no symptoms. Or the symptoms of the infection may be so mild that people may not even realize they have a viral infection.

In rare cases, the infection can lead to inflammation of the brain /encephalitis/ or spinal cord /myelitis/. It is also possible that the virus can cause swelling of the brain membranes /meningitis/.

Anyone who is bitten by a mosquito can become infected with West Nile virus. Most patients with the viral infection recover completely after a while.

But it is also possible to develop complications such as seizures, memory loss and brain damage, especially in children and the elderly. As those over 70 years of age have the greatest risk of death from the infection.

What are the symptoms of West Nile virus

In about 80% of cases, patients with West Nile fever have no clinical manifestations. If symptoms appear, it occurs 3 to 14 days after the mosquito bite. Mild symptoms are:

• Fever;
• Headache, body or eye pain;
• Rash, usually on chest, back and arms;
• Feeling fatigue;
• Loss of appetite;
• Nausea or vomiting;
• Increased lymph nodes in rarer cases;

In in milder cases, symptoms usually subside in about 3-6 days. But if the more severe form of the viral infection develops, the clinical manifestations can last for weeks or even months. In more severe cases, when the virus affects the brain and spinal cord, the characteristic symptoms of such complications are:

• Severe headache and very high temperature above 40 degrees Celsius;
• Neck stiffness or paralysis;
• Confusion and decreased sensitivity;
• Tremors, convulsions or muscle weakness;
• Coma;

In rare cases, the virus can cause death.

Treatment of West Nile fever

There is no specific treatment for this type of viral infection. The infected person’s body must fight the infection with the help of its immune system. If you have a mild form of the clinical condition, you can recover at home. But if the West Nile virus infection is severe, hospitalization may be necessary.

How to protect yourself?

You can reduce the risk of infection if:

• Use insect repellent when going outdoors from late spring to early fall.
• Wear long-sleeved blouses and shirts and long pants when walking in humid forested areas, urban parks, rivers, etc.
• Do not leave open containers of water near your home because mosquitoes are attracted to stagnant water.
• If possible, stay indoors at dawn and dusk and early evening when mosquitoes are most active.

There are suggestions that West Nile fever has also been used as a biological weapon in several conflicts, including the 2003 overthrow of Saddam Hussein when applied by Iraq against the US. The development is based on the strain SV 1417.