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West Nile Virus

West Nile Virus (WNV) is a zoonotic disease that affects animals, but can also affect humans. A member of the flavivirus genus, WNV belongs to the Japanese encephalitis antigenic complex of the family Flaviviridae. 

Birds are the instinctive host of the West Nile virus. Mosquitos develop the virus by biting the infected birds. Most human cases of WNV are by mosquito bites. 

Other than humans, this virus can affect horses and many other species of birds. Generally, West Nile virus spreads to humans and animals from bites of infected mosquitoes. Mosquitoes get infected after biting infected birds and carry this virus.

West Nile Virus in Humans

In 1951 the first human being was affected by West Nile Virus (WNV)  in Israel. Commonly found in West Asia, the Middle East, Europe, Africa and North America, WNV can cause neurological disease and even death in affected people. It is maintained in nature in a cycle involving transmission between mosquitoes and birds. Humans, horses as well as other mammals can be infected.

People of old age and people with a chronic disease like diabetes or cancer have a higher risk from the disease. However, the chances of severe illness are less. People facing severe symptoms recover completely.

Symptoms

Eighty percent of people infected do not feel any symptoms. 

Out of the rest of the 20%, few of the infected people feel mild symptoms. These symptoms are almost the same as any other  viral fever. Mild symptoms of West Nile virus include:

  • Fever
  • Nausea
  • Headache
  • Skin rash
  • Fatigue
  • Body ache

The symptoms of severe disease, which is also named as neuroinvasive disease like meningitis or West Nile poliomyelitis or West Nile encephalitis, include: 

  • Headache
  • High fever
  • Neck stiffness
  • Stupor
  • Disorientation
  • Coma
  • Tremors
  • Convulsions
  • Muscle weakness
  • Paralysis 

It is projected that about 1 in 150 persons infected with WNV may develop a more severe form of this disease. While severe illness can occur in people of any age, those over the 50 years of age and some immunocompromised individuals (Eg. transplant patients) are at the greater risk for getting severely sick when infected with WNV.

Risk Factors

Those who have a weak immune system due to any reason do have more risk of getting severe symptoms of WNV.

Travelers visiting endemic areas are at risk of catching the virus, along with people over 60 with a weakened immune system. People with other diseases like cancer, high blood pressure, or diabetes are also at higher risk.

When to see a doctor

Mostly there is no need for a consultation. Mild symptoms will most likely go away by themselves. If you feel any of the severe symptoms mentioned above, then make an appointment with your physician right away.

West Nile virus can be detected using numerious different tests, which may include:

  • Neutralisation assays 
  • IgM antibody capture ELISA (enzyme-linked immunosorbent assay)
  • IgG antibody sero-conversion (or significant surge in antibody titers) in two serial specimen collected at a 1-week interval by ELISA (enzyme-linked immunosorbent assay)
  • Viral detection by RT-PCR (reverse transcription polymerase chain reaction) assay
  • Virus isolation by cell culture.

IgM can be diagnosed in almost all CSF (cerebrospinal fluid) and serum specimens taken from the WNV infected persons at the time of their clinical presentation. Serum IgM antibody can persist for over an year.

If the doctor suspects any neurological damage due to the disease, he/she may order an MRI or EEG to measure the brain’s activity and find out if there is any inflammation.

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Prevention

The maximum chance of catching the West Nile virus is by a mosquito bite.

There are no preventive medications for the virus. Some of the other preventive measures one can take are,

  • WNV is commonly found in Africa, North America, Europe, West Asia, and the Middle East, so people living there or traveling there should be extra careful.
  • Use mosquito repellent sprays or gel while going out.
  • Wear full-length clothes to cover your skin.
  • Don’t leave water unused or contaminated.
  • Wear neutral colors and apply sunscreen before stepping out.
  • Get your windows netted to stop mosquitoes from entering your house.

Mosquitos have trouble surviving in winters, so these precautions should be taken more seriously during the summer.

Treatment

Most cases of the West Nile virus do not require any treatment. Severe cases may require hospitalization.

There is no cure or vaccine specifically for humans as of now. If you consult a doctor, he/she might provide medications for  specific symptoms like pain killers for body aches and medication to reduce fever

Conclusion

There is no vaccine for the West Nile virus right now, but it can be prevented .

The odds of the diseases getting serious are very less, and you might recover very quickly. If the mild symptoms are making you uncomfortable, then a few medications can be very helpful.

If the symptoms are getting worse, seeing a  a doctor as soon as possible and taking the right step might promise a complete recovery and no post disease symptoms.

If you are feeling any of the severe symptoms mentioned above, see a doctor now.

Frequently Asked Questions

Can you die from the West Nile virus?

Less than 1% of the people affected by the virus face severe symptoms. Chances of death through WNV are very slim, but it is possible.. Also, age plays a role as more severe cases are seen in people over 60.

Is WNV contagious?

No, the West Nile virus cannot be transmitted from human to human. The disease originates from birds and is transferred to humans through mosquitos.

Can pet dogs and cats catch the virus?

Dogs and cats can be affected by the virus. However, they cannot transmit it to people. There are very few chances of animals not recovering from the virus. Most of them, if in a healthy condition, recover very quickly.

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