West Nile Virus

Among all people who end up being infected with West Nile virus, the majority of have moderate symptoms that do not get reported. Normally, less than 1% will really develop severe neuroinvasive disease. West Nile virus infection is also called West Nile fever or West Nile sleeping sickness. The infection is a kind of arbovirus (” arbo” originates from ARrthropod-BOrne, as lots of bugs are arthropods). It is a member of the Flavivirus genus and the family Flaviviridae.

West Nile Virus Symptoms

Mild or symptom-free infections prevail with the West Nile infection. Among all people who end up being infected, just two from 10 establish any symptoms. Of those, most just have mild symptoms much like those of the influenza, such as headache, body pains, joint pain, swollen lymph nodes, vomiting, diarrhea, or rash. The symptoms are not severe enough for many people to look for treatment, but tiredness and weakness can last for a number of weeks. Usually, just one in 150 infections result in severe or neuroinvasive (nervous system disease) infections, according to the CDC. Neuroinvasive disease is triggered by infection and inflammation of the surface covering of the brain (meningitis) or deeper infection of the brain itself (sleeping sickness).

Neuroinvasive disease is unusual but more likely to happen in those over age 50. There are two general symptoms of neuroinvasive disease. Meningitis is marked by headache, high fever, and neck tightness. Encephalitis causes these symptoms but might progress to stupor (sleepiness), disorientation, hallucinations, paralysis, coma, tremblings, convulsions, and rarely death. Often basic weak point advancing to finish paralysis takes place, much like polio; this is called acute drooping paralysis.

West Nile virus can have some long-lasting results after severe illnesses. West Nile virus meningitis or encephalitis may result in a prolonged recuperation and rehabilitation period, specifically in the elderly. Amnesia, depression, irritability, and confusion are the most widespread recurring impacts.

Patients might likewise experience trouble walking, muscle weakness, joint pain, tiredness, vomiting, diarrhea, and sleeping disorders. Symptoms in children and babies are basically the like symptoms in adults. Children might experience headache, might have a fever, and may end up being lethargic. Given that a lot of cases of West Nile virus infection are mild, the prognosis for recovery is normally good. In severe cases, death rates are greatest in the elderly.

The incubation period (the time from infection to the development of symptoms) is 5 to 15 days.


The medical diagnosis of West Nile virus infection is confirmed with a blood or cerebrospinal fluid (CSF) test to identify WNV-specific IgM antibodies. A CSF test needs a lumbar puncture (back tap) to obtain a specimen. IgM antibodies represent current infection and are typically noticeable during active or recent infection within three to 8 days after infection, however a negative test within eight days need to still be duplicated if WNV infection is genuinely presumed. Sadly, WNV IgM antibodies can persist for three months or more, so the test may be positive from a previous infection, or a favorable test may be due to cross-reactivity with antibodies to other flaviviruses. Therefore, a positive WNV IgM antibody should be validated by far more specific screening by CDC.

WNV-specific IgG antibodies appear right after the IgM antibodies, and remain present for life, so testing for these antibodies is not helpful for diagnosis of new infection. Nevertheless, it can help figure out previous infection from new infection when an individual resides in an area where WNV is active or has been exposed. For example, a favorable IgG with a negative IgM recommends no existing or active WNV infection. This may help decide whether other causes of illness might be considered.

Is the West Nile Virus Contagious?

The West Nile infection is not contagious. It can not be sent from individual to individual. A person can not get the virus, for example, from touching or kissing a person who has the disease or from a health-care employee who has actually treated someone with the disease. Human beings are called a “dead-end” host for the virus, indicating one that can be infected however whose immune system normally avoids the infection from increasing enough to be passed back to mosquitoes and after that infected other hosts. There likewise is no evidence that an individual can get the virus from managing live or dead infected birds. Nevertheless, preventing skin contact when managing dead animals, including dead birds, is advised. Gloves or double plastic bags must be used to remove and get rid of carcasses.


There is no particular treatment for West Nile virus infection at this time. Intensive encouraging therapy is directed toward the complications of brain infection Anti-inflammatory medications, intravenous fluids, and extensive medical tracking may be required in severe cases. In milder cases, over-the-counter (OTC) painkiller such as ibuprofen (Advil, Motrin) or aspirin might help reduce symptoms of pain and fever. There is no particular antibiotic or antiviral for the viral infection. There is no vaccine to prevent the virus.


Considering that 80% of people who get infected never ever have any symptoms or signs, the total prognosis (or possibility of full recovery) is outstanding. Of the 20% who develop symptoms and signs, many are mild and may last for a week, however they might be left with some level of weak point, tiredness, and problem concentrating for weeks to months. These recurring symptoms are most likely in those over age 50. A questionnaire research study of people infected during the 1999 break out in New York discovered that only 37% reported complete go back to normal by one year after infection. Surprisingly, the possibility of complete recovery does not differ in those who have mild symptoms and signs versus severe disease. Age and overall health before infection is more predictive of an individual’s possibility of recovery. Those over 65 years of age are more likely to be hospitalized, to be released to a house outside the home, and to have actually prolonged recurring results. Those under 65 years of age are more than likely to have complete recovery. Children are least likely to be impacted by neuroinvasive disease or prolonged recurring symptoms and signs.

West Nile Virus Prevention

The list below recommendations can help reduce the risk of becoming infected with the virus:

  • Apply EPA-registered insect repellent sparingly to exposed skin and clothes inning accordance with maker’s directions. An effective repellent consists of 20%-30% DEET (N,N-diethyl-meta-toluamide). DEET in high concentrations (higher than 30%) may cause side effects, particularly in children and babies, but it is safe to use in pregnancy. Prevent items containing more than 30% DEET.
  • Take preventive measures around your home. Repair or set up door and window screens, use cooling, and minimize reproducing sites (get rid of standing water).
  • Spray clothes with repellents including picaridin or DEET since mosquitoes may bite through thin clothes. There are permethrin products that can be used to clothes that will remain effective through a couple of washes. For those who work outdoors or need extended security, permethrin-impregnated clothing is also available.
  • Repellents may irritate the eyes and mouth, so prevent applying repellent to the hands of children. Bug sprays must not be used to really children (under 3 years of age) or babies.
  • B vitamins are not effective repellents versus mosquitoes.
  • Stay inside at dawn, sunset, and in the early night.
  • Use long-sleeved shirts and long trousers when outdoors.
  • There are some repellents with essential oils like geranium oil that may be an option for some people, however there is much less data on duration of defense or reliability of defenses against mosquitoes.
  • Whenever using an insecticide or bug spray, be sure to read and follow the producer’s directions for use, as printed on the item.
  • If somebody finds a dead bird, the CDC advises not dealing with the carcass with bare hands. Contact a local health department for directions for the notice procedure and dealing with the carcass. After logging a report, they may inform you to deal with the bird.
  • Picaridin is a more recent repellent that is effective and about as lasting versus mosquitoes as DEET at the very same concentrations. It has actually been used in Europe and has been readily available in the U.S. since 2005. Unlike DEET, picaridin has no odor, does not damage artificial fabrics and plastics, and is non-greasy.

Last modified: March 10, 2018


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