West Nile Fever: Causes, Symptoms, Daignosis, Prevention and Treatment

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West Nile Fever
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West Nile Fever

• West Nile fever is a zoonotic disease (an animal
  disease affecting humans). Disease is caused by
  West Nile virus (WNV), which is a flavivirus
  related to the viruses that cause St. Louis
  encephalitis, Japanese encephalitis, and yellow
  fever.West Nile virus is mainly transmitted to
  people through the bites of infected mosquitoes.
  West Nile virus (WNV) is maintained in nature by
  transmission between birds and mosquitoes as
  birds are the natural hosts of the virus. Humans,
  horses and other mammals can be infected.West
  Nile fever can cause severe neurological illness
  and death in people, however about 80 of people
  who are infected show no symptoms.

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Causes of West Nile virus (WNV)

• West Nile fever is caused by West Nile virus
  (WNV), belongs to the Japanese encephalitis virus
  (JEV) antigenic complex under family
  flaviviridae.Transmission of disease West
  Nile virus is happened in natural cycle that
  involves transmission between birds and
  mosquitoes. Humans, horses and other mammals can
  be infected.Birds acts both as carriers and
  amplifying host for West Nile virus. Some bird
  species especially the crow family (corvidae) are
  more susceptible to the virus than others.
  Migratory birds are important in West Nile virus
  transmission.

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Causes of West Nile virus (WNV)
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• When mosquitoes feed on an infected bird they
  become infected with the virus. The mosquitoes
  play their role as carriers by spreading the
  virus from an infected bird to other birds and to
  other animals. West Nile virus is maintained in
  mosquito populations by transferring the
  infection through adults to eggs.Infection of
  other animals (e.g. horses, and also humans) is
  incidental to the cycle in birds since most
  mammals do not develop enough viruses in the
  bloodstream to spread the disease. They are
  dead-end hosts.  The virus can be transmitted
  through a direct contact with other infected
  animals, their blood, or other tissues.A small
  proportion of human infections may be transmitted
  from organ transplant, blood transfusions and
  breast milk of infected person.

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Diagnosis of West Nile virus (WNV)

• Various diagnostic tests are-
• (ELISA) IgM can be determined from cerebrospinal
  fluid (CSF) and serum specimens received from
  West Nile virus infected patients at the time of
  their clinical presentation. Serum IgM antibody
  can persist for more than a year.
• IgG antibody sero-conversion in two serial
  specimen collected at a one week interval by
  enzyme-linked immunosorbent assay (ELISA)
• Viral detection by reverse transcription
  polymerase chain reaction (RT-PCR) assay, and
• Virus isolation by cell culture.

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Symptoms of West Nile virus (WNV)

• The incubation period (the period between
  exposure to an infection and the appearance of
  the first symptoms) of West Nile fever is usually
  3 to 14 days.20 of people who become infected
  with West Nile Virus will develop West Nile fever
  whereas about 80 of infected people are
  asymptomatic (show no symptoms).Some of the
  symptoms of West Nile fever involve Fever,
  headache, tiredness, and body aches, nausea,
  vomiting, sometimes skin rash and swollen lymph
  glands.

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Symptoms of West Nile virus (WNV)
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• Severe disease such as West Nile encephalitis or
  meningitis (inflammation of brain and surrounding
  tissues) show symptoms of headache, high fever,
  neck stiffness, stupor, disorientation, tremors,
  coma, convulsions, muscle weakness and
  paralysis.Serious illness can occur in people
  of any age however people over the age of 50 and
  some immune-compromised persons (such as person
  who has received organ transplant) are at greater
  risk of serious illness.It takes several weeks
  or months to recover from serious illness. Some
  of the neurologic effects may be permanent
  resulting in long-term sequelae or death.About
  10 of patients with neurologic complications
  may die.

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Treatment of West Nile virus (WNV)

• Specific antiviral treatment for West Nile virus
  infection is not available. In mild infection
  pain relievers can be used to reduce
  fever.Treatment is supportive involving
  hospitalization, intravenous fluids, respiratory
  support, and prevention of secondary infections
  for the patients who are suffering with
  neuro-invasive west Nile virus infection. No
  vaccine is available for humans.

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