West Nile Virus

Description of virus that causes the disease.

  • virons consist of an envelop and a nucleocapsid
  • virons are spherical and measure 40-50 nm in diameter 
  • the envelop has surface projections
  • the core is isometric and has a diameter of 25-30 nm
  • the capsid shells of virons are single layer

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West Nile Virus


Viral Specificity:

  • its a illness that is spread from mosquito's to humans
  • the mosquito bites the host and transmits the virus into the blood
  • it cannot be passed from human to human
  • the virus travels through the blood stream and affects the different organs in the human body
  • it affects the central nervous system

Symptoms and progression of the disease:

West Nile virus produces three different outcomes:
  • asymptomatic infection
  • mild febrile syndrome (West Nile Fever)
  • neuroinvasive disease (West Nile meningitis or encephalitis)
  • the ratio for these three stages is roughly 110:30:1
The second febrile stage has an incubation period of 2 to 8 days
symptoms of this stage include:
  • drowsiness, pain in joints, rash, swollen lymph node, weakness
  • headache, chills, diaphoresis,
  • symptoms usually resolve within 7 to 10 days
  • fatigue can persist for weeks
  • swollen lymph nodes can last up to 2 months
Rarer outbreaks (encephalitis)
  • similar early symptoms but also decreased level of consciousness
  • spinal cord could get infected
  • hepatitis, myocarditis, nephritis, pancreatitis
  • recovery is long

Common Methods of Transmission:

  • The virus is transmitted through mosquito's vectors
  • mosquito's feed on infected birds
  • s get West Nile Virus form Birds
  • infected mosquito's feed on humans
  • Asian tiger mosquito has been found to be a vector of WNV
  • virus does not multiply as readily in mammals
  • mammals are dead-end infection (doesn't spread any further)

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Treatment and Prevention (if any):

  • AMD3100 this drug was originally made for HIV but has shown promise against WNV encephalitis
  • there have been attempts to use ribavirin, intravenous immunoglobulin, or alpha interferon to treat infections
  • There is no vaccine for WNV
  • minimize your time out doors when mosquito's are most active
  • where long sleeve shirts
  • use insect repellent
  • make sure your screens on doors and windows are put on tight
  • reduce mosquito's breeding areas (clean out any small pool of water)

Miscellaneous:
  • WNV emerged as a distinct virus around 1000 years ago
  • WNV was posted as one of the possible cause of Alexander the Greats death
  • WNV was first isolated from a feverish 37 year old women in the West Nile District of Uganda in 1937
  • The first appearance of WNV was in the western hemisphere was in 1999
  • A high level of media coverage through out 2001/2002 raised public awareness
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Resources accessed:

Wikipedia
CBC News-health-West Nile Virus
www.ictvdb.org