West Nile Fever

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West Nile Fever
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West Nile Virus

• First seen in 1937 in Uganda, Africa
• Flavivirus (other strains cause St. Louis
  fever,Murray Fever, etc)
• Outbreaks have occurred in the Middle East
  (Israel), West Asia, Eastern Europe and Africa

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• First seen in the US in 1999 (New York).
• Mosquitoes are the vector, usually occurs August
  to October (not all species of mosquitoes can
  transmit)
• Birds are the carrier host (particularly
  migratory birds). Arbovirus
• (black birds, crows, blue jays, cardinals die
  from WNF, others such as house sparrows dont)
• Humans and horses are dead end hosts.

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Horses or Humans Dead end host
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• Virus causes inflamination of the mengies in the
  brain, symptoms similar to encephalomyelitis.
• Horses are the most susceptible, 20 to 30of the
  horses infected with West Nile Fever die.
• Humans rarely die if treated
• WNV will always be here, can only control it.
• 7 day incubation period for the virus

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Symptoms of West Nile Fever

• Horse
• Depression, loss of appetite
• Fever- may or may not see, may see subnormal
  temperature.
• Staggering gait, paralysis, coma, death
• Human
• Flu like symptoms, headache, swollen glands
• Fever, rash may develop, muscle weakness
• Disorientation, paralysis, coma, convulsions

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• Cannot get by contact with infected animals,
  mosquito must transmit
• Fourteen day incubation period.
• Treatment is supportive ( fluids, rest,
  antibiotics to prevent secondary infection, etc).

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Prevention

• Control mosquitoes
• Make sure water sources that mosquitoes breed in
  are removed ( rain gutters, water tanks, old
  tires, etc)
• Mosquitoes are the most active in the early
  morning and at dusk.
• Vaccinate
• Fort Dodge has a new killed vaccine, not known
  yet how good the vaccine is, still testing.
• At this time should use vaccine even though
  effectiveness is not known, it is all we have
  available.

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Mosquitoes

• Over 60 species of mosquitos
• Not all species bite people
• Most consume nectar as their energy source, only
  consume blood for egg laying ( why males dont
  bite)
• Mosquitoes live 7 to 10 days,3 day cycle between
  blood meal and egg laying

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• Number 1 killer of mosquitos is age, No.2 is the
  sun (why most feed early,late and at night)
• Can travel up to 12 miles
• Mosquitoes see in the blue ultraviolet spectrum
• Attracted by aromas and heat
• Attracted by carbon dioxide

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• For additional information
• http//www.aphis.usda.gov/oa/wnv/index.html