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Introduction to West Nile Virus Awareness Training

 

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West Nile Virus:

Virus Transmission Cycle

 




 

Reservoirs and Clinical Description

 

Reservoirs:

  • Birds are considered to be the main vertebrate host. Over 70 species of birds (mostly crows) tested positive
  • Clinical signs have been observed in horses
  • Cattle, Sheep, Camels can be infected, but viremia capable of infecting vectors has not been reported

 

Classical Clinical Description

Other Clinical Information



 

Most illnesses are manifested by "West Nile Fever"

 

Severe neurologic illness categories

 

Movement Disorders

Tremor:  a rhythmic, involuntary muscular contraction characterized by a to-and-from movements of a part of the body.



Myoclonus:  brief, involuntary twitching of a muscle or a group of muscles.

Both tremor and myoclonus—onset generally > 5 days following initial symptoms

Rhabdomyolysis—acute destruction of skeletal muscle cells

 

 

 

Spread of West Nile Virus in the
United States

 

Spread on WNV in the US

Cases of WNV In the US

 

 

 

 

West Nile Virus Program

 

WNV Program Elements

Surveillance

  • Dead bird
  • Mosquito

Control

  • Chemical
  • Mechanical
  • Cultural

Education/Communication


 

Surveilance

 

Dead Birds

Larvae breeding sites


 

Control

 

Larval Control

Reduction of Mosquito Breeding Sites

Eliminate standing water and containers

  • Tires and tire swings
  • Flowerpots
  • Pet dishes
  • Bird baths
  • Clogged rain gutters


Mosquito Control

Personal Protective Measures

  • Long Sleeves
  • DEET
  • Limit outdoor activities at dawn, dusk, and early evening
  • Repair holes in door and window screens


 

 

 

 

Identification of Mosquito Adults

 

Mosquitoes Positive for WNV

  • Culex pipiens
  • Cules restuans
  • Culex salinaruius
  • Aedes vexans
  • Aedes cantanor
  • Ochlerotatus triseriatus
  • Ochlerotatus japonicus
  • Aedes albopictus
  • Anopheles punctipennis
  • Psorophora ferox
  • Culiseta melanura


 

Not all may be competent vectors!

Communication And Education

 

Education

  • Most mosquitoes are not infected with West Nile Virus
  • Most mosquito bites will not lead to a West Nile Virus infection
  • Most people who become infected do not get sick
  • In US outbreaks, fewer than 1% of infected people became seriously ill
  • Children are not in a higher risk group
  • Older people and the immuno-compromised have greater risk of becoming seriously ill
  • There is no vaccine or medication specific to WNV—treat the symptoms

Communication

Medical should closely liaise with:

  • Local or State Health Departments
  • Base Pest Control
  • Local or State Mosquito Control Districts
  • U.S. Army Veterinary Services

Information resources

  • State and local Mosquito Abatement Districts
  • State and local Health 1-800-871-9703
  • CDC Website: www.cdc.gov
  • USGS Website: www.usgs.gov

 

 

 

 

 

 

 

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