WEST NILE VIRUS (WNV)

About: 

• Genus: West Nile Virus (WNV), a mosquito-borne disease, is a member of the flavivirus genus and belongs to the Japanese encephalitis antigenic complex of the family Flaviviridae. 
  
  
• Vulnerable species: WNV is maintained in nature in a cycle involving transmission between birds and mosquitoes. Humans, horses and other mammals can be infected. 
  
  
• Distribution: WNV is commonly found in Africa, Europe, the Middle East, North America and West Asia. 
  
  
• History: West Nile Virus (WNV) was first isolated in a woman in the West Nile district of Uganda in 1937. Human infections attributable to WNV have been reported in many countries in the World for over 50 years. 
  
  
• Transmission: 
  • Human infection is most often the result of bites from infected mosquitoes. The virus may also be transmitted through contact with other infected animals, their blood, or other tissues. 
    
    
  • To date, no human-to-human transmission of WNV through casual contact has been documented. 
    
    
  
  
  
• Signs and symptoms: 
  • Approximately 80% of people who are infected with WNV will not show any symptoms. 
    
    
  • About 20% of people who become infected with WNV will develop West Nile fever or severe West Nile disease (also called neuroinvasive disease, such as West Nile encephalitis or meningitis or West Nile poliomyelitis). 
    
    
  • West Nile virus can cause a fatal neurological disease and death in humans and horses. 
    
    
  
  
  
• Treatment and vaccine: 
  • Treatment is supportive for patients with neuro-invasive West Nile virus, often involving hospitalization, intravenous fluids, respiratory support. 
    
    
  • Vaccines are available for use in horses but not yet available for people.