West Nile Virus

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Signs and symptoms, epidemiology, treatment, prevention of WNV

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West Nile Virus

  1. 1. West Nile Virus (WNV)<br />Microbiology – Alison Lederer – Aurora University (Fall 2008)<br />
  2. 2. CDC<br />Cause<br />Infection of West Nile virus during blood-feeding of Culex or Aedes mosquitoes<br />West Niles virus under<br />electronmicroscope<br />Culex mosquito<br />
  3. 3. 3 Possible Degrees<br />Sub-Clinical:<br />Fever<br />Headache<br />Fatigue<br />Fatal:<br />High fever<br />Severe headache<br />Nausea and <br />vomiting<br />Stiff neckSeizuresProfound muscle <br /> weakness<br />Asymptomatic<br />Signs and Symptoms<br />Encephalitis: inflammation of the brain<br />ViremicPeriod – 7 days<br />
  4. 4. Treatment<br />There is no cure for WNV<br />Most treatments are aimed at retaining bodily function of fatally infected individuals<br />Maintaining fluid levels (IV)<br />Ventilator treatments<br />Antibiotic injections to eliminate secondary and opportunistic diseases<br />Vaccination for WNV is in research and development stages<br />(Sfakianos 2005)<br />
  5. 5. Transmission<br />Mosquitoes<br />Vector blood-feeding<br />Instantaneous infection from simultaneous feeding<br />Mosquito vertical transmission<br />Culex mosquito<br />Turdus migratorius<br />(Kilpatrick 2007)<br />
  6. 6. Transmission<br />Birds <br />Birds living past 8 days develop both specific and general defense to flaviviruses<br />Horizontal transmission<br />Culex mosquito<br />Turdus migratorius<br />(Kilpatrick 2007)<br />
  7. 7. Transmission<br />Culex mosquito<br />Epizootic - nearly all birds and mammals become infected <br />Culex pipiens has preferential feeding for Turdus migratorius<br />Turdus migratorius<br />(Kilpatrick 2007)<br />
  8. 8. Transmission<br />Turdusmigratorius found responsible for ∼60% of WNV-infectious mosquitoes in several regions<br />The migration of Turdusmigratorius in the fall may cause greater mammalian and human infection<br />Culex mosquito<br />Turdus migratorius<br />(Kilpatrick 2007)<br />
  9. 9. Transmission<br />Many possibilities exist to explain transmission of West Nile virus across continents including:<br /> Alien species introduction<br />Culex incubation inside ships Transportation of incidentally infected organism Mutation allowing longer dormant viability<br />
  10. 10. Host competence is not limited to birds <br />(Kilpatrick 2007)<br />Demographics<br />The New York outbreak of killed great numbers of crows just before human infection <br />(Sfakianos 2005)<br />
  11. 11. Demographics<br />2008<br />1999<br />Multiple vectors, reservoirs, and hosts allowed West Nile to march all the way across the continental United States in less than a decade<br />
  12. 12. Factors associated with WNV Infection<br /> Immune response<br />Age (young and elderly)<br />Genetic factors <br />Unhealthy lifestyles<br />Viral replication<br />Rate of mutation<br />Initial viral infection count<br />Demographics<br />Tomas Aragon, MD, DrPHCenter for Infectious Disease PreparednessUC Berkeley School of Public Health<br />
  13. 13. Prevention<br />www.health.alberta.ca<br /> The new way to BBQ?<br />
  14. 14. Avoid high mosquito prevalent areas and times<br />Prevention<br />
  15. 15. Avoid high mosquito prevalent areas and times<br />Remove or properly treat standing water sources that encourage mosquito breeding<br />Prevention<br />
  16. 16. Avoid high mosquito prevalent areas and times<br />Remove or properly treat standing water sources that encourage mosquito breeding<br />Prevention<br />
  17. 17. Prevention<br />
  18. 18. Avoid high mosquito prevalent areas and times<br />Remove or properly treat standing water sources that encourage mosquito breeding<br />Wear proper insect repellent and clothing<br /> when participating in outdoor activities<br />Prevention<br />
  19. 19. Prevention<br />
  20. 20. Avoid high mosquito prevalent areas and times<br />Remove or properly treat standing water sources that encourage mosquito breeding<br />Wear proper insect repellent and clothing<br /> when participating in outdoor activities<br />Become vaccinated when available<br />Prevention<br />
  21. 21. Prevention<br />1 2 <br />3<br />4<br />
  22. 22. Prevention<br />3<br />4<br /> 5<br /> 6<br />
  23. 23. “Fun Facts”<br />Some people may be genetically predisposed to getting milder versions of the disease . (Sfakianos 2005)<br />WNV causes activation of both extrinsic and intrinsic apoptosis and it is currently theorized that inhibition of apoptosis may stop WNV from killing brain cells . (Kleinschmidt et. al. 2007)<br />Infection can happen a decade before <br /> disease is present. (Sfakianos 2005)<br />

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