Microbiology presentation on West Nile Virus

1. By Linda Guzman

2. Preview of Main Points
• What it is?
• Its history
• Pathology – transmission
• Symptoms
• Preventative measures

3. What is the WNV?
• Flaviviridae family
• Icosahedral envelope – RNA
• 40-60 nm in size

4. WNV History
• 1937 – West Nile District of Uganda
• Africa, Middle East, Eastern Europe, West
Asia
• New York City 1999 – First case

5. WNV History
• 1999 – 62 cases and 7 deaths

6. WNV 2004

7. WNV 2011
• Every US state has reported a WNV case

8. WNV Global

9. Seasonal Disease
• Active during mosquito breeding season
• Spring till the end of August

10. Pathology
• Zoonotic
• Replicates in salivary glands
• Culex pipiens mosquito - the common house
mosquito

11. Transmission Cycle

12. Interesting Fact
• Europe – two types of Culex pipien population
• America – mosquito population has evolved
• Spread faster in America

13. Transmission
• Dead end host
• Per CDC – OK to
breast feed
• Infected mosquito
bites a human

14. Pathology
• Keratinocyte and dendritic
cell in basal layer
• Dendritic cells travels to
lymph nodes – 1st virus
replication
• Epithelial cells of visceral
organs – 2nd virus replication

15. Pathology
• Viremia triggers production of proteins &
enzymes
• Weaken tight junction of BBB

16. Pathology
• Neurons and glial cells infected
• Triggers cells narcosis = inflammation
• Encephalitis – inflammation of brain
• Meningitis – inflammation of meninges spinal cord

17. Who’s at Risk?
• Children, elderly,
compromised immune
system
• Over 50yo especially over
75yo – more at risk –
morbidity and mortality

18. Symptoms
• 3 to 14 days after infection
• 80% show no symptoms
• 20% show acute symptoms – mild, last couple of
days
– Fever, headache, body aches, nausea, vomiting, rash &
swollen lymph glands

19. Symptoms
• Out of 20% only 1% show
severe symptoms
– Tremors, stiff neck, high fever,
severe headache, paralysis,
muscle weakness, confusion,
convulsion, coma, encephalitis
or meningitis

20. Cure?
• There is not cure for WNV
• But there is one for horses
• Best way to protect is prevention

21. Prevention
• Stay indoors during dusk & dawn hours
• Long sleeves and long pants
• Insect repellent 10-30% DEET - mosquitoes
can still bite thru thin material

22. Prevention
• Dispose stagnant water

23. Works Cited
Byron E. E. Martina, et al. "West Nile Virus: Immunity and Pathogenesis." Viruses (1999-4915) 3.6
(2011): 811-828. Academic Search Complete. EBSCO. Web. 28 Sept. 2011.
Gerardi, Michael H., and Melvin C. Zimmerman. Wastewater Pathogens. John Wiley & Sons, Inc. (US),
2005. eBook Collection (EBSCOhost). EBSCO. Web. 28 Sept. 2011.
Hoyle, Brian. "West Nile." Infectious Diseases: In Context. Ed. Brenda Wilmoth Lerner and K. Lee Lerner.
Vol. 2. Detroit: Gale, 2008. 899-905. Gale Virtual Reference Library. Web.
Quick, Jennifer, and J. P. Saleeby. "The Mighty Mosquito-borne Killer." American Fitness 25.4 (2007):
26-29. Health Source - Consumer Edition. EBSCO. Web. 29 Sept. 2011.
"West Nile Virus." CRS - Pediatric Advisor (2010): 1. Health Source - Consumer Edition. EBSCO. Web. 29
Sept. 2011.