1. Presented by Fathiya I. Hampton. January 2013
West Nile Virus in Georgia – Causes, incidence, prevention and control, effects of current controls on the environment, and recommendations for reduction of the risk of infection and outbreaks.
Presented by Fathiya I. Hampton.
January 2013

2. Causes of West Nile Virus
Spread by mosquitoes that bite infected birds, then bite humans.
Caused by a virus (flavivirus).
Highest amount of virus carried by mosquitoes during early fall season.
Many people infected with West Nile virus (WNV) do not know they have been infected.
(National Center for Biotechnology Information, 2012)

3. History of West Nile Virus
First discovered in the West Nile District of Uganda in 1937.
Ecology and epidemiology first characterized in early 1950s and 60s in the Mediterranean Basin.
First epidemic occurred in Israel in 1951 with 123 cases (mostly children) out of population of 303. No fatalities reported.
(Sejvar, 2003)

4. History – cont…
Extended study of West Nile Virus carried out in Egypt in 1951 after a large number of outbreaks.
Study results increased understanding of West Nile virus.
First detected in the US in New York in 1999 after an outbreak.
WNV spread to 10 other States in 2001 with increased equine cases and avian deaths.
(Sejvar, 2003)

5. Incidence
West Nile Virus infections have been reported in 48 States as of Dec (in people, mosquitoes and birds).
The number of cases reported to CDC totaled 5,387 (people) with 243 deaths.
51% of cases (2,734) classified as neuro-invasive infections (meningitis or encephalitis) and 49% of cases (2,653) classified as non-neuroinvasive infections.
(Centers for Disease Control and Prevention, 2012)

6. West Nile Virus Activity in the US - 2012
This map shows the activity or occurrence of West Nile Virus infections in the United States in Most of the infections occurred in the South of the US and the Northern parts. There was increased activity in the Northeastern parts of the US in MA, NY and other states around the area.
West Nile Virus Activity in the US
Reported by ArboNET (Centers for Disease Control and Prevention (2012).

7. Factors affecting distribution of West Nile Virus in Georgia
Distribution of WNV is dependent on existence of competent mosquito vectors and avian reservoir hosts.
Both can be influenced by geographic variables.
Factors affecting distribution of WNV in Georgia include: Mountain physiographic region, urban/suburban land use, housing density, and temperature.
(Gibbs, et al., 2006)

8. Factors affecting distribution of West Nile Virus in Georgia – cont..
Risks for WNL being endemic increase in urban and suburban areas and decrease in the mountainous region of Georgia.
Lower temperatures in the mountains of Georgia has resulted in decrease in abundance of mosquitoes.
(Gibbs, et al., 2006)

9. West Nile Virus cases in Georgia – 2012 (CDC, 2013)
Most of the West Nile Virus NBH cases occurred in the summer months between June and September. This is because the temperatures are high during summer, which is conducive to the reproduction of mosquitoes. People also spend more time outside during summer months, hence they are more susceptible to being bitten by mosquitoes.

10. Risk factors for West Nile Virus
Very young or older individuals.
Organ transplants.
Blood transfusions.
Pregnancy
Weaker immune system due to recent chemotherapy, organ transplant, or HIV.
(National Center for Biotechnology Information, 2012)

11. Risk factors for West Nile Virus – Cont…
Table of Median age (in years) of development of West Nile illness following infection
Year
Fever
Meningitis
Encephalitis (with or without associated meningitis)
Death
2002 49 46 64 78
2003 45 62 80
(Centers for Disease Control and Prevention, 2012)
Age is a risk factor for West Nile Virus. You will notice that in 2002 and 2003, the only deaths were in the age range of over 70 years.

12. Implications of Global warming on West Nile Virus
Researchers believe Global warming will cause changes in epidemiology of infectious disease such as West Nile Virus.
Effects of global warming include: changes to plant and animal populations, changes in global patterns of rainfall, failure of crops and famine, elevated sea levels, and serious effects on health.
(Khasnis & Nettleman, 2005)

13. Implications of Global warming on West Nile Virus –cont..
Global warming will affect the distribution and abundance of vector diseases.
Altitudes too cool to sustain mosquito vectors will be more conducive to them.
Vector populations could move to new geographic locations.
Lifespan of mosquitoes decreases with increased temperatures, but maturation of viruses increases with temperature.
(Khasnis & Nettleman, 2005)

14. Symptoms
Symptoms develop within 3-14 days after being bitten by infected mosquitoes.
Serious symptoms: One of every 150 infected individuals develops severe illness.
Symptoms include high fever, vision loss, muscle weakness, convulsions, tremors, coma, disorientation, stupor, neck stiffness, headache, numbness and paralysis.
(Centers for Disease Control and Prevention, 2012)

15. Symptoms
Milder symptoms: About 20% of infected individuals have milder symptoms.
Symptoms include: Nausea, body aches, headache, fever, skin rashes on back, chest, stomach; and swollen lymph glands.
No symptoms: Almost 80% of infected individuals show no symptoms of WNV.
(Centers for Disease Control and Prevention, 2012)

16. Treatment No specific treatment for WNV infections.
For complications of brain infections treatment includes intensive supportive therapy.
For severe cases intensive medical monitoring, intravenous fluids, and anti-inflammatory medications can be used.
No Vaccine is available, and no antibiotics are available for infection with WNV.
(MedicineNet.com, 2012)

17. Prevention and Control
Community based mosquito control programs that reduce vector populations.
1. Reduction of the Source of mosquitoes including water management and sanitation.
2. Personal protection measures to help reduce the risk of mosquito bites.
- Using mosquito repellents.
- Wearing long sleeved clothing outside.
(Centers for Disease Control and Prevention, 2012)

18. Prevention and Control
Chemical control. Chemicals must comply with federal and state requirements and are used in:
- Larviciding (killing mosquito larvae).
- Adulticiding (killing adult mosquitoes).
Resistance Management – used to prevent resistance of vectors to insecticides.
(Centers for Disease Control and Prevention, 2003)
(Centers for Disease Control and Prevention, 2003 )

19. Prevention and Control
Surveillance programs that characterize risk patterns which can be used to tailor intervention programs.
- Mosquito larva surveillance
- Adult mosquito surveillance
- Virus surveillance
(Centers for Disease Control and Prevention, 2012)
(Centers for Disease Control and Prevention, 2003 )
Surveillance of mosquito larvae consists of sampling of habitats for the presence of vectors during their developmental stages. Vector populations are identified and sprayed. Surveillance of adult mosquitoes is used to find out what species of mosquitoes are present as compared to mosquitoes in the area. This helps in monitoring vector activity in the area and developing interventions for control of the mosquitoes. Virus surveillance is mainly used to find out prevalence of West Nile Virus in the population of mosquitoes. This provides information for calculating the index of virus prevalence.

20. Common Misconceptions
Dead birds will make people sick – Not true. The WNV is spread from live birds to people when mosquitoes bite people.
WNV can affect the poultry industry in Georgia – Not likely. WNV is not significant in poultry, especially in Georgia, where they are housed indoors.
West Nile Virus can cause illness in cats and dogs – Very unlikely, especially cats.
(Georgia Department of Agriculture, n.d.)

21. Common Misconceptions – cont…
WNV will affect cattle – Not likely. WNV does not affect cattle.
Electric “bug zappers” can help control mosquitoes – Not true. These could attract more mosquitoes to the area, and kill other insects that are beneficial.
Taking Vitamin B or eating garlic will repel mosquitoes – Not true. There is no scientific evidence to back this up.
(Georgia Department of Agriculture, n.d.)

22. Current Interventions
Equine monitoring and surveillance to ensure that horses are not infected.
Human monitoring and surveillance to ensure that there will be no outbreaks.
Avian Surveillance – Monitoring and surveillance of bird populations, including sick and dead birds.
Georgia Dept. of public health’s notifiable disease section monitors vector borne diseases.
(Georgia Department of Public Health, 2013)

23. Effects of current controls on the environment
Many communities use mosquito management strategies that are ineffective due to lack of information.
Pesticides used include organo- phosphates and synthetic pyrethroids.
Spraying pesticides has been known to harm the environment.
Adulticides kill beneficial insects such as dragonflies, butterflies, and bees.
(National Coalition against the Misuse of Pesticides, 2002)

24. Effects of current controls on the environment – cont…
Spraying of pesticides can increase the number of mosquitoes in the environment as they become resistant to pesticides.
Pesticides also destroy the natural predators of mosquitoes.
Organic phosphates have been associated with cancer and birth defects in people.
(National Coalition against the Misuse of Pesticides, 2002)
(Howard & Oliver, 1997, as cited in National Coalition against the Misuse of Pesticides, 2002)

25. Recommendations to help reduce the risk of infection and outbreaks
Development of better ways to measure population of mosquitoes in certain areas.
This will enable public health officials to conduct adequate risk-benefit analysis of adulticiding.
Development of pesticide monitoring systems to accurately measure and record type and amount of pesticides, as well as location of spraying.
(National Coalition against the Misuse of Pesticides, 2002)

26. Recommendations to help reduce the risk of infection and outbreaks
Better training for mosquito control teams and applicators of pesticides for better safety and efficiency.
Using Adulticiding as a last resort and spraying responsibly.
Pesticides that are the least dangerous should be used, for example pyrethroids.
Use of DEET-based repellents for personal protection from mosquitoes.
(National Coalition against the Misuse of Pesticides, 2002)
(Centers for Disease Control and Prevention, 2003)

27. Recommendations to help reduce the risk of infection and outbreaks
Educating the public about personal protection, including using protective clothing, awareness of mosquito-biting behaviors, and the use of repellent.
Educating the public about protection in their homes, for example, use of screens on doors and windows, getting rid of breeding sites for mosquitoes.
Encourage reporting of dead birds.
(Centers for Disease Control and Prevention, 2003)

28. Recommendations to help reduce the risk of infection and outbreaks
Continued monitoring of birds, especially dead birds.

29. Proposed Stakeholders
Georgia Dept of Education.
Georgia Dept of Public Health
Community leaders in the State of Georgia

30. Sources for further reading
The Nemours Foundation. (2013). What's West Nile virus? Retrieved from:
Campbell, G., Marfin, A., Lanciotti, R., & Gubler, D. (2002). West Nile Virus. THE LANCET Infectious Diseases, 2: Available at:
Rappole, J. H., Derrickson, S. R., & Hubálek, Z. (2000). Migratory birds and spread of West Nile virus in the Western Hemisphere. Emerging Infectious Diseases, 6(4): 319–328. Available at:
Rossi, S. L., Ross, T., & Evans, J. (2010). West Nile Virus. Clinics in Laboratory Medicine, 30(1):
Weiss, D., Carr, D., Kellachan, J., Tan, C., Phillips, M., Bresnitz, E., & Layton, M. (2001). Clinical Findings of West Nile Virus Infection in Hospitalized Patients, New York and New Jersey, Emerging Infectious Diseases, 7(4): 654–658.

31. References:
Centers for Disease Control and Prevention. (2003). Epidemic/Epizootic West Nile Virus in the United States: Guidelines for Surveillance, Prevention and Control. Retrieved from: Available at wnv-guidelines-aug-2003.PDF
Centers for Disease Control and Prevention. (2012, December). West Nile Virus: Statistics, Surveillance, and Control. Retrieved from:
Centers for Disease Control and Prevention. (2012, December) West Nile virus update: December 11, Retrieved from:

32. References
Centers for Disease Control and Prevention. (2012, September). West Nile Virus: Epidemiologic Information for Clinicians: Risk Factors. Retrieved from:
Centers for Disease Control and Prevention. (2012, September). West Nile Virus: What You Need To Know. Retrieved from:
Centers for Disease Control and Prevention. (2013, January). West Nile Virus: Cumulative 2012 Data. Retrieved from :
Georgia Department of Agriculture. (n.d.). West Nile Virus Questions and Answers. Atlanta: Georgia Department of Agriculture.

33. References
Georgia Department of Public Health. (2013). Vector-borne Diseases. Retrieved from:
Gibbs, S., Wimberly, M., Madden, M., Masour, J., Yabsley, M., & Stallknecht, D. (2006). Factors affecting the geographic distribution of West Nile virus in Georgia, USA: Vector borne and zoonotic diseases, 6(1):73-82.
Khasnis, A. A., & Nettleman, M. D. (2005). Global Warming and Infectious Disease. Archives of Medical Research, 36: , DOI: /j.arcmed
MedicineNet.com. (2012). West Nile Encephalitis. Retrieved from:
National Center for Biotechnology Information. (2012). West Nile Virus: Causes, incidence, and risk factors Retrieved from :

34. References
National Coalition against the Misuse of Pesticides. (2002). Public Health Mosquito Management Strategy: Managing Mosquitoes and Insect borne diseases with Safety in mind. Pesticides and You, 22(2):
Petersen, L. R., Marfin, A. A., & Gubler, D. J. (2003). West Nile Virus. Journal of the American Medical Association, 290(4):
Sejvar, J. J. (2003). West Nile Virus: An Historical Overview. The Ochsner Journal, 5(3):6-10.
Fathiya I. Hampton
Walden University
Environmental Health - PUBH 8165
January 2013