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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
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)
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)
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)
Incidence
 West Nile Virus infections have been
reported in 48 States as of Dec. 2012 (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 neuroinvasive infections (meningitis or
encephalitis) and 49% of cases (2,653)
classified as non-neuroinvasive infections.
(Centers for Disease Control and Prevention, 2012)
West Nile Virus Activity in the US - 2012
Reported by ArboNET (Centers for Disease Control and Prevention
(2012).
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)
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)
West Nile Virus cases in
Georgia – 2012
(CDC, 2013)
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)
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
Death
(with or
without
associated
meningitis)
2002
49
46
64
78
2003
45
46
62
80
(Centers for Disease Control and Prevention, 2012)
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)
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)
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)
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)
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 antiinflammatory medications can be used.
 No Vaccine is available, and no antibiotics
are available for infection with WNV.
(MedicineNet.com, 2012)
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)
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)
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
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.)
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.)
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)




Effects of current controls on the
environment
Many communities use mosquito
management strategies that are ineffective
due to lack of information.
Pesticides used include organophosphates 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)
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)
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)
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)
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)
Recommendations to help reduce the
risk of infection and outbreaks
 Continued monitoring of birds, especially
dead birds.
Proposed Stakeholders
 Georgia Dept of Education.
 Georgia Dept of Public Health
 Community leaders in the State of Georgia
Sources for further reading

The Nemours Foundation. (2013). What's West Nile virus? Retrieved from:
http://kidshealth.org/kid/ill_injure/aches/west_nile.html

Campbell, G., Marfin, A., Lanciotti, R., & Gubler, D. (2002). West Nile Virus. THE
LANCET Infectious Diseases, 2: 519-529. Available at:
http://www.idready.org/courses/LancetInfectDis2002v2p519-Campbell.pdf

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: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640881/

Rossi, S. L., Ross, T., & Evans, J. (2010). West Nile Virus. Clinics in Laboratory
Medicine, 30(1): 47-65.

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, 2000. Emerging Infectious Diseases, 7(4): 654–658.
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:
http://www.cdc.gov/ncidod/dvbid/westnile/city_states.htm. Available at wnvguidelines-aug-2003.PDF

Centers for Disease Control and Prevention. (2012, December). West Nile
Virus: Statistics, Surveillance, and Control. Retrieved from:
http://www.cdc.gov/ncidod/dvbid/westnile/Mapsactivity/surv&control12Maps
AnybyState.htm

Centers for Disease Control and Prevention. (2012, December). 2012 West
Nile virus update: December 11, 2012. Retrieved from:
http://www.cdc.gov/ncidod/dvbid/westnile/index.htm
References

Centers for Disease Control and Prevention. (2012, September). West Nile
Virus: Epidemiologic Information for Clinicians: Risk Factors. Retrieved
from:
http://www.cdc.gov/ncidod/dvbid/westnile/clinicians/epi.htm#riskfactors

Centers for Disease Control and Prevention. (2012, September). West Nile
Virus: What You Need To Know. Retrieved from:
http://www.cdc.gov/ncidod/dvbid/westnile/wnv_factsheet.htm

Centers for Disease Control and Prevention. (2013, January). West Nile
Virus: Cumulative 2012 Data. Retrieved from :
http://diseasemaps.usgs.gov/wnv_ga_human.html

Georgia Department of Agriculture. (n.d.). West Nile Virus Questions and
Answers. Atlanta: Georgia Department of Agriculture.
References

Georgia Department of Public Health. (2013). Vector-borne Diseases.
Retrieved from: http://health.state.ga.us/epi/vbd/index.asp

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: 2002-2004. 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: 689-696, DOI:
10.1016/j.arcmed.2005.03.041.

MedicineNet.com. (2012). West Nile Encephalitis. Retrieved from:
http://www.medicinenet.com/west_nile_encephalitis/page5.htm

National Center for Biotechnology Information. (2012). West Nile Virus:
Causes, incidence, and risk factors Retrieved from :
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004457/
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): 14-23.

Petersen, L. R., Marfin, A. A., & Gubler, D. J. (2003). West Nile Virus.
Journal of the American Medical Association, 290(4): 524-528.

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