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Jeremy Nathan
Flaviviridae family of viruses What is a virus? History and location of dengue fever Mosquito species vector Transmission and types of dengue fever Symptoms, treatment prevention
Most common mosquito borne disease in theworld
Global distribution is comparable to that of malaria 2.5 billion people live in high risk areas (CDC) 100 million cases of dengue fever and 500,000
cases of dengue hemorrhagic fever annually,several thousand deaths (Pandey 2008)
Epidemic in more than 100 countries(www.WHO.int)
Primarily spread through arthropod vectors(mosquitoes and ticks)
Flavivirus genus within this family Flavivirus genus contains West Nile, Dengue, and
Yellow Fever Flavivirus contains 67 known human/animal
viruses
First recorded outbreak in 1779-1780 in Asia,Africa and North Americasimultaneously.(CDC.gov)
Termed “Breakbone Fever” because of severepain in muscle and joints
Why simultaneously? Lurking undetected for at least 200 years before
first recorded (CDC.gov)
Tropical climates Regions near the equator Regions that support mosquitoes Areas that have man made water accessible to
mosquitoes for larvae Dense populations allow more rapid spread
Find Prey using senses of warmth, sight and smell Only females feed on blood Blood extracted via anti-coagulant in saliva Blood used for egg development
Mosquitoes carry dengue virus transmit it tohumans during feeding
Aedes aegypti acts as the main vector species ofmosquito
Vector is anything that carries and transmits virusbut doesn’t develop symptoms
No vaccinations currently available for DengueFever
Small structures containing DNA or RNA in proteincoat (Nowak 2004)
*Require a host Inject viral DNA and use machinery of host to
replicate (Nowak 2004) Stimulate an immune response (fever etc.)
Aedes bites an individual infected Virus is taken into stomach of mosquito Virus moves into salivary glands and replicates The infected Aedes then bites another individual and
injects virus containing saliva into host Virus enters the glands, continues replication, moves
into bloodstream Appearance of symptoms Dengue fever is NOT contagious
Four serotypes of Dengue Fever have beenrecognized according to the Center for DiseaseControl (CDC)
Serotype-closely related group of viruses that canbe differentiated based on the immune response
Den-1, Den-2, Den-3, and Den-4 are allantigenically different from one another
Dengue Hemorrhagic Fever(DHF) is more seriousand can result from dengue fever
Individual infected with dengue fever for the firsttime produces antibodies
Reexposure to dengue fever after recovery leadsto hemorrhagic fever
Immune system recognizes the virus and puts upstronger defense
More intense symptoms
Closely associated with humans (Thiruppathi2008)
Known to be the largest vector of Dengue Fever Day biter Lays eggs in manmade water holding vessels
(Thiruppathi 2008)
Following World War 2, Southeast Asia hit bydengue fever
Pandemic occurred in 1950’s By 1975, DHF had become a leading cause of
death in children (www.cdc.gov) Rio de Janeiro, Brazil 2002 1 million infected and 16 deaths
1950’s and 60’s insecticide DDT was used toaggressively eliminate Aedes aegypti (Phillips 2008)
Extremely successful 1970 DDT banned in US Other countries soon followed Reemergence of Aedes in North and South America
(Phillips 2008) "We have allowed Aedes aegypti to reinfest most if not
all of the urban areas of tropical America.“ (Phillips2008)
Impact of global warming
Figure 1: Reinfestation of Aedes aegypti in North and SouthAmerica after mosquito eradication program and in 2002.www.cdc.gov
1970 2002
Figure 2: Most recent distribution of dengue viruses from 2008.www.cdc.gov
Figure 3: Picture of dengue virus represented by black dots.www.cdc.gov
Exposure to any Dengue virus leads to immune response.Complex formed by antibody and virus allows for neutralization of virus.
Figure 4: Representation of antibodies formed by immunesystem in response to exposure to dengue virus.www.emerginginfections.slu.edu
High fever 3-14 days after bite Headache Muscle and joint pains (myalgia and arthralgia) Nausea Vomiting Rash *Many symptoms of dengue are flu like, so
misdiagnosis is a problemwww.cdc.com/denguehealthcarepractitioners
Figure 5: Illustration of symptoms of dengue fever.www.visualdxhealth.com
Same symptoms as dengue fever followed by: Skin hemorrhaging, bruising easily Bleeding of nose and gums/possible internal
bleeding Excessive permeability of capillaries If not treated, shock followed by death can result
Serological test for specific IgM IgG antibodies Isolation of virus from blood
Figure 6: Classic sign of dengue infection is the bloodleakage from eye capillaries. www.cdc.gov
Acetaminophen to reduce fever (avoid aspirin) Replenish Fluids Rest Continue monitoring blood pressure and
hematocrit levels after fever subsides
Wear clothing that cover your whole body Limit exposure to highly infested areas Use DEET spray as insect deterrent If you travel out of the country be aware your
surroundings
History of Dengue Where it is found Vector characteristics Types Immune response Symptoms, treatment and prevention
6 May 2009<http://www.cdc.gov/ncidod/dvbid/dengue/resources/DengueFactSheet.pdf> 7 May 2009 <http://www.who.int/csr/disease/dengue/en/> 6 May 2009 www.emerginginfections.slu.edu 10 May 2009 www.visualdxhealth.com/denguefeversymptoms Nowak, T. J. and A. G. Hanford. 2004. Essentials of Pathophysiology.
McGraw Hill Publishers Pandey, B. D., Morita, K. and S. R. Khanal. 2008. Dengue Virus, Nepal.
Emerging Infectious Diseases. 14(3): 514-515 Phillips, M. A. 2008. Dengue reborn. Environmental Health Perspectives.
116(9): 382-388 Thiruppathi, M. 2009. Dengue transmission. Environmental Health
Perspectives. 117(2): 56-57