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