Case study dengue virus virology 516 fall 2007 milette mahinan suzi sanchez olayinka taiwo
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Case Study: Dengue Virus Virology 516 Fall 2007 Milette Mahinan, Suzi Sanchez, Olayinka Taiwo. Dengue Virus Morphology. Dengue virus is a small, spherical,single stranded enveloped RNA virus Belongs to the family Flaviviridae. Http://news.uns.purdue.edu/html4ever/030618.Rossmann.immature.html.

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Case Study: Dengue Virus Virology 516 Fall 2007 Milette Mahinan, Suzi Sanchez, Olayinka Taiwo

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Case study dengue virus virology 516 fall 2007 milette mahinan suzi sanchez olayinka taiwo

Case Study: Dengue VirusVirology 516Fall 2007Milette Mahinan, Suzi Sanchez, Olayinka Taiwo


Dengue virus morphology

Dengue Virus Morphology

  • Dengue virus is a small, spherical,single stranded enveloped RNA virus

  • Belongs to the family Flaviviridae

Http://news.uns.purdue.edu/html4ever/030618.Rossmann.immature.html


Case study information

Case Study Information

  • Victim: a 30 year old woman

  • Symptoms: fever, backache, headache, myalgias in the upper arms, pain on moving her eyes, blanching erythematous rash on face, arms, trunk, and thighs,

  • Possible exposure area: had returned home from trip to El Salvador where she had extensive exposure to mosquitoes

  • Other physical characteristics: no enanthem, murmur, of splenomegaly

  • White blood cell count 1600/µl with a normal differential

  • Platlet count 140,000/µl

  • Hemoglobin 17.5g/dl

  • Convalescent phase antibodies tested positive for dengue virus


By what type of mosquito is this virus transmitted

By what type of mosquito is this virus transmitted?

  • Aedes aegypti mosquito

    • Small in comparison to other mosquitoes

    • Found in the tropics (dengue is the second most frequent cause of hospitalization among travelers returning from the tropics)

    • Some presence in the lower half of Florida


Dengue hemorrhagic fever dhf

Dengue Hemorrhagic Fever (DHF)

  • Dengue may appear as a severe and fatal disease called DHF.

  • DHF is defined by 4 criteria according to the world health organization:

  • 1) fever or history of fever lasting 2-7 days

  • 2) a hemorrhagic tendency shown by a positive tourniquet test or spontaneous bleeding

  • 3) thrombocytopenia (platelet count <100x109cells/L)

  • 4) evidence of plasma leakage shown by hemoconcentration with substantial changes in serial measurements, or by packed cell volume

  • Note: hemorrhagic manifestations without capillary leakage do not constitute DHF

  • Wilder-Smith, Ananth Tambyah (2007)


Other clinical manifestations

Other clinical Manifestations

  • Petichial rash on extremities such as, the forehead

  • the capillaries become excessively permeable, may lead to plasma leakage

  • Shock- due to rapid and weak pulse, may lead to DSS

  • Hapatomegaly (enlargement of the liver)- observed mostly in children living in Thailand.

  • In severe cases, circulatory failure, which if left untreated can result in death within 12-24hrs

  • nevertheless, people can recover following appropriate volume replacement therapy of the circulating fluid in the body


Dengue has 4 serotypes

Dengue has 4 serotypes

  • These are known as DEN-1,DEN-2,DEN-3, and DEN4

  • A viral serotype is distinguished by protein or a protein component that determines its antigenic specificity

  • Each viral serotype has characteristics that determine the nature of the epidemic and disease severity

  • Nisalak et al.(2003)


Secondary infection

Secondary Infection

  • It is common to see more serious symptoms related to secondary infection

  • Secondary infection occurs when a person is infected with a serotype distinct from the one that caused the initial infection

  • The predominant serotype causing an epidemic may vary by year and geographic location

  • DEN-1,2,3 are associated with moderately severe epidemic years

  • Only DEN-3 is associated with severe epidemic years

  • DEN-2,3 are associated with severe symptoms, DHF

  • Epidemics by multiple serotypes= hyperendemicity

  • Nisalak et al.(2003)

  • http://en.wikipedia.org/wiki/Dengue_fever


Subcutaneous hemorrhage on a dhf patient

Subcutaneous hemorrhage on a DHF patient

http://www.med.sc.edu:85/mhunt/arbo.htm


Will primary infection confer immunity to other serotypes

Will primary infection confer immunity to other serotypes????

  • It is known that immunity to the same serotype is long lasting (refers to the serotype causing the initial infection)

  • Immunity to a second serotype is at best transient

  • Based on the current information, it can be predicted that immunity to one serotype does NOT confer immunity to others that exist, or new ones that may arise

  • Rothman(2007)


Dengue endemic regions

Dengue endemic regions

  • The disease is now endemic in more than 100 countries in:

    • Eastern Mediterranean

    • South-east Asia

    • Pacific Islands

    • Central and South America

    • Carribean

    • Africa

    • WHO currently estimates that there may be 50 million cases of dengue infection worldwide every year

    • http://www.who.int/mediacentre/factsheets/fs117/en/


Preventive measures for travelers

Preventive measures for travelers

  • Use mosquito repellents containing DEET

  • Use mosquito nets

  • Insecticides

  • Wear protective clothing

  • Avoid being outdoors during the early morning and late afternoon (feeding times of the Aedes aegypti mosquitoes)


Thank you

Thank You!!!!!


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