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

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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://

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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


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)
subcutaneous hemorrhage on a dhf patient
Subcutaneous hemorrhage on a DHF patient

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
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)