1 / 24

DENGUE FEVER

DENGUE FEVER. IRAM FATIMA. Dengue Fever. Dengue virus Most prevalent vector-borne viral illness in the world Main mosquito vector is Aedes aegypti Year round transmission. Incidence. 50-100 million dengue fever infections per year globally

audra
Download Presentation

DENGUE FEVER

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. DENGUE FEVER IRAM FATIMA

  2. Dengue Fever • Dengue virus • Most prevalent vector-borne viral illness in the world • Main mosquito vector is Aedes aegypti • Year round transmission

  3. Incidence • 50-100 million dengue fever infections per year globally • 500,000 cases of severe dengue, dengue hemorrhagic fever or dengue shock syndrome • 100-200 cases annually in U.S. • Average case fatality 5% • IN 2011 in pakistan 12000 cases and 165 deaths,,cases reported

  4. Distribution • Endemic in more than 100 tropical and subtropical countries • Pandemic began in Southeast Asia after WW II with subsequent global spread • Several epidemics since 1980s • Distribution is comparable to malaria

  5. Virology • Flavivirus family • Small enveloped viruses containing single stranded positive RNA • Four distinct viral serotypes (Den-1, Den-2, Den-3, Den-4)

  6. Pathophysiology • Transmitted by the bite of Aedes mosquito (Aedes aegypti) • Incubation 3-14 days • Acute illness and viremia 3-7 days • Recovery or progression to leakage phase

  7. Pathophysiology • Dengue virus enters and replicates within monocytes, mast cells, fibroblasts • Innate and adaptive immune response • Cytokine release: TNF-a, IL-2, IL-6, IL-8 • Compliment activation • T-cell activation: CD4 and CD8 cells cytokine production

  8. Pathophysiology Capillary Leak Syndrome: • Transient increased capillary permeability due to endothelial cell dysfunction • Widening of tight junctions • Cytokine release and complement activation Leukopenia, Thrombocytopenia and Hemorrhagic diathesis: • Direct viral bone marrow suppression • Platelet destruction in DHF • ?Molecular mimicry between viral protein and coagulation factors

  9. Clinical Presentation • Spectrum of illness • non-specific febrile illness • classic dengue • dengue hemorrhagic fever • dengue shock syndrome • other (CNS dysfunction, liver failure, myocarditis)

  10. Classic Dengue • Acute febrile illness with headache, retro-orbital pain, myalgias, arthralgias • “Break-bone fever” • High fever 5-7 days • Second fever for 1-2 days in 5% patients • Followed by marked fatigue days to weeks • Classic dengue 15-60% of infections • Nausea, vomiting, diarrhea (30%) • Macular or maculopapular confluent rash (50%) • Respiratory symptoms: cough, sore throat (30%)

  11. Dengue Hemorrhagic Fever • Usually occurs in secondary infections after actively or passively (maternal) acquired immunity to a different viral serotype • Only 2-4% of secondary infections result in severe disease • Mortality is 10-20% if untreated, but decreases to <1% if adequately treated • Plasma leakage may progress to dengue shock syndrome

  12. Dengue Hemorrhagic Fever WHO classification of DHF • Thrombocytopenia (platelet count <100,000) • Fever 2-7 days • Hemorrhagic manifestations with a positive tourniquet test, petechiae, ecchymoses or mucosal bleeding. • Hemoconcentration or evidence of plasma leakage (ascites, effusion, decreased albumin)

  13. Physical Exam • Nonspecific findings • Conjunctival infection, pharyngeal erythema, lymphadenopathy, hepatomegaly (20-50%) • Macular or maculopapular rash (50%)

  14. Laboratory Findings • Leukopenia • Thrombocytopenia (<100,000) • Modest liver enzyme elevation (2-5x nml) • Serology: • Acute phase serum IgM (+6-90 days) ELISA • Acute and convalescent IgG (99% sens, 96% spec) • Hemagglutination inhibition assay (HI) is gold assay, positive if >4

  15. Disease Factors • Dengue-2 serotype most virulent • Increased severity with secondary infections • Increased risk in children <15 years and elderly. • Greatest risk of DHF in infants. • More severe in females • Increased mortality with comorbid conditions • Less common in malnourished children

  16. Differential Diagnosis Viral: Influenza, HIV, Hepatitis A, Yellow Fever, Hantavirus, Measles, Rubella, Coxsackie and other enteroviruses, parvovirus B19, Chikungunya virus, EBV Bacterial: Typhoid, Scarlet fever, Meningococcemia Parasitic:Malaria, Leptospirosis, Rickettsial disease, Leishmaniasis, Chagas disease Fungal: Cryptococcus, Blastomycosis, Histoplasmosis Non-Infectious: Malignancy, rheumatic, vasculitis, drug fever, other miscellaneous

  17. Treatment • No specific therapy • Supportive measures: adequate hydration acetaminophen (if no liver dysfunction) avoid ASA and NSAIDs • DHF or DHF w/ shock: IV fluid resuscitation and hospitalization blood or platelet transfusion as needed

  18. Treatment • Treatment with corticosteroids shown not to reduce mortality with severe dengue shock • Ribavirin very weak in vitro and in vivo activity against flaviviruses

  19. Vaccination • No current dengue vaccine • Estimated availability in 5-10 years • Vaccine development is problematic as the vaccine must provide immunity to all 4 serotypes • Lack of dengue animal model • Live attenuated tetravalent vaccines under phase 2 trials • New approaches include infectious clone DNA and naked DNA vaccines

  20. Prevention Biological: • Target larval stage of Aedes in large water storage containers Chemical: • Insecticide treatment of water containers • Space spraying (thermal fogs)

  21. Prevention • Personal: • clothing to reduce exposed skin • insect repellent especially in early morning, late afternoon. Bed netting is of little utility. • Environmental: • reduced vector breeding sites • solid waste management • public education

More Related