Dengue Fever


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dengue fever in cebu city, philippines

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Dengue Fever

  2. 2. Dengue Fever/Dengue Hemorrhagic Fever <ul><li>4 serotypes (1-4) </li></ul><ul><li>Dengue virus- enveloped RNA arbovirus, Family Flaviviridae </li></ul><ul><li>Aedes aegypti – day biting female mosquito </li></ul><ul><li>Incubation period: 4-6 days </li></ul>
  3. 4. <ul><li>Dengue Fever: </li></ul><ul><li>Is a benign syndrome caused by several arthropod-borne viruses </li></ul><ul><li>Char: biphasic fever, myalgia/arthralgia, rash, leukopenia and LAD </li></ul>
  4. 5. <ul><li>Dengue Hemorrhagic Fever: </li></ul><ul><li>Severe, fatal, febrile disease </li></ul><ul><li>Char: capillary permeability, abnormalities of hemostasis, and severe – protein-losing shock syndrome(DSS) </li></ul>
  5. 6. <ul><li>WHO Criteria for diagnosis of DHF : </li></ul><ul><li>Fever </li></ul><ul><li>Major/minor hemorrhagic manifestations </li></ul><ul><li>Thrombocytopenia (<=100,000) </li></ul><ul><li>Objective evidence of capillary permeability( inc HCT =20%, pleural effusion, hypoalbuminemia) </li></ul>
  6. 7. <ul><li>Dengue Shock Syndrome: </li></ul><ul><li>DHF + </li></ul><ul><li>Hypotension </li></ul><ul><li>Narrow pulse pressure (=20 mmHg) </li></ul>
  7. 8. Pathogenesis of DHF: <ul><li>Increase capillary fragility- immune- complex rxn similar to anaphylactoid rxn that produce toxic substances (histamines, serotonin, bradykinins) which damage capillary walls </li></ul><ul><li>Thrombocytopenia -faulty maturation of megakaryocytes – dec production of plt </li></ul><ul><ul><li>Consumption of plt due to generalized intravascular clotting </li></ul></ul>
  8. 9. Pathogenesis of DHF: <ul><li>Dec blood coagulation factor(fibrinogen) and Factors II,V,VII,and IX. </li></ul>
  9. 10. Hypothesis that explain why DHF occurs in some individuals: <ul><li>Changes in virulence in some serotypes </li></ul><ul><li>Virus interaction with environment/ infectious agent </li></ul><ul><li>Differences in genetic susceptibility/ host factors </li></ul><ul><li>Immunologic enhancement of dengue infection by antibody acquired from previous infections with different dengue serotype. </li></ul>
  10. 11. Antibody –dependent enhancement of infection: <ul><li>most popular </li></ul><ul><li>Person who develop antibody from 1 st infection fail to neutralize a 2 nd dengue viral infection and even enhance the entry of virus to monocytes and macrophages – inc viral load and larger # of infected cells </li></ul>
  11. 12. Clinical manifestations: <ul><li>Maculopapular rash (Herman’s rash)- 5 th to 7 th day of illness </li></ul><ul><li>Fever (39-40C), acute in onset </li></ul><ul><li>Headache, periorbital pain, joint pains, and rash </li></ul><ul><li>Patient is flushed and acutely ill </li></ul><ul><li>Conjunctival injection </li></ul>
  12. 13. <ul><li>Anorexia, vomiting with abdominal pain </li></ul><ul><li>Temperature- biphasic </li></ul><ul><li>2 ND / 3 RD DAY – hyperpyrexia persists </li></ul><ul><li>Palms and soles are flushed </li></ul><ul><li>torniquet test often (+) </li></ul><ul><li>Petechiae seen in pressure areas </li></ul><ul><li>5 th – 7 th day – Herman’s Rash w/c last for 2-3 days </li></ul>
  13. 14. Stages : <ul><li>Febrile Stage ( 1-4 days ) </li></ul><ul><ul><li>Sudden onset of fever & Headache </li></ul></ul><ul><ul><li>Flushed skin </li></ul></ul><ul><ul><li>Anorexia, vomiting, abdominal pain </li></ul></ul><ul><ul><li>Hepatomegaly </li></ul></ul><ul><ul><li>Petechial observed in pressure areas ( tourniquet test ) </li></ul></ul>
  14. 15. <ul><li>Afebrile Stage ( 5- 7 days ) </li></ul><ul><ul><li>Lethargy </li></ul></ul><ul><ul><li>More sever abdominal pain </li></ul></ul><ul><ul><li>Restlessness </li></ul></ul><ul><ul><li>Hemorrhagic manifestation ( epistaxis, gum bleeding ) </li></ul></ul>
  15. 16. <ul><li>Convalescent Stage </li></ul><ul><ul><li>Improvement of appetite </li></ul></ul><ul><ul><li>Petechial rash </li></ul></ul><ul><ul><ul><li>Herman’s rash </li></ul></ul></ul><ul><ul><ul><li>Good prognostic sign </li></ul></ul></ul><ul><ul><ul><li>Glove & Stocking’s rash </li></ul></ul></ul><ul><ul><ul><li>Pruritic </li></ul></ul></ul>
  16. 17. Grading of DHF acc to severity: <ul><li>Grade 1: fever, non-specific symptoms, (+) torniquet test </li></ul><ul><li>Grade 2: grade 1 + spontaneous bleeding </li></ul><ul><li>Grade 3: grade 1 &2 + circulatory failure (rapid weak pulses, narrow pulse pressure 20 or less), hypotension, cold clammy skin and restlessness </li></ul><ul><li>Grade 4: profound shock </li></ul>
  17. 18. Tourniquet test procedure <ul><ul><li>Get blood pressure properly by covering 2/3 of arm with cuff </li></ul></ul><ul><ul><li>Get the mean blood pressure : </li></ul></ul><ul><ul><li>Mean blood pressure = systole + diastole / 2 </li></ul></ul><ul><ul><li>Maintain for 5-10 minutes at mean blood pressure </li></ul></ul><ul><ul><li>Check for petechiae using a 1x1 inch opening on a cardboard </li></ul></ul><ul><ul><li>A positive tourniquet test means at least 20 Petechiae per square inch </li></ul></ul>
  18. 19. Clinical Criteria of DHF: <ul><li>Fever w/ acute onset, high continuous, lasting 2-7 days </li></ul><ul><li>(+) toniquet test and any of petechiae, purpura, ecchymosis, gum bleeding and epistaxis </li></ul><ul><li>Hepatomegaly </li></ul><ul><li>shock </li></ul>
  19. 20. Laboratory criteria of DHF: <ul><li>Plt 100,000 or less </li></ul><ul><li>Hemoconcentration – hct increased by 20% or more </li></ul><ul><li>WBC in DHF is variable </li></ul>
  20. 21. <ul><li>Primary infection – no detectable antibody in acute phase serum samples collected on or before day 5 of illness </li></ul><ul><li>Secondary infection – antibody titer is detectable in the early acute phase serum </li></ul>
  21. 22. Treatment: <ul><li>DF: </li></ul><ul><ul><li>Supportive </li></ul></ul><ul><ul><li>Bedrest </li></ul></ul><ul><ul><li>Antipyretics/Analgesics </li></ul></ul><ul><ul><li>Aspirin is contraindicated </li></ul></ul><ul><ul><li>Fluid and electrolyte replacement of deficits by sweating, fasting, thirsting, vomiting and diarrhea. </li></ul></ul>
  22. 23. <ul><li>DHF: </li></ul><ul><ul><li>Immediate evaluation of vital signs and degrees of hemoconcentration, dehydration and electrolyte imbalance. </li></ul></ul><ul><ul><li>Close monitoring is essential for at least 48 hr because shock may occur or recur precipitously early in the disease. </li></ul></ul>
  23. 24. <ul><li>Oxygen– cyanotic/labored breathing </li></ul><ul><li>Rapid IV replacement of fluids and electrolytes can sustain patients until spontaneous recovery occurs. </li></ul><ul><li>Avoid overhydration- contribute to cardiac failure. </li></ul><ul><li>Transfusions of fresh blood or platelets suspended in plasma– control bleeding </li></ul>
  24. 25. Prognosis <ul><li>DF- adversely affected by passively acquired antibody or by prior infection with a closely related virus that predisposes to development of dengue hemorrhagic fever. </li></ul>
  25. 26. <ul><li>DHF-death has occurred in 40-50% of patients with shock </li></ul><ul><ul><ul><li>Survival is directly related to early and intense supportive treatment </li></ul></ul></ul><ul><ul><ul><li>Residual brain damage caused by prolonged shock or by intracranial hemorrhage. </li></ul></ul></ul>
  26. 27. Criteria for discharge <ul><li>Absence of fever for 46 hours </li></ul><ul><li>Return of appetite </li></ul><ul><li>Visible clinical improvement </li></ul><ul><li>Good urine output </li></ul><ul><li>Stable hematocrit </li></ul><ul><li>Recovery from shock </li></ul><ul><li>Platelet count of 150,000 </li></ul>
  27. 28. Prevention <ul><li>Avoiding mosquito bites by use of insecticides, repellants, body covering with clothing, screening of houses </li></ul><ul><li>Elimination of A. aegypti breeding sites </li></ul><ul><li>Insecticides/Larvicide </li></ul><ul><li>Fogging </li></ul><ul><li>Vaccine – Sabin-Schiessinger Vaccine (attenuated dengue virus) </li></ul>
  28. 29. thank you