Dengue is an acute febrile illness caused by one of four serotypes of the dengue virus transmitted by Aedes aegypti mosquitoes. Primary infection causes an IgM antibody response while secondary infection by a different serotype can cause severe dengue due to antibody-dependent enhancement. The disease progresses through three phases - febrile, critical, and recovery. The critical phase is characterized by increased vascular permeability leading to plasma leakage and potential development of shock. Diagnosis involves laboratory tests showing thrombocytopenia and hemoconcentration. Treatment is supportive and focuses on fluid management and antipyresis. Prevention relies on mosquito control and vaccine development.

1. DENGUE

2. Etiology
• Dengue is a acute febrile viral illness
• Caused by dengue virus with 4 serotypes 1, 2 , 3,
4
• Belongs to genus Flavivirus , family Flaviviridae
• Transmitted to humans by female Aedes aegypti
mosquito

3. Pathogenesis
• Dengue virus infects the mononuclear cells in
blood.
Two immune response
Primary
• No previous infection , 1st time infected
• IgM antibody response initially
• IgG antibody after 2 weeks

4. Secondary
• previously infected
• wide spread and rapid anamestic antibody
response
• IgG is dominant , IgM is low
• Once infected  life long immunity against the
same serotype but no protection against other
serotypes.

5. • But subsequent infection by another serotype
results in severe dengue
• 2nd infection  increases capacity to multiply
in monocytes  activation of CD4+ & CD8+
cytotoxic cells release of cytokines 
plasma leakage, disorder in hemostasis and
hemorrhage .

6. Pathophysiology
Two main pathophysiological changes in dengue
• increase in vascular permeability  loss of
pasma from vascular compartment 
hemoconcentration , low pulse pressure , shock
• Disorder in hemostasis  vascular changes ,
thrombocytopenia , coagulopathy

7. Clinical spectrum
• Traditionally dengue into 3 groups
 undifferentiated Dengue fever
 Dengue fever
 Dengue hemorrhagic fever (DHF)
Without shock with shock (DSS)
Dengue shock syndrome

8. WHO classification
Dengue fever
Without warning signs
Fever with any two
• Nausea, vomiting
• Rash
• Pain , aches
• Tourniquet test positive
• Leukopenia
• Lab confirmatory when no
signs of plasma leakage
with warning signs
• abdominal pain
• Persistent vomiting
• Clinical fluid accumulation
• Mucosal bleed
• Lethargy , restlessness
• Liver enlargement > 2 cm
Lab
• Increase HCT
• Decrease platelet count

9. severe dengue
Any one of the three
1)Severe plasma leakage –
• shock
• fluid accumulation with respiratory distress
2) Severe bleeding- evaluated clinically
3) Severe organ involvement
• Liver – AST or ALT > 1000 IU
• CNS – impaired consciousness
• CVS , Renal involvement

10. Clinical features
• Incubation period is 4-10 days
• Characterized by 3 distinct phases
Febrile phase
• High grade fever , fever is biphasic
• Myalgia ,bodyache , anorexia , nausea , vomiting,
headache
• Erythematous rash especially over extremities
• Artalgia ( break bone fever )
• Febrile phase lasts for 2-3 days

11. Dengue rash

12. Critical phase
• by 3rd day of illness ,Not all go to this phase
• Increase capillary permeability  plasma leak
into 3rd space  serosistis  ascitis , pleural
effusion
• Rise in hematocrit with falling platelet count
• Epigastrci pain , vomiting , hepatomegaly
• Mucosal bleed , petechiae
• Hypovolemia , hypoperfusion , shock
• Multi organ involvement , DIC
• Lasts for 48 hrs

13. Recovery phase
• Plasma reabsorption starts
• improvement in well being , appetite
• Urine output improves
• Pain abdomen subsides
• HCT nomalises
• Platelet count returns to normal
• Lasts for 48-72 hrs
• watch for hypervolemia

14. Lab studies
Raised HCT
• rise in HCT more than 20 % is sign of
hemoconcentration and precedes shock
Thrombocytopenia
• seen in 50% of cases
• Platelet less than 1 lakh – onset of critical phase
others leukopenia

15. • Prolonged PT , aPTT
• Low fibrinogen , elevated FDP  DIC
• Hyponatremia
• Metabolic acidosis
• Elevated urea
• Rise in AST , ALT

16. Serodiagnosis
• Detection of non structural protein ( NS1).
NS1 antigen is a highly conserved glycoprotein of
dengue virus secreted during initial illness.
• Detection of IgM antibodies to dengue
• Four fold rise in dengue IgG in paired samples
• Virus isolation by culture , genome detection by
PCR

17. Management
• No specific treatment
• Most important is supportive treatment
• Maintain Euvolemia , Euglycemia ,
Euthermia
• Use paracetamol as antipyretic not
other NSAIDS
• Management of SHOCK

18. Prevention & control
• Surveillance
• Vector control
• Biological and chemical control
• Vaccine development

19. THANK U