etiopathogenesis,clinical course,management and prevention

1. DENGUE
By
SUMAN, DNB
Trainee,

2. HEADINGS
 INTRODUCTION
 ETIOPATHOGENESIS
 CLASSIFICATION
 CLINICAL COURSE
 MANAGEMENT
 PREVENTION

3. INTRODUCTION
 ARBOVIRAL INFECTION
 4 Closely related but antigenically different
serotypes-DEN1,DEN2,DEN3,DEN4
 DEN1 & DEN2 were prevalent until 1980’s
 DEN3-Recent outbreaks
 DEN4-Secondary dengue infections
 GENUS-Flavivirus
 FAMILY-Flaviviridae

4. VIRAL GENOME
 3 Structural proteins : C-Capsid
M-Membrane GP
E-Envelope
 7 Nonstructural proteins :
NS1,NS2a,NS2b,NS3,NS4a,NS4b,NS5
 NS1-Only NS protein which is soluble and
can be detected in circulation

5. VECTORS

6. VECTORS
Also serve to amplify viral replication
Feed on humans during daylight hours
Very anxious feeders
Often feed on several persons during a
single blood meal

7. CYCLE OF TRANSMISSION

8. PATHOPHYSIOLOGY
First infection in a dengue virgin body
produces a self limiting febrile illness
Exception in infants-Any presentation
First infection-immune response
Epitopes of E proteins are capable of
inducing antibody production in host
HOMOLOGOUS AB-Provides lifelong
immunity to that serotype

9. PATHOPHYSIOLOGY-Cont’d
 HETEROLOGOUS AB’s :
1)Neutralizing-Protects against other serotypes
for few months
2)Non-neutralizing-Forms complexes with other
dengue virus serotypes and causes enhanced
cellular infection
 ADE-Antibody Dependent Enhancement

10. PATHOPHYSIOLOGY-Cont’d
 Main mechanism-Transient increase in
vascular permeability
1) Leakage of fluid from intravascular to
interstitial and to serous cavities
2) Hemoconcentration-Increased Hct
3) Hypovolemia Hypotension Shock
Death

11. VIDEO On Transmission & Pathogenesis

12. CLASSIFICATION-OLD
DF-Mild self limiting febrile illness
DHF-Fatal with leaky vasculopathy
GRADE 1-Thrombocytopenia+Hemoconcentration
+ Positive TT + No spontaneous bleeding
GRADE 2-GRADE 1 + Spontaneous bleeding
GRADE 3-GRADE 2 + Circulatory insufficiency
GRADE 4-GRADE 3 + Imperceptible pulse & BP
DSS – GRADE 3 + GRADE 4

13. DRAWBACKS
Much overlap of symptoms
Undue emphasis on hemorrhage
Not included severe dengue disease
Non dengue febrile illnesses also show
positive tourniquet test
Managing patients based on this
classification is not appropriate

14. NEW CLASSIFICATION-WHO 2009
DENGUE(PROBABLE DENGUE or
DENGUE WITHOUT WARNING SIGNS)
DENGUE WITH WARNING SIGNS
SEVERE DENGUE

16. TOURNIQUET TEST
 AKA Rumpel-Leede capillary
fragility test
 Inflate BP cuff to midway b/w
systolic & diastolic pressures
for 5 minutes
 POSITIVE if ≥10 petechiae per
square inch
 DEFINITIVE FOR DENGUE if
≥20 petechiae per square inch

17. CLINICAL COURSE:3 PHASES

18. FEBRILE PHASE
 Lasts for 2-7 days
 Sudden onset of high grade fever
 Suffused & swollen face (Measly look)
 Injected eyes & Bloachable erythematous flush
 Maculopapular exanthem
 Positive TT-High probability of dengue
 Most neurological events occur due to direct
viral invasion of the brain(d/t viremia)
 Majority of patients have a smooth recovery

20. FEBRILE PHASE IN OLDER CHILDREN
 Headache
 Photophobia & Retro-orbital pain
 Anorexia , Nausea and Vomiting
 Myalgia , Arthralgia and Backache
 Bleeding tendencies
 Massive GI bleeding which is more common in
adults is rare in children
 LAB-Leucopenia , atypical lymphocytosis and
mild thrombocytopenia

22. CRITICAL PHASE
 Includes dengue with warning signs and severe
dengue
 Starts with the onset of plasma leakage
 Needs regular monitoring and prompt fluid
therapy to improve outcome of patient
 Scanty urine & Postural hypotension
 SHOCK noticed by Cold & clammy peripheries ,
Feeble pulse ,prolonged CRT ,Narrow PP ,
Decrease in SBP
 RESPIRATORY DISTRESS - PE & ASCITES

23. CRITICAL PHASE-Cont’d
 PROFUSE BLEEDING - Multi factorial(Shock
leading to HYPOXIA & ACIDOSIS ,
Thrombocytopenia, Coagulopathy ie DIC)
 Sudden fall in otherwise elevated Hct should
alert clinician for occult internal bleeding
 HEPATITIS - AST>ALT(>1000 IU)
 MYOCARDITIS – Hypokinesia ,Low EF
 ENCEPHALITIS – Convulsions ,Unconsciousness

24. RECOVERY PHASE
 Good appetite ,clinically improved condition
 Passing copious amount of dilute urine
 Bounding pulse ,Wide PP ,Rise in BP
 Hemoconcentration resolves & platelets rise
 Development of bright red confluent petechial
rash esp in acral regions
 In some annular petechial rash(isles of white in
a sea of red)
 Effusions are slow to resolve and may take few
more days for complete clearance

27. MANAGEMENT
ASSESSMENT
DIAGNOSIS
PROPER
MANAGEMENT

29. STEP I - HISTORY

30. EXAMINATION

31. INVESTIGATION
 COMPLETE BLOOD PICTURE
 Hct in early febrile phase-Baseline value
 Decreasing WBC-Dengue very likely
 Increasing LYMPHOCYTES-d/t Immune response
 Decreasing PC with parallel rise in Hct compared to the
baseline suggests progression to critical phase
 THROMBOCYTOPENIA is d/t Molecular mimicry : AB’s
against dengue virus proteins(esp NS1),cross react with
platelet surface proteins

32. OTHERS
CXR/USG CHEST-Shows varying degree
of Pleural effusion
USG ABDOMEN-Shows Ascites and
Edematous gall bladder
ADDITIONAL TESTS(If indicated as per
clinical condition) include Blood sugar,
Serum electrolytes, LFT, KFT,
Bicarbonate & Lactate levels etc

33. DENGUE SPECIFIC TESTS

36. Is it dengue?
If so which phase is it in?
Any warning signs?
Hydration status
Haemodynamic status
Admission criteria
Categorise into groups for proper
management
STEP II-DIAGNOSIS

39. STEP III – PROPER MANAGEMENT
Proper categorization into groups
Proper monitoring
Proper IV fluid administration
Proper management of complications

40. GROUPS

41. MONITORING

42. GROUP A-ADVICE
Adequate bed rest
Encourage the child to drink plenty of
fluids
Paracetamol/Tepid sponging for fever
Avoid other NSAID’s – may aggravate
gastritis or bleeding
Immediate return to hospital if
development of any warning signs

43. GROUP B-MANAGEMENT
These are the patients with plasma leak
Obtain reference Hct before fluid therapy
Administer IV fluids preferably crystalloids
that are isotonic for 24-48 hrs
0.9% Nacl or Ringer’s lactate
Frequently monitor vitals and Hct and
administer fluid accordingly
Fluid is discontinued when vitals & Hct are
stable and the child passes adequate urine

45. GROUP C-MANAGEMENT
 These are the patients with shock(sev dengue)
 Establish 2 IV lines if possible
 Obtain reference Hct before fluid therapy
 Includes FLUID RESUSCITATION and FLUID
REPLACEMENT
 Judicious IVF RESUSCITATION is the essential
and usually the sole intervention required
 Further plasma loses were rectified by
continuous IVF REPLACEMENT for 24-48 hrs

46. FLUID RESUSCITATION
 Strategy in which larger volumes of fluid(10-20
ml/kg boluses) are administered for a limited
period of time under close monitoring

47. RULE OF 20 IN DENGUE
Increase in PR by 20
Fall of BP by 20
Fall of PP(SBP-DBP) below 20
More than 20 petechial spots after a
tourniquet test
Needs 20 ml/kg fluid resuscitation

52. MANAGEMENT OF BLEEDING
 Bed rest to avoid trauma
 Avoid NSAID’s/IM Injections
 Give 5-10 ml/kg of fresh packed RBC (or)
Give 10-20 ml/kg of fresh whole blood
 Even if bleeding persists ,suspect DIC
 In DIC ,FFP and PRP may be considered
 NO ROLE of prophylactic Platelet therapy
 Consider platelets if count <10000/cubic mm
with bleeding manifestations

53. MANAGEMENT OF FLUID OVERLOAD
 Excess use of IVF & Inappropriate transfusion
of blood products results in fluid overload
 Presence of comorbid conditions like CHD ,
Renal failure ,Liver disease will aggravate
 STOP further FLUIDS
 Supply Oxygen to patients in resp distress
 Oral or IV furosemide 0.1-0.5 mg/kg/dose
once or twice daily
 Else continuous infusion @ 0.1mg/kg/hr

54. NATURAL REMEDIES

59. REFERENCES