DENGUE

By

SUMAN, DNB

Trainee,

RICH Hospital.

HEADINGS

INTRODUCTION

ETIOPATHOGENESIS

CLASSIFICATION

CLINICAL COURSE

MANAGEMENT

PREVENTION

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

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

VECTORS

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

CYCLE OF TRANSMISSION

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

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

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

VIDEO On Transmission & Pathogenesis

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

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

NEW CLASSIFICATION-WHO 2009

DENGUE(PROBABLE DENGUE or

DENGUE WITHOUT WARNING SIGNS)

DENGUE WITH WARNING SIGNS

SEVERE DENGUE

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

CLINICAL COURSE:3 PHASES

FEBRILE PHASELasts 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

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

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

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

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

MANAGEMENT

ASSESSMENT

DIAGNOSIS

PROPER MANAGEMENT

STEP I - HISTORY

EXAMINATION

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

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

DENGUE SPECIFIC TESTS

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

STEP III – PROPER MANAGEMENT

Proper categorization into groups

Proper monitoring

Proper IV fluid administration

Proper management of complications

GROUPS

MONITORING

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

GROUP B-MANAGEMENTThese 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

GROUP C-MANAGEMENTThese 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

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

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

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

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

NATURAL REMEDIES

REFERENCES