DENGUE

FEVER

Amila Weerasinghe

MBBS Undergraduate2010/2011 Batch (21st )Faculty of Medical SciencesUniversity of Sri JayewardenepuraSri Lanka

19/01/2015

1. What is ‘’Dengue’’ ?

2. Epidemiology

3. Vector

4. Virus

5. Pathogenesis of the disease

6. Classification

7. The natural course of the illness

8. Diagnosis and Management at OPD level

and by primary care physician.

9. In-ward Management of DF/DHF

10. Management of complicated patients

Contents

A vector borne disease.

The most rapidly spreading mosquito-borne viral disease in the world.

A notificable disease in Sri Lanka

World situation

last 50 years, 30 fold rise

2.5 billion or 40% of the world, live in

dengue endemic countries.

WHO (2009).Dengue: guidelines for diagnosis, treatment, prevention and control -- New edition

Yearly 50 to 100 million infections

500,000 DHF cases

22,000 deaths, mostly among children.

Sri Lankan situation

First serologically confirmed case - 1962

First documented dengue outbreak -1965- 1966

First epidemic of DHF/ Dengue Shock Syndrome - 1989 – 1990.

2014 46584

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Cases

Year 2014, 46584 suspected dengue cases

55.26% of dengue cases from the Western province.

http://www.epid.gov.lkhttp://www.dengue.health.gov.lk

Vector

Host

(Human)

Virus

A biological vector – Mosquitoes In Sri Lanka Aedes albopictus and Aedes aegypti

Aedes aegypti is the main species.

Genus – Flavi virus

Family – Flaviviridae

Virus – Dengue virus (DEN)

Serotypes – 4 serotypes

DEN 1 to 4

Primary dengue infection

First time viral infection,

Any of the 4 virus types.

Secondary dengue infection

# Viral infection, except

which resulted the primary infection.

# NOT necessarily the ‘’second’’ dengue

infection.

Old WHO classification

WHO new classification

WHO new classification

Old WHO classification

2 – 7 days of illness + high grade feverHeadacheRetro – orbital painMyalgiaArthralgiaRash & haemorrhagic manifestations

positive tourniquet test

petechiae

Signs & symptoms +

Criteria

High fever/ recent history of acute fever

A (+)ve tourniquet test

Thrombocytopaenia <100,000 cells/mm3

Objective evidence of leaky capilaries•≥20% Elevated haematocrit•Pleural or other effusion - eg, ascites.•Low protein.

Dengue haemorrhagic fever is a

dynamic disease

1. Febrile phase

2. Critical phase

3. Convalescent phase

When to suspect DF/DHF

Management as out patients

Oral fluid (maintainance)

Eg:-oral rehydration fluid,king coconut juice, fruit juices….etc

Except plain water and red and brown drinks

Rest & tepid sponging

Paracetamol 10-15mg/kg/dose (max 60mg/kg/day)

Anti-emetics and H2 RB.

NO NSAIDs or any STEROID

Review with FBC , 1st after 3 days of onset

Advice to return immediately for

review…… if……

When to admit the patient ?

Clinical judgment

All patients with plt 100,000/mm3

All patients with warning signs

Following patients with probable dx of DF

should admit.

Infants

Obese

Major co-morbidities

Adverse social circumstances

Febrile Phase

Critical Phase

Convalescent

Phase

In DF & DHF ; lasts for 2-7 days

Total WBC count

initially high or normal drops < 5000/mm3

Platelet count

Initially normal drops < 100,000/mm3

in 50% DF & 100% DHF

Tender hepatomegaly DHF > DF

Erythematous/ maculo-papular rash DHF < DF

Adequate fluid intake

Total fluid requirement degree of dehydration(oral + IV)

Maintenance volume

Infants <6 months – 5% dextrose in N/2

Others – normal saline

Adequate physical rest

Paracetamol 10-15mg/kg/dose

(max 60mg/kg/day)

NO all NAIDSs & STEROIDS

Monitoring - ( Annexure iii) in the dengue

guideline

Seen only in DHF

late febrile phase;

3rd day to 7th day of illness up.

Rapid drop in temperature

Lasts for 24 – 48 hours

DHF is a very dynamic disease.

Identifying

the beginning & the end of the critical phase

is a KEY FACTOR

in guiding fluid therapy in DHF.

Leak starts slowly, increases gradually,

peak around 24 hours, slows down and

ceases around 48 hours.

0

5

10

15

20

25

30

0 20 40 60

.

Until the very last stage of shock; patient can

appear conscious & very alert

If Pulse Rate & Blood pressure NOT measured,

early shock could be missed.

Platelets <100,000/mm3

Be Alert

Patient may be in either of the,

DF(50% of patients)

DHF febrile phase

DHF critical phase (early or late)

1. 20% rise in the haematocrit

2. Objective evidence detected radiologically

Pleural effusion USS chest

Chest X-ray RightLateral decubitus

Ascites : USS abdomen

3. Biochemical parameters

Serum albumin < 3.5g/dl or dropped by 0.5g/dl

Serum cholesterol <100mg/dl or dropped by 20mg/dl

( NON fasting )

Calculation of the fluid quota (oral+IV)

Max fluid intake during ENTIRE critical phase [Irrespective of its length]

Maintenance + 5% deficit

Maintenance = 100ml/kg for 1st 10kg

+ 50ml/kg for next 10kg

+ 20ml/kg for the balance weight

5% deficit = 50ml/kg x body weight (kg)

Ideal body weight

Weight for height [ BEST ]Weight for age

BUT

Actual body weight is taken for the calculations,

if the actual weight < ideal weight

Growth chart –50th centile

Maximum weight = 50kg

Maximum fluid intake = 4600ml

IV fluids

N/2 +5% dextrose < 6 months infants

N saline + 5% dextrose > 6 months; who is not taking orally for prolonged

[ 50ml of 50% dextrose + 450ml N saline ]

A patient without shock

IV normal saline/ Hartmann’s solution –largest possible size for the age. + oral fluids

Initially; oral +IV = 1.5ml/kg/hr

Who can drink well = 0.5ml/kg/hr

Pulse, BP, Pulse pressure, CRFT,HCT &

UOP

UOP calculation

Hourly UOP ; Best guide for the rate of infusion

0.5-1.0ml/kg/hr sufficient

IF

UOP >1.0 – too high infusion rates

UOP <0.5 – inadequate fluids

A patient with shock

Symptoms

• Sweating

• Abdominal pain

• Restlessness

• Altered conscious level

Signs

• Cold extremities

• CRFT > 2 sec

• Unexplained tachycardia

• Increased DBP

• Narrowing pulse pressure 20mm/Hg

Mx of shock (if pulse & BP not picked up.)

After 2 crystalloid boluses;

Already having a fluid overload

The full fluid quota given.

ONLY during the critical phase

ONLY used as a bolus; Maximum over 1

hour.

(10ml/kg/hr)

Dextran 40 – up to 3 doses within 24 hrs(10ml/kg/hr)

6% Starch – up to 5 doses within 24 hrs(10ml/kg/hr)

Stable vital signs

HCT becomes normal

Clinically improvement

Diuresis

Lasts for 2-5 days

Reabsorption of the extravasated fluid.

ComplicationsFluid overloadHypocalaemiaNosocomial infections

No fever 24hrs, without antipyretics

At least 2 days after recovery from shock

Generally good & Increasing apetite

Normal HCT for age..

[baseline around 38-40% when not known]

No distress from pleural effusion or ascitis

Rising platelet count & >50,000/mm3

No other complication

Infants

Obese

Bleeding

Encephalopathy

Underline diseases

Pregnancy

Prolonged shock

>4 hrs organ failure

Liver failure 50% prognosis

Liver + Renal 10% prognosis

3 organs(+ respiratory) very bad

Fluid overload

Features :-

Early- puffy eye lids, distended abdomen

(ascites), tachypnoea, mild dyspnoea

Late – Respiratory distress, SOB, &

wheezing

A – acidosis

B – Bleeding

C – Calcium (hypocalcaemia)

S – Sugar (hypoglycaemia)

Acidosis

More prone to DIC & massive bleeding.

pH < 7.35 (Arterial normal 7.35-7.45)

HCO3- < 15 mmol/l (Arterial normal 22-24)

Emperically

NaHCO3 1ml/kg slow bolus (max 50ml)

Diluted in equal volume of Normal Saline

Bleeding

Ix for blood transfusion

Overt bleeding

Concealed bleeding

( HCT drop/metabolic acidosis)

Use Packed Red Cells

5ml/kg once

5ml/kg of PRC HCT by 5 points

(eg:- 30 to 35)

If HCT > 45%, blood given only after

reducing HCT by a colloid.

Hypocalcaemia

Mostly with ‘’convulsions’’Measure serum Ca2+ levels

Give calcium if complicated

1ml/kg of 10% Ca Gluconate,(max 10ml)Slow IV bolus over 15-20 minsDiluted in equal volume of NSRepeat 6 hourly

Hypoglycaemia

Prevented by NS with 5% Dextrose

•Dextrose saline (0.9% NaCl with 5%

Dextrose)

•Add 50ml 50% Dextrose to 450ml of

0.9% NaCl

Immediate goalplasma glucose at least 70mg/dl

10% dextrose, 2ml/kg by IV push

Continue IV dextrose rate at 8mg/kg/min

Hyponatraemia

Mainly due to Hyponatraemic fluids

N/2 NaCl, N/5 NaCl, Water

3% NaCl is 3-5ml/kg

Slow IV

Through a larger vein; mostly a central vein

Encephalopathy

Mainly - Hepatic encephalopathy

Maintain cerebral perfusion pressure(CPP)

Maintain - Mean arterial pressure (MAP)

Reduce – Intra Cranial pressure (ICP)

CPP = MAP - ICP

Airway oxygenation with O2 therapy

Fluid management

Maintain MAP

Reduce ICP

Maintain blood sugar level >70 mg/dl

Maintain K+ & Na+ levels normal3% NaCl if Na+ < 120meq/l

Vit K IV 3mg <1yr 5mg 1-5yrs, 10mg >5yrs

IV Phenobarbitone - cerebral metabolismControls seizures

Gut cleaning NG tubeAntibiotics – MetranidazoleLactulose

Platelet transfusionRecombinant factor vii InotropsSteroids & IV immunoglobulinsFresh frozen plasma (FFP)Frusemide

Consider each patient as a dengue patient,

as its presentation is changed.

Avoid all NSAIDs & steroids.

Correct diagnosis during early febrile phase

improves the prognosis.

Identifying the beginning & the end of the critical phase is a key factor in guiding fluid therapy in DHF.

Correct fluid management during the critical phase is the most important.

Pulse pressure, HR, HCT & UOP

Be concern about the possible complications.

THANK YOU