Dengue Fever: A Guide

DENGUE
FEVER
Amila Weerasinghe
MBBS Undergraduate
2010/2011 Batch (21st )
Faculty of Medical Sciences
University of Sri Jayewardenepura
Sri 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.

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

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

2 – 7 days of illness + high grade fever
Headache
Retro – orbital pain
Myalgia
Arthralgia
Rash & haemorrhagic manifestations
positive tourniquet test
petechiae

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

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 Right
Lateral 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.
Complications
Fluid overload
Hypocalaemia
Nosocomial 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 mins
Diluted in equal volume of NS
Repeat 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 goal
plasma 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 normal
3% NaCl if Na+ < 120meq/l

Vit K IV
 3mg <1yr
 5mg 1-5yrs,
 10mg >5yrs
 IV Phenobarbitone - cerebral metabolism
Controls seizures
 Gut cleaning
NG tube
Antibiotics – Metranidazole
Lactulose

Platelet transfusion
Recombinant factor vii
Inotrops
Steroids & IV immunoglobulins
Fresh 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.

Dengue Fever: A Guide

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