3. EPIDEMIOLOGY
Latest
updated
on
August:
From January to Aug 6, 2021, a total of
16,565 dengue cases were reported
compared to 63,988 in the same
in 2020, which is a reduction of 47,423
cases or 74.1 per cent.
"The average weekly dengue cases
reported so far is 534 cases a week,
compared to 1,700 a week in 2020 and
2,500 a week in 2019.
4. VIROLOGY
Dengue infection dengue virus (mosquito-borne flavivirus)
Transmitted by Aedes aegypti & Aedes albopictus
Serotypes : DENV-1,2,3 and 4
Each episode of infection induces a life-long protective immunity to the homologous serotype but only partial and
transient protection against other serotypes
5. COURSE
• Incubation period is 4-7 days (range 3-14)
• It may be asymptomatic or may result in a spectrum of illness ranging from
undifferentiated mild febrile illness to severe disease, with or without
plasma leakage & organ impairment
• Symptomatic dengue infection is a systemic and dynamic disease with
clinical, hematological and serological profile changing from day to day
• After the incubation period, the illness begins & followed by :
Febrile, critical and recovery phase
6. FEBRILE
Last 2-7 days
• facial flushing , rash
• generalised body ache
• vomiting, headache
• petechiae, mucosal
membrane bleeding , PV
bleeding, GI bleeding
• tender liver
FBC bicytopenia : WCC <7,
PLT <150
Tender liver
*tourniquet test
Time
Characteristic
Blood
investigations
Warning signs
CRITICAL
Last 24-48H (occurs 3rd day of
fever, may occur earlier)
• Rapid drop in temperature
(defervensce)
1. Increase in capillary
permeability Plasma
leakage compensated/
decompensated shock
2. Decrease plasma volume
PLT <150 & increase HCT
• Altered GCS
• Restlessness
• Mucosal bleed
• Fluid accumulation
• Tender liver
• Abdominal pain
• Persistent GI loss
RECOVERY
After 24-48H of critical phase
• Plasma leakage stops
followed by reabsorption
• Well being improves
• Appetite returns
• Haemodynamically stbale
• Isles of white in the sea of
red
WCC & HCT levels stabilize
In some instances, organ
dysfunctions may worsen
• Hepatitis
• Encephalitis
• ICB
7.
8.
9. Tourniquet Test
The sensitivity of
the test: 0% to
57%, depending
on the phase of
illness and how
often the test
repeated, if
negative.
5-21% of patients
with dengue like
illness had
positive
tourniquet test
but subsequently
have negative
dengue serology
A recent study demonstrated that
there was 95.3% positive
predictive value if fever, positive
tourniquet test, leucopenia/
thrombocytopaenia/
haemoconcentration were used as
screening criteria.
10. PLASMA
LEAKAGE
Acute increase in vascular permeability leakage of plasma into
extravascular compartment haemoconcentration hypovolaemia /
shock tachycardia & generalised vasoconstriction due to increased
sympathetic output
Clinical manifestations of vasoconstriction :
• Skin - coolness, pallor, delayed CRT
• CVS - raised DBP, narrowing of PP
• Renal system - reducing UO
• GI system - persistent vomiting & diarrhoea, abdominal pain
• CNS – lethargy, restlessness, reduced consciousness level
• Respiratory – tachypnoeic ( RR > 20 )
11.
12. • Inadequate perfusion of the tissue increased anaerobic glycolysis &
lactic acidosis
• Late complications of prolonged shock :
• massive bleeding
• disseminated intravascular coagulopathy (DIC)
• multi-organ failure
13.
14.
15. MEDICAL COMPLICATIONS SEEN IN
DENGUE PHASES
Febrile : dehydration. High fever cause neurological disturbancs
and febrile seizures in young children
Critical : shock from plasma leakage : severe haemorrhage and
organ impairment
Recovery : hypervolaemia (only in IV Fluid therapy has been
excessive and/or has extended into this period) and APO.
16. Clinical evaluation of the patients involves 4 STEPS
1.History taking
2.Clinical examination
3.Investigations
4.Diagnosis and assessment of disease phase and
severity.
Clinical evaluation
17. STEP 1 : HISTORY
A patient’s history should include:
• Date of onset of fever
• Oral intake
• Assess of warning signs
• Change in mental state/ seizure/ dizziness
• Other important relevant histories :
1. Family or neighbourhood history if dengue
2.Jungle trekking or swimming in waterfall : Consider leptospirosis,
typhus and malaria
3.Travelling (consider covid 19)
4.Recent unprotected sexual or drug use behavior : Consider acute
seroconversion illness
5.Co-morbidities (consider sepsis particularly in patients with DM)
19. STEP 3 : INVESTIGATIONS
1. Full blood count (FBC)
• Should done at the first visit to establish the baseline haematocrit. However, a
normal FBC during the first 72 hours of illness does not exclude dengue
infection
• Should be repeated daily from the 3rd day onwards until the critical phase is
over.
• A decreasing white blood cell and platelet count makes the diagnosis of
very likely.
2.Haematocrit (HCT) : A rising HCT is a marker of plasma leakage in dengue
infection. The median values of normal HCT level among Malaysian
populations are
• male < 60 years – 46%
• male > 60 years – 42%
• female (all age groups) – 40%
• Other important blood tests in disease monitoring are Liver Function Test
Renal profile (RP), coagulation profile, lactate and blood gases.
• Special tests such as Troponin and Creatine Kinase (CK) should be discussed
with the Specialists/Registrars before performing
3.Point of care test for dengue (Rapid combo Test ; RCT & NS1 Antigen /
20. 1. Rapid Combo Test
• detect the presence of virus as well as antibodies simultaneously. Generally RCT tests can be read within 15-20
minutes.
• Interpretation : presence or absence of bands for dengue NS1 antigen and dengue IgM and IgG antibodies.
These tests have a longer detection window as they can detect both the virus and antibodies, thus reducing the
possibility of false negative results.
• Useful during the early phase of onset when there is viraemia as well as at a later stage when antibodies against
dengue begin to rise. The sensitivity is 93.9% and specificity is 92%.
2. Dengue Antigen And Serology Tests By ELISA
• Non-Structural Protein-1 (NS1 Antigen)
• Dengue IgM & Dengue IgG test
3. Dengue Viral RNA Detection (Real time RT-PCR)
4. Virus Isolation : for research, surveillance and genotyping purposes.
Diagnostic tests
21. • NS1 antigen is a highly conserved glycoprotein that seems to be essential
for virus viability. Secretion of the NS1 protein is a hallmark of flavivirus
infecting mammalian cells and can be found in dengue infection as well
as in yellow fever and West Nile virus infection.
• False positive results have been reported in chronic diseases and
haematological malignancies.
• The detection rate is much better in acute sera of primary infection
(75%-97%) when compared to the acute sera of secondary infection
(60%-70%). The sensitivity of NS1 antigen detection drops from day 4-5
of illness onwards and usually becomes undetectable in the
convalescence phase.
• The presence of NS1 detection after day five may predict severe dengue
Non-Structural Protein-1 (NS1 Antigen)
22. • The IgM capture enzyme-linked immunosorbent assay (ELISA) is the
most widely used serological test. The antibody titre is significantly
higher in primary infections compared to secondary infections.
Once the IgM is detectable, it rises quickly and peaks at about two
weeks after the onset of symptoms, and it wanes to undetectable
levels by 90 days.
• In primary dengue infection, anti-dengue IgM can be detected
after five days of illness in approximately 80% of the cases.
93%-99% of cases will have detectable IgM from day 6 through day
10. In the event of a negative IgM result, a repeat serum should be
collected after five days.
Dengue IG M test
23. • However, in secondary dengue infections, IgM was detected in
among 78% of patients after day seven. IgM appears earlier or at
the same time frame but usually at lower titres compared to
primary dengue. This is possibly due to appearance of high levels of
anti-dengue IgG before or sometimes simultaneously with the IgM
response. Thus, 28% of all secondary dengue infections were
undiagnosed when only IgM was the only assay performed
• In primary and secondary dengue infection, dengue IgG was
detected in 100% of patients after day seven of onset of fever.
Therefore, a repeat dengue IgG is recommended if dengue IgM is
still negative after day seven with the negative IgG in the initial test
sample
Dengue IG G test
24. • The method is useful only during the viraemic stage of the disease
and can detect the viral RNA target up to five days after onset of
the symptoms.
• The test is useful for determination of circulating dengue serotypes
in the country.
• Limitations of RT-PCR are: This test is only available in a few
centres with facilities and trained personnel. The test is expensive.
The specimen requires special storage temperatures and short
transportation time between collection and extraction.
Dengue Viral RNA Detection (Real time RT-PCR)
25. • Dengue rapid combo test or NS1-Ag should be taken as soon as
dengue infection is suspected
• If dengue IgM is negative <7 days, a repeat sample must be taken
at recovery phase
• If dengue IgM is still negative >7 days, dengue IgG should be done
for diagnostic confirmation of secondary dengue infection
26. FALSE
POSITIVE
DENGUE
SEROLOGY
• Serological tests for dengue have been shown to
cross-react with:
• other flavivirus – Japanese Encephalitis
• non-flavivirus – malaria, leptospirosis, toxoplasmosis,
syphilis
• connective tissue diseases – rheumatoid arthritis
27.
28.
29. STEP 4 : DIAGNOSIS, DISEASE
STAGING & SEVERITY
ASSESSMENT
• Based on the evaluations of history,
physical examination and/or FBC and
haematocrit, the clinicians should be able to
determine:
• Likelihood of dengue infection
• The phase of dengue infection
(febrile/critical/recovery)
• Severity of the illness
30. PLAN OF MANAGEMENT
1. Dengue assessment checklist must be filled by the attending doctor
2. Notify the district health office followed by disease notification form
3. If admission is indicated
• Stabilise the patient at primary care before transfer
• Communicate with the receiving hospital/emergency department before transfer
4. If admission is not indicated
• Daily follow up is necessary especially from day 3 of illness onwards until the patient is afebrile for at least
24-48H without antipyretics
• Provide the patient with Outpatient Dengue Monitoring Record & Home Care Advice leaflet for Dengue
Dengue Patients
31. CLINICAL &
LABORATORY
CRITERIA FOR
PATIENTS WHO
CAN BE TREATED AT
HOME
• Able to tolerate orally well, good urine
output and no history of bleeding
• Absence of warning signs
• Physical examination
1. Haemodynamically stable
2. No tachypnoea or acidotic breathing
3. No tender liver or abdominal tenderness
4. No bleeding manifestations
5. No signs of third space fluid accumulation
6. No alterations in mental status
• Investigations : stable serial HCT
• No other criteria for admission (co-
morbidities, pregnancy, social factors)
32. WARNING
SIGNS
• Any abdominal pain/tenderness
• Persistent vomiting (>3X/24H)
• Persistent diarrhea (>3X/24H)
• 3rd space fluid accumulation (eg : ascites, pleural and
pericardial effusion)
• Spontaneous bleeding tendency
• Lethargy/restlessness/confusion
• Tender liver
• Raised HCT with rapid drop in PLT
HCT male <60 years – 46%
HCT male >60 years – 42%
HCT female (all age groups) – 40%
33. ADMISSION
CRITERIA
• Symptoms
• Warning signs
• Bleeding manifestations
• Inability to tolerate oral fluids
• Reduced urine output
• Seizure
• Signs
• Dehydration
• Shock
• Bleeding
• Any organ failure
• Special situations
• Patient with co-morbidities
(DM, Hypertension, IHD,
Coagulopathy, morbid
obesity, renal failure, CLD,
COPD)
• Elderly >65 years old
• Patients who are on anti-
platelet and/or
anticoagulants
• Pregnancy
• Social factors that limit follow
up (living far from healthy
facility, no transport, patient
living alone)
• Laboratory criteria : rising
HCT accompanied by
reducing PLT count
34.
35. EMERGENCY
TREATMENT
AND URGENT
REFERRAL
• Severe plasma leakage leading to dengue
shock
• Severe haemorrhages
• Severe organ impairment (hepatic damage,
renal impairment, cardiomyopathy,
encephalopathy or encephalitis
- During this period, plasma loss should be replaced
immediately ; IV Fuid therapy of 5 to 10 mL/kg of 0.9%
saline over 1 hour may be life-saving
