Chikungunya Fever Dengue Fever/Dengue Haemorrhagic Fever ...
Dengue fever
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Transcript of Dengue fever
DENGUE FEVER
DEFINITION
EPIDEMIOLOGY
AETIOLOGY
Caused by 4 distinct but related viruses, DEN- 1/2/3/4- classified under Flaviviridae family
ssRNA viruses, enveloped and spherical (50 nm)Infection by one type confer lifelong immunity
towards that type, but only partial towards other type.
Evidence increase risk for DHF if there is sequential infection
Vector : Aedes aegypti (main), Aedes albopictus & Culex quinquefasciatus
A.aegypti (day-time bitting mosquito)
-must be infective female
-prefer feeds on human (abundant around human.
-breeds in clear water
-bitting activity reduced in low temperature
14ºC(transmission less in winter)
Transmission
Classification
Clinical Manifestation
Dengue Fever- 1◦ Infection with DEN-2 and DEN-4 are thought to be
inapparent, regardless of age- 1◦ infection with DEN-1 & DEN-3 in adult produces
biphasic fever and rash.- Manifestation varies, in infant & young child –asymptomatic to 1-5 days
fever, rhinitis, mild cough, pharyngeal inflammationIn classic dengue fever
- after incubation 2-7 d, rapid & sudden onset of fever
Accompanied by frontal or retro-orbital headacheBack pain (precedes fever,occassionally)Macular rash (transient, generalized,in first 2 days of
fever)Pulse rate is slow ( in proportion to fever)Myalgia ( increase in severity)Nausea & vomiting (on 2-6 D of fever) Generalized Lymphadenopathy , followed by of period of
Defervescence.Generalized mobiliform, maculopapular rash(palm &
soles spare)- disappear in 1-5 D (Biphasic ◦C curve)
At any stage, petechiae,epistaxis & purpuric lesion occur (not common)
After febrile stage, prolonged asthenia, bradycardia & extrasystole note( common in adult)
Dengue Hemorrhagic Fever( DHF).
~Other suggestive signs: hepatomegaly, circulatory disturbance, hematocrite fall after fluid replacement
Clinical Manifestation
Dengue Hemorrhagic Fever (DHF/ DSS) An acute vascular permeability syndrome followed with
abnormal in hemostasis.Progression of illness is characteristics (in children).In mild 1st phase: abrupt onset of fever, malaise,
cough, vomiting, headache & anorexia ( after 2-5 Days of rapid deteroriation & physical collapse)
In 2nd phase: has clammy hand, cold, warm trunk. Flush face & diaphoresis.
Restlessness, irritated, complained of mid-epigastric pain.
Peripheral cyanosis may occur.
Scattered petechiae on forehead, extremities, spontenous ecchymoses, easy bruising and bleeding at site of venupuncture( common findings).
Respiration is rapid & often laboured.The pulse pressure is usually narrow (≤20 mmHg),
systole & diastolic pressure may be low or unobtainable.Liver become tender ( 2-3 fingerbeadth below costal
margin, firm & nontender)Bilateral or unilateral pleural effusion (radiograph)After 2-3 Days of crisis, convalescence is rapid in
children who recovered.Temperature may return to normal during or before
shock.
PATHOGENESIS
On micrscopic exam.maturation arrest of megakaryocytes in BM( D/t vasoactive amines )
Diagnosis
WHO Grading of DHF/DSS
Grade 1 Grade 2 Grade 3 Grade 4
-Fever with constitutional symptoms.-Positive Hess test
-Spontenous bleeding(skin±other bleeds) in addition to manifestation of Grade 1
-Circulatory failure (rapid weak pulse, narrow pulse pressure <20mmHg, but systolic BP still normal.
-Profound shock (hypotension, undetectable BP & HR).
-Grade 3 & 4 is Dengue Shock Syndrome (DSS).-Thrombocytopenia & hemoconcentration differentiate Grade 1 & 2 of DHF from DF.
Investigation
TREATMENT & MANAGEMENT
Dengue Fever: Mostly supportive.Antipyretic drugs or cold sponging (< 40ºC).Fluid & electrolyte are given when necessary.Aspirin is contraindicated ( avoid Reye Synd.)
DHF/DSS: No antiviral given, only supportive measures.Antipyretic to avoid convulsion .Fluid intake is monitored (by mouth)
Observe sign of shock in children.Oral & parenteral fluid therapy for rehydration (to correct
metabolic aacidosis or dehydration).
ShockNeed admission.obtainIV access. & resuscitate.Monitor : vital signs, PCV, ABG, BP hourly until stable,
platelet count 6 hourly, BUSE & urine output.Fluid maintenance- continue with .45%saline 5%
dextrose(1-2 maintenance)
Electrolyte and metabolic disturbance.
-correction of hypoglycemia.Transfusion of blood & blood products.Monitor coagulation profile.O2 supplement.Vitamin K & H2 antagonist.
Prevention & Control
-Education
Prognosis
Only 1/3 of DHF patient develop shock and circulatory failure ( outpatient Tx is enough , bring back when there are alarming signs) .
Early plasma, fluid & electrolyte replacement proved to have favourable outcome( maintain circulation).
In DHF/DSS case, great care taken to reduce invasive procedures while managing shock.
In children,
-in shock with unobtainable BP,
-in shock but delayed admission,
-in shock with GIT bleeding
Has poor prognosis