Dengu Fever by Dr Sarma
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Transcript Dengu Fever by Dr Sarma
Dengue Fever
(Pronounced as Dhen Gey)
A comprehensive presentation
by
Dr.R.V.S.N.Sarma., M.D.,
Alternative Names
Onyong- Nyang Fever
West Nile Fever
Break Bone Fever
Dengue like Disease
Background
Propagation of viral illnesses
Transmission of viral illnesses
Various families of Arbor viruses
Manifestations of Arborviral illnesses
Dengue – A Flavivirus- EM- Cell culture
Transmitted by mosquito
Aedes aegypti
Viral Illnesses - Propagation
Human
Zoonotic
Human
Accidental
Human
Arthropod
Virus
Rodent
Transmission of Viral Illnesses
Droplet infection as in case of
Measles, Influenza, Coryza etc.
Blood to blood transmission- HIV, HBV
Feco-oral – Rota, Polio
Direct contact – Herpes simplex etc
Arthropod borne –Dengue, JE, YF
Tick borne – CEE, Colorado TF
Arthropod borne Viral Diseases
Flavivirus – Mosquito borne – YF, DF,JE
Flavivirus – Tick Borne –CEE, RSSE, KFD
Buniyavirus – Mosquito- CE
Plebovirus – Sandfly Fever
Arinavirus – LCM virus
Colivirus – Colorado Tick fever
Vesiculovirus – Vesicular stomatitis
Alphavirus – E/W/V equine encephalitides
Manifestations of
Arborviral Illnesses
Most Arboviral diseases are rural
Arboviral illnesses cause typical
manifestations – Often overlap
The following clinical syndromes occur
FM – Fever – Myalgia complex
2. AR – Arthritis – Rash complex
3. HF – Haemorrhagic Fever
4. E – Encephalitis
1.
Epidemiology of Dengue
The Dengue Virus
The Vector
Global distribution of Dengue
Transmission cycle – host – vector
Propagation of virus – I.P
Natural History of Dengue
Dengue Hemorrhagic fever –
Endemicity pattern
Epidemiological Triangle
The Host
Interaction
The Virus
The Vector
The Agent
Dengue Virus
The Dengue Virus
Flavivirus
Positive sense
Single stranded RNA virus
40 to 50 nanometers
Four sero-sub types
Type 1 to 4
Arthropod borne
Dengue Virus
Electron Micrograms
Dengue Virus
Cell Culture
Of Dengue
Virus
The Vector
Aedes aegypti
(Infected Female Mosquito)
(rarely Aedes albapticus)
Peculiarities of A.aegypti
It is a day biting mosquito when normally
coils, repellents, nets etc are not used
It breads in fresh water around homes
Lays eggs preferentially in water jars, discarded containers, coconut shells, old tires etc.
Can transmit trans-ovarially the infection
Year round breeding 250 N to 250 S
Tropics and sub-tropics are its favorite zones. It
is an urban vector
Aedes aegypti
Dengue, YF, CGF
Aedes aegypti
Dengue
Yellow Fever
Chichungunya
Fever
Dengue on the Globe
Highly endemic
Recently acquired
Dengue Fever
Caused by an arthropod borne virus
It is a zoonotic virus
Man is accidentally infected
Other vertebrates are the reservoirs
Dengue virus has 4 subtypes 1 to 4
Positive sense, single str RNA- 40nm
Vector mosquito is Aedes aegypti
Mechanism of Transmission
Vector is infected after ingestion of blood
meal from a viremic vertebrate
Virus multiplies in the system of vector
for 2-3 weeks – extrinsic incubation pd.
Natural vertebrate partner has only
transient viremia and doesn’t suffer
Virus is injected by the A.aegypti into man
After 2-7 days of IP, man develops FM,HF
Dengue Transmission Cycle
Dengue Transmission
Dengue Illnesses - Propagation
Natural History of Dengue
In apparent
30%
Human Inf
DFM
Re infection
69%
10%
Secondary
Primary
DHF/DSS
DHF/DSS
01%
100% Recovery
95%
Death
5%
DHF Endemicity
Pathogenesis of DHF
Immuno-pathogenic
Cascade
Hypotheses on DHF - DSS
Neutralizing Ab are type specific
nutralize the homologous sub type
Subsequent infection with heterologous
sub type causes immune complexes
These Immune Complexes target the
mononuclear lineage foe enhanced viral
replication
Infected monocytes release vasoactive
mediators causing vascular damage
Initial Immunogenecity
Immune Complexes
Attack on Host Immune Cells
Immunopathogenic
Cascade of DHF/DSS
Macrophage – monocyte infection
Previous infection with heterologous
Dengue serotype results in production
of non protective antiviral antibodies
These Ab bind to the virion’s surface
Fc receptor and focus the Dengue virus
on to the target cells – macro/monocytes
T cell - cytokines, interferon, TNF alpha
The Disease
Clinical Features
Dengue Presentations
Undifferentiated fever
Dengue Fever (DF) with the FeverMyalgia (FM) presentation (classical)
Dengue Hemorrhagic Fever (DHF)
Dengue Shock Syndrome (DSS)
Hemorrhagic Manifestations
Skin hemorrhages:
petechiae, purpura, ecchymoses
Gingival bleeding
Nasal bleeding
Gastro-intestinal bleeding:
hematemesis, melena, hematochezia
Haematuria
Increased menstrual flow
Clinical Manifestations- DF
IP of 2 – 7 days - typical patient develops
Sudden onset of fever, chills, headache
Back pain with severe myalgia, arthralgia
Retro-orbital pain – break bone fever
Macular rash – in axillary area
Adenopathy, palatal vesicles, scleral inj.
Maculo-papular rash on trunk –
extremities
Epistaxis and scattered petechiae
Other manifestations- DF
Anorexia. Nausea, vomiting
In apparent illness-to acute incapacitation
Illness is about 2–5 days, biphasic course
Pain on eye movements
Pain on palpating abdominal muscles
Primarily not a respiratory illness
Rare - aseptic meningitis
Complete recovery is the rule - asthenia
Petechiae
Dengue Haemorrhagic Fever (DHF)
Vascular instability
Decreased vascular integrity
Assault on macro vasculature
Decreased platelet function
Increased vascular permeability
Vascular disruption and local bleeds
Hypotension, hemoconcentration- shock
DHF – Clinical Criteria
Criteria for DHF
Fever, or recent history of acute fever
Hemorrhagic manifestations
Low platelet count (100,000/mm 3 or
less)
Objective evidence of “leaky capillaries:”
Elevated hematocrit -20% or more
more over baseline or 50%
Low albumin, pleural effusion
Criteria for DSS
The four criteria of DHF
Evidence of circulatory failure
1.
2.
3.
4.
5.
Rapid and weak pulse
Narrow pulse pressue (less than 20mm)
Hypotension for the age
Cold clammy skin
Altered mental status
Four Grades of DHF/DSS
Grade 1
Fever, Const. Symptoms, +ve tourniquet test
Grade 2
Grade 1 + Spontaneous bleeding
Grade 3
Signs of circulatory failure
Grade 4
Profound shock - B.P. Pulse not recordable
Ecchymosis – Periorbital Edema
Large Subcutaneous Bleed
Capillary Damage
Tourniquet Test
Inflate blood pressure cuff to a point
midway between systolic and diastolic
pressure for 5 minutes
Positive test: 20 or more petechiae
per 1 inch² (6.25 cm²)
Tourniquet Test
Pleural Effusion
PEI = A / B x 100
Clinical tests for DHF
Petechiae after tourniquet test
Overt bleed from previous GI lesions
Platelet count less than 100,000/ul
Low pulse pressure, cyanosis, effusions
Hypotension, Shock
DHF- Poor Prognostic Signs
Girl children under 12 with DHF/DSS
Severe hypotension and shock
Multifocal bleeding – abdominal pain
CNS encepahlopathy, fits, coma
Watch for preorbital edema, proteinuria
postural or otherwise hypotension
Serotype 2 infection after type 4
Malnutrition is protective
Unusual Presentations of Dengue
Encephalopathy
Hepatic damage
Cardiomyopathy
Severe GI bleeding
Differential Diagnosis
FM complex
Anicteric leptospirosis
2. Rickettsial fevers
3. Influenza, Measles, Rubella
1.
DHF / DSS
Other hemorrhagic fevers
2. DIC due to septicemia
3. Complicated Malaria
4. Meningococcemia
1.
Laboratory Diagnosis
Complete Blood Counts
Hematocrit
Platelet Count
Serum GOT, GPT
Serum Albumin
Proteinuria, hematuria
Immunological Tests
Chest Skiagram
Laboratory Diagnosis
Leucopenia. Thrombocytopenia
Increased SGOT, SGPT
Rising Ab titre in paired sera
Antigen detection ELISA
IgM-capture ELISA within few hours
Reverse transcription PCR confirmatory
IgG ELISA significant of past infection
Immuno Detection Tests
ELISA Plate
IgM-capture ELISA
Treatment of DF
Supportive measures - Vector barrier
Avoid Aspirin and if possible NSAIDs
Steroids should not be used
Fluid replacement to avoid hemoconc.
Children below 12 require careful watch
for DHF / DSS
No antiviral agents are of proven value
DHF / DSS
Intensive Care
Oxygen
Rehydration
Barrier Nursing
Mosquito Screen
Common Misconceptions- DHF
Dengue + bleeding = DHF
DHF is fatal only due to hemorrhage
No Majority of deaths are due to shock
Poorly managed DF turns into DHF
Positive tourniquet = DHF
it is not specific for DHF,
it indicates capillary fragility of any origin
More Common Misconceptions
DHF is only a pediatric illness –
No, All ages may be involved
DHF is a problem of poor families –
No, in fact they may not have
immune complexes to required level
Tourists will get DHF –
No, in fact they are at low risk
Management of DHF/DSS
Close monitoring of hypotension/shock
Oxygen administration
IV. Infusion of crystalloids/colloids
Platelet transfusion
Clotting factors replacement
Case fatality is 5% in good centers
Fluid Balance
Continue monitoring after defervescence
Serial hematocrits, BP, Urine output
Fluid replacement is twice the requirement
1500 ml + 2 x (weight-20) – for 60 kg wt.
Eg. {1500 + 2 x (60-20)} x 2
= {1500 + (2x 40)} x 2 = (1500 + 800) x 2
= 2300 x 2 = 4600 ml = 10 pints
Immunization
Each serotype produces life long immunity
There is not efficacious vaccine available
Vaccine needs to be tetravalent
Live attenuated vaccines possible
Several candidate vaccines are on trials
It may be harmful to vaccinate in view
of the pathogenesis of DHF/DSS
Vector Control
Biological
Largely experimental
2. Use of fish to feed on larvae
1.
Environmental
Elimination of larval habitat
2. Most likely successful strategy
1.
Purpose of control
To reduce female vector density
Vector Control of Dengue
Mosquito control is expensive –impossible
Destruction of breeding sites – viable
Spraying insecticides for adult control- ?
Individual measures to avoid vector contact
Mosquito screens, repellents (DEET)
2. Permithrin impregnated clothing
1.
Non degradable tires, long life plastics-avoid
Challenge
Achieve active community involvement
Solicit input from the earliest program
planning stages
Encourage community ownership
True community participation is key
Bibliography
World Health Organization Reports
Pan American Health Organization
Center for Diseases Control, Atlanta
National Institute of Communicable
Diseases, New Delhi
Bangladesh Center for Dengue
Harrison's Principles of Internal
Medicine, 15 ed.
Together We Learn Better
Each Patient is a Book
Each Day is a Learning Opportunity
CME has More Relevance
Now Than Ever
Reach Yours Sincerely @
Dr.SARMA RVSN
Voice : +91-4116-2309226, 260593
Mobile : +91- 93805 21221
E-mail : [email protected]
Web site : www.drsarma.in
Snail mail :
3, Jayanagar, Tiruvallur
Tamilnadu, INDIA
Pin : 602 001
Thank You !