Infections Flashcards
1
Q
Virology of DENV
A
- Arbovirus transmitted by arthropod vectors (Aedes aegypti).
- Family - flaviviridae
- Genera - flavivirus
- Serotypes - 4
- Genome - ssRNA
- Structural & Non-structural proteins
- Tropism - meningoencephalitis, hepatitis, haemorrhage
2
Q
DENV control strategies (integrated vector control)
A
- Physical - Remove breeding sites, bed nets
- Chemical - Weekly thermal fogging (OP/pyrethroids), Bacillus thuringiensis israeliensis spraying
- Biological - larvivorous fish
3
Q
Classification of DENV infection syndromes
A
A. Asymptomatic B. Symptomatic 1. Undifferentiated 2. DF with or without bleeding 3. DHF with or without shock (DSS) 4. Isolated organopathy
4
Q
Basic pathogenesis of DENV
A
- Incubation period 6 (3-14) days with viremia
- Febrile phase with inflammatory response
- Critical phase with capillary leak, thrombocytopenia and bleeding
- Recovery phase with return of appetite and convalescent rash and desquamation
5
Q
Detailed pathogenesis of DENV
A
1. DENV enters Langerhans, Dendritic cells ○ Endothelium apoptosis ○ Hepatocyte apoptosis/necrosis ○ Macrophage apoptosis ○ Haemopoesis suppression 2. Humoral response yields cross reactive antibodies ○ Anti PLT ○ Anti plasmin ○ Anti endothelium 3. Cell mediated response leads to Complement activation • Leads to ○ Coagulation disorder § Reduced PLT § Consumption coagulopathy § Plasmin activation § Complement activation ○ Fluid leakage 4. Endothelial dysfunction causes capillary leakage
6
Q
Symptoms of DENV febrile phase
A
• High fever 2-7 days • N V D • LOA • Severe headache • Retro-orbital pain • Myalgia • Arthralgia • Bone pain • Facial flushing • Blanching erythematous maculopapular rash • Bleeding manifestations • Petechiae, purpura • Mucosal bleeding • GI bleeding • Hematuria • HMB • Epistaxis Tourniquet test • Leucopenia - WBC <5000 Thrombocytopenia - 50% will have PLT <150,000 No plasma leakage but Rising HCT 10%
7
Q
Symptoms of DENV critical phase
A
• Defervescence by crisis (day 3/4) • Shock • Abdominal pain • Tender hepatomegaly • Pleural effusion PCF + HRPF Rising HCT (upto 20% from baseline)
8
Q
Symptoms of DENV convalescent phase
A
• Clinical improvement (return of appetite) • Convalescent rash • Generalized itching Diuresis • Stable HCT • Increasing WBC Increasing PLT
9
Q
Early detection of leakage in DENV
A
Abdominal pain Tender hepatomegaly WBC < 5000 Lymphocytosis PLT < 100 Progressively rising HCT
10
Q
Early detection of shock in DENV
A
Sweating Abdominal pain Persistent vomiting Restless Postural dizziness Low UOP
11
Q
Recognising stages of shock in DENV
A
Pre-shock • Tachycardia • CRFT > 2 sec • PP <25 mmHg • Tachypnea Compensated • Postural BP drop • Pulse pressure < 20 mmHg Decompensated • SBP < 90 mmHg • SBP drop > 20% Profound shock - BP not detectable
12
Q
DENV management in co-morbidities
A
- Liver failure - baseline LFT, PT INR, Albumin, judicious IV fluids because leak more. Give Vit K IV
- Heart disease - stop DAPT, do ECHO, Fluid overload is a problem
- DM - Convert to insulin, Monitor CBS to keep below <200mg/dL, monitor for DKA and if yes increase IV fluids
- CKD/AKI - Baseline U+E, Cr, ABG, eGFR, UOP, UFR monitoring. Fluid overload is common.
13
Q
Transferring a DENV patient
A
Transfer criteria
1. No facilities for CP monitoring 2. Prolonged shock needing ICU
How to transfer
1. IVF bolus
2. IV dextrose
3. Oxygen
4. Transfer form
a. IpOp
b. Ix
c. Rx
d. Temperature and monitoring charts
14
Q
Discharging a DENV patient
A
Discharge criteria
1. No fever for at least 24 hours without antipyretic 2. 2 days since recovery from shock 3. Good general condition and appetite improving 4. Normal HCT at baseline value (38-40%) 5. No SOB from pleural effusions 6. No ascites 7. PLT >50 8. No other complications
Discharge plan
2 - 6 months of rest
