Dengue fever

Question 1

What causes dengue fever

Answer 1

Arboviral illness spread by culicine mosquitos - aedes aegypti and aedes albopictus esp

Question 2

Where is dengue endemic to

Answer 2

South east asia and south america

Question 3

What is severe dengue

Answer 3

Severe bleeding
Organ impairment
Plasma leakage

Question 4

Where is denue endemic

Answer 4

South east asia
South and central america

Question 5

Types of dengue

Answer 5

Without warning signs
With warning signs
Severe

Question 6

Probable dengue criteria

Answer 6

Live in/travel to dengue endemic area
Fever +
-Nausea, vomit
-Rash
-Aches and pains
- + tourniquet test
-Leukopenia
-Any warning sign

Question 7

Warning signs dengue criteria

Answer 7

Abdo pain or tenderness
Persistnet vomitting
Clinical fluid accumulation
Mucosal bleed
Lethargy, restlessness
Liver enlargement >2cm
Haematocrit increase w rapid decrease and rapid decrease in platelets

Question 8

What bloods suggest dengue with warning signs

Answer 8

Rapid increase haematocrit, rapid decrease in platelets - extravasation of plasma

Question 9

Crtieria for severe dengue

Answer 9

Severe plasma leakage - shock - DSS, fluid acc -> resp distress
Severe bleeding
Sev organ involvement
Liver AST or ALT >1000
CNS - impaired consciousness
Heart and other involvement

Question 10

Phases of dengue

Answer 10

Febrile
Critical
Recovery

Question 11

6 factors determining phase of dengue

Answer 11

Temperature
Oral intake
Urine output
WBC
platelet
HCT

Question 12

Febrile phase features

Answer 12

4 days - high temp, normal bloods

Question 13

Critical phase length

Answer 13

day 4-6
WCC and platelte drop
Haematocrit increase - concentrated

Question 14

Recovery phase dengue featires

Answer 14

Reabsorption of fluid
Recovery of platelet, neutrophil and haematocrit count

Question 15

WHy important to not overload fluid in recvoery phase

Answer 15

Reabsorption of plasma that was extravasated

Question 16

What viral test use in febrile phase of dengue

Answer 16

PCR - high viraemia at this phase

Question 17

When do IgG tests for dengue become positive

Answer 17

At end of febrile phase and start of critical phase

Question 18

What is fluid loss from in febrile vs critical phases degnue

Answer 18

Febrile - poor oral intake
Insensible
Vomit and diraahoea

Critical - leaking nad bleeding + all of above

Question 19

What diagnostic tests can use <5 days post fever onset

Answer 19

Viral RNA - RT- PCR
Virus antigen test - NS1
ELISA

Question 20

Diagnositc tests>5 days post fever onset

Answer 20

IgM antibodies

Question 21

What combination of diagnostic tests use in real life and why

Answer 21

RT-PCR + IgM
OR NS1 + IgM
Extend detection actue dengue to 10 days post fever onset

Question 22

Principle of management of denfue

Answer 22

Correct dehydration in febrile nad critical phases
Prevent fluid overload in recovery phase

Question 23

Initial presentation of dengue fever

Answer 23

Intermittent high pyrexias - break bone fever 3-7 dyas
Arhtralgia
Rash - blanching maculopapular erythematous rash (measles similar) may -> petechiae
Bleeding, gums, epistaxis, GI bleeds
Headache
Nausea & vomiting
Lymphadenopathy
Generalised myalgia
Backache
Ocular manifestations:
Retro-orbital pain
Conjunctival injection
Conjunctivitis

Question 24

Symptoms of severe dengue

Answer 24

Pulmonary and facial oedema
Ascites
Pleural effusions
Meningism including photophobia
Worsening or more profuse haemorrhage

Question 25

Bloods in dengue

Answer 25

Prolongation of APTT and PT
Deranged U&E’s
Elevated LFTs especially AST

Question 26

Tourniquet test postive sign

Answer 26

1/3 positive
BP cugff - halfway between systolic and diastolic for 5 mins
+ 20+ petechiae in 2.5cm square on forearm

Question 27

What meds avoid in dengue

Answer 27

Aspirin - increased haemorrhage risk and reyes syndrome in children

Question 28

Complications of dengue

Answer 28

50% mortality if untreated
severe multi-organ involvement, haemorrhage and shock.
Hepatic failure
Encephalopathy
Myocarditis
Disseminated intravascular coagulation
Septicaemia

Question 29

Incubation period dengue

Answer 29

4-10 dyas

Question 30

What subtypes ass w severe disease

Answer 30

DEN 2 and 3
Secondary infection (different serotype) - antibody dependent enhacement