Dengue fever Flashcards
What is dengue fever?
Self limiting flu-like illness
Caused by dengue virus - type of flavivirus
What is dengue fever spread by and where?
Aedes aegyptu
Aedes albopictus
Southeast Asia, africa, Pacific and Americas
Four serotypes of dengue virus
DEN-1
DEN-2
DEN-3
DEN-4
How do serotypes and imunity to degnue work?
Life long immunity after ill
If prev immunity to one serotype and infected by another -> severe dengue
How do serotypes and imunity to degnue work?
Life long immunity after ill
If prev immunity to one serotype and infected by another -> severe dengue
Incubation for dengue
2-7 dyas
Phases of dengue fever
Febrile phase
Critical
Recovery
Phases of dengue fever
Febrile phase
Critical
Recovery
Risk factors
Live/travel endemic areas
Poor public hygeine
High population density
Febrile phase clinical features
High grade fever
Maculopapular rash
Facial flushing
Muscle and joint pains
Severe headache
Retro-orbital pain
Nausea and vomitting
How long is febrile phase dengue
2-7 days
How long is febrile phase dengue
2-7 days
Clincal examination findings febrile phase dengue
Maculopapular rash sparing palms and soles
Clincal examination findings febrile phase dengue
Maculopapular rash sparing palms and soles
Clincal examination findings febrile phase non severe dengue
Maculopapular rash sparing palms and soles
Positive tourniquet test
What is a positive tourniquet test?
there is >20 petechiae per 2.5cm.2
Critical phase how long last and what it is?
After third day fever
Lasts 24-48 hours
Increase in capillary permeability with drop in body temperature
Symptoms of critical phase
Severe abdominal pain
Persistnet vomitting
Rapid breathing
Lethargy
Altered LOC
Restlessness
Dengue with warning signs what not to miss
Haemorrhageic manifestatiosns
=Petechiae, mucosal, membrane bleeding na d menorrhagia
Enlarged and tender liver
Evidence of shock - prolonged cap regill time
Signs of severe dengue
Clinical fluid accumulation = pleural effusion, ascites
Periorbital oedema
Hypovolaemic shcol
Severe bleeding
Signs of severe dengue
Clinical fluid accumulation = pleural effusion, ascites
Periorbital oedema
Hypovolaemic shcol
Severe bleeding
Recovery phase time and signs
Leaked plasma reabsorbed into blood
48-72 hours
‘isles of white in a sea of red’
Severity classes dengue
Probable dengue
Dengue with warning signs
Severe dengue
Severity classes dengue
Probable dengue
Dengue with warning signs
Severe dengue
What is the criteria for probable dengue
1 - Live in or travel to dengue endemic areas
2 - fever
3 - 2 of follwong:
-N+V
-Rash
-Aches and pains
-Positive tourniquet test
-Leukopenia
-Any warning sign
Dengue with warning signs
1 - Abdominal pain
2 - Persistent vomitting
3 - Clinical fluid accumulation
4 - Mucosal bleed
5 - lethargy
6 - restlessness
7 - tender liver
8 - increase in haematocrit with rapid decrease in platelet count
Severe dengue criteria
1 - Severe plasma leakage
-Dengue shock syndrome
-Fluid accumulation with respiratory distress
2 - Severe haemorrhage
3 - Severe organ impairement
-Liver impairment
-CNS impairment
-Cardiac failure
Differential diagnosis
Malaria
Typhoid fever
HIV seroconversion
Infectiours mononucleosis
Measkes
Erythe,a infectiosum
Chikungunya
Zika virus
COVID-19
How to investigate denfue fever
BP
FBC, LFTs, U+Es, coag screen
CXR
NSI antigen test
IgM antiboides with ELISA
IgG antibodies with ELSIA
What look for in FBC, LFT, U+Es?
-Raised haematocrit and low platelet count suggests dengue warning signs (may also present with neutropenia + leukopenia)
-Raised ALT and AST - organs involved
Coag - prolonged APTT + PT
When is NSI antigen detected?
First 4 days og illness
When are IgM antibodies for dengue detected?
After 5 days os illness
Peaks 2 weeks after onset symptoms
When are IgG antibodies detected and what used for
After 7 days of illness, lasts for life - used to confirm secondary infection
Key management of dengue
PHE notify
Control fever with paracetemil
IV fluid resus w close monitor - prevent overload
Escalate patients with warning signs and severe dengue to secondary facility
Prevention of dengue
Wear long sleeved clothes
Insect repellent
Remove soruces of breeding sites
Complications of dengue
Dengue haemorrhagic fever
DIC
Dengue shock sundreom
Severe organ involvement eg cardiac failure, liver impairment
Effects of dengue in pregnancy
Death of foetus
Low BW
Prematurity
Effects of dengue in pregnancy
Death of foetus
Low BW
Prematurity
