Dengue Fever Flashcards
What is the common name for dengue fever?
Breakbone fever
Predisposing Factors for Dengue Fever
Urban environments, outdoor activities during spring & summer; mosquito bites
Dengue fever is Transmitted Via….
Aedes aegypti mosquito
Mother to child
Blood transfusion/organ donation (rarely).
Scientific name for Dengue Fever
Denguevirus (DENV)
What is the subtypes of DENV?
DENV-1, DENV-2, DENV-3, DENV-4
How is it possible to get infected four times with dengue?
Because there are four subtypes
What percentage of Dengue Fever of infections present with symptoms?
25%
What are the 3 Phases of Dengue fever?
(a) Febrile phase
(b) Critical phase
(c) Convalescent phase
What phase of Dengue?
(1) Typically lasts 2–7 days and can be biphasic.
(2) Signs and symptoms may include severe headache; retroorbital pain; muscle, joint, and bone pain; & transient maculopapular rash.
(3) Minor hemorrhagic manifestations, including petechiae, ecchymosis, purpura, epistaxis, bleeding gums, hematuria, or a positive tourniquet test result.
Febrile phase
What phase of Dengue?
(1) This phase of Dengue begins at defervescence and typically lasts 24–48 hours.
(2) Most patients clinically improve during this phase and move on to recovery & convalescence phase.
-(a) Thus, these patients really don’t have a critical phase, per se,
and go from febrile phase to recovery stage.
(3) However, those with substantial plasma leakage develop severe dengue as a result of a marked increase in vascular permeability.
-(a) Plasma leakage is a cardinal feature of Dengue Hemorrhagic Fever.
Critical phase
What phase of Dengue?
(1) This phase of Dengue begins at defervescence and typically lasts 24–48 hours.
(2) Most patients clinically improve during this phase and move on to recovery & convalescence phase.
-(a) Thus, these patients really don’t have a critical phase, per se,
and go from febrile phase to recovery stage.
(3) However, those with substantial plasma leakage develop severe dengue as a result of a marked increase in vascular permeability.
-(a) Plasma leakage is a cardinal feature of Dengue Hemorrhagic Fever.
Critical phase
Plasma leakage is a cardinal feature of what?
Hemorrhagic Fever.
What Dengue issue?
Hypotension develops, systolic blood pressure rapidly declines, and irreversible shock and death may ensue despite resuscitation efforts
Dengue Shock Syndrome
What phase of Dengue?
(1) As plasma leakage subsides, patient enters this phase.
(2) Patient begins to reabsorb extravasated intravenous fluids, pleural, & abdominal effusions.
(3) As a patient continues to improve, hemodynamic status stabilizes and diuresis ensues.
(4) The patient’s hematocrit stabilizes or may fall because of the dilutional effect of the reabsorbed fluid, and the white cell count usually starts to rise, followed by a recovery of platelet count.
(5) this phase; rash may desquamate and be pruritic.
Convalescent phase (Recovery stage)
Two hallmarks of Severe Dengue are….
infection-induced capillary permeability (leaky capillaries) and disordered/diminished blood clotting
What are the 3 main reasons for the two hallmarks of Dengue fever
(a) Leaky capillaries (in the critical phase) occurring secondary to an immune system response to the virus.
(b) Dengue-infected cells become necrotic, and then affect both coagulation (blood clotting) and fibrinolysis (breakdown of clots).
(c) Low platelet count degrades the normal clotting response.
What is a relatively accurate way to get a general determination of a patients’ capillary fragility or hemorrhagic tendency?
Tourniquet Test (or capillary fragility test)
How is a Tourniquet test done?
- Obtain baseline BP, rest for 90-120 sec
- Inflate to in-between SBP/DBP
- Leave inflated for 5 min then wait for 2 min
- count petechiae below AC fossa
- A positive test is 10 or more petechiae per 1 square inch
What is a Positive tourniquet test?
10 or more petechiae per 1 square inch
Should consider dengue in a patient who was in an endemic area within how many weeks of symptom onset?
two
Laboratory confirmation can be made when and from what?
Within 7 days of onset, acute phase serum specimen
Later in the illness (≥4 days after fever onset), IgM against dengue virus can be detected with ______
ELISA
True/False
Specific antivirals are available for dengue
False
Dengue Fever – Treatment
-Ensure patient stays well hydrated
-Fever should be controlled with acetaminophen
-Febrile patients should avoid mosquito bites to reduce risk of further transmission.
Dengue Fever Contraindications
-avoid aspirin, aspirin containing drugs, and NSAIDS because of their anticoagulant properties.
-Invasive medical procedures such as NG intubation, intramuscular injections and arterial punctures are avoided due to bleeding risk
Severe Dengue Management
(a) Typically requires ICU-level monitoring & blood products
(b) Maintenance of the patient’s body fluid volume is critical for
severe dengue care
What is the Prophylaxis available to prevent dengue?
No prophylaxis is available to prevent dengue
Dengue Fever – Disposition
MEDEVAC – Med advice on further management while awaiting
MEDEVAC
-Patients presenting with signs/symptoms of even mild dengue should be evacuated to definitive medical care facility as soon as possible.
