Dengue Fever Flashcards
Subtypes of Dengue Fever
DENV-1, DENV-2, DENV-3, DENV-4 serotypes; Therefore, possible to be infected four times.
Common name for Dengue Fever
- Breakbone fever
- Saddleback Fever
Where is Dengue Fever prevalent
- Endemic in tropics & subtropics & >100 countries worldwide+ Puerto Rico, Virgin Islands, US-affiliated Pacific Islands.
- Outbreaks occurred in FL/HI/TX.
Predisposing factors for Dengue Fever
- Urban environments
- outdoor activities during spring & summer
- mosquito bites
How is Dengue trasnmitted
- Aedes aegypti mosquito
- Mother to Child
- Blood transfusion/organ donation (rarely).
Can Dengue fever be prevented by vaccination
Yes, but only given to previously infected sero-confirmed individuals
What percentage of patients with Dengue are asymptomatic
75%
What percentage of patients with dengue present with mild to moderate, nonspecific, acute febrile illness, characterized by fatigue & malaise.
25%
What percentage of people infected with dengue progress to threatening severe dengue
5%
What are the 3 phases of Dengue
Febrile
Critical
Convalescent
Which phase of Dengue Fever:
- Typically lasts 2–7 days and can be biphasic.
- Severe headache; retroorbital pain; muscle, joint, and bone pain; & macular or maculopapular rash.
- Minor hemorrhagic manifestations, including petechiae, ecchymosis, purpura, epistaxis, bleeding gums, hematuria, or a positive tourniquet test result.
Febrile Phase
Which phase of Dengue Fever:
- Begins at defervescence and typically lasts 24–48 hours.
- Most patients clinically improve during this phase and move on to recovery & convalescence stage.
- Those with substantial plasma leakage develop severe dengue as a result of a marked increase in vascular permeability.
Critical Phase
Critical phase of dengue can develop into what kinds of dengue?
- Dengue Hemorrhagic Fever
- Severe Dengue Fever
- Dengue Shock Syndrome
During the critical phase of dengue, hypotension develops, systolic blood pressure rapidly declines, and irreversible shock and death may ensue despite resuscitation efforts
Dengue Shock Syndrome
During the critical phase of dengue, plasma leakage is a cardinal feature of what kind of Dengue Fever
Dengue Hemorrhagic fever
Which phase of Dengue Fever:
- Plasma leakage subsides
- Patient begins to reabsorb extravasated intravenous fluids, pleural, & abdominal effusions.
- Patient continues to improve, hemodynamic status stabilizes and diuresis ensues.
- 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.
- Convalescent-phase rash may desquamate and be pruritic.
Convalescent Phase - Recovery Stage
What are 2 hall marks of severe dengue
- Infection-induced capillary permeability (leaky capillaries)
- Disordered/diminishedblood clotting.
What causes leaky capillaries and disordered/diminished blood clotting in dengue
- Leaky capillaries (in the critical phase) occurring secondary to an immune system response to the virus.
- Dengue-infected cells becomenecrotic, and then affect both coagulation (blood clotting) andfibrinolysis(breakdown of clots)
- Low platelet count degrades the normal clotting response.
Why would you do the TQ test?
- General determination of a patients’ capillary fragility or hemorrhagic tendency.
- Fairly effective test used to further justify a presumptive Dengue Diagnosis without the ability or access to confirmatory laboratory testing.
Describe the TQ test for dengue
- Obtain baseline BP & annotate the readings. Then, let the arm a rest for 90-120 seconds.
- Attach BP cuff, and inflate to a point midway between the Systolic & Diastolic pressures obtained at baseline.
Example: Baseline BP was 120/80; cuff will be inflated to 100 mmHg - Keep inflated cuff on arm for 5 minutes, then deflate & wait 2 min.
- Count petechiae below AC fossa.
- A positive test is 10 or more petechiae per 1 square inch.
Dx criteria for dengue fever
- Diagnosis can be made via clinical approach. Should consider dengue in a patient who was in an endemic area within 2 weeks of symptom onset.
- Laboratory confirmation can be made directly from a single acute phase serum specimen of viral components obtained early (≤7 days after fever onset)
- Later in the illness (≥4 days after fever onset), IgM against dengue virus can be detected with ELISA.
Treatment of dengue
- Ensure patient stays well hydrated and avoid aspirin, aspirin-containing drugs, and NSAIDS because of their anticoagulant properties.
- Invasive medical procedures such as NG intubation,intramuscular injectionsand arterial punctures are avoided due to bleeding risk
- Fever should be controlled with acetaminophen (Max 4g in 24 hrs.)
- Febrile patients should avoid mosquito bites to reduce risk of further transmission.
Antiviral treatment for dengue
none :(
Severe dengue treatment
- Typically requires ICU-level monitoring & blood products.
- Maintenance of the patient’s body fluid volume is critical for severe dengue care
Prevention of Dengue Fever
- No prophylaxis is available to prevent dengue.
- Risk increases with duration of travel and disease incidence in the travel destination (such as during the rainy season and during epidemics).
- Travelers going toareas with risk of dengueshould take steps toavoid mosquito bites.
Disposition of dengue
- MEDEVAC – Med advice on further management while awaiting MEDEVAC.
- Patients presenting with signs/symptoms (S/S) of even mild dengue should be evacuated to definitive medical care facility as soon as possible.
