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65 Cards in this Set
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- Back
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what is other names for and origin believed to be of Dengue
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Ka dinga pepo - being caused by evil spirit. Spanish - dinga - careful, bone pain, swahilili dinga - seizure
Dandy fever - WI, slaves of dandy posture - stiff leg |
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What has been called most important mosquito-transmitted viral disease in terms of morbidity and mortality
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dengue, second only to malaria as mosq-trans dx affecting humans.
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how many people live in areas at risk for epidemic
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2.5 mil
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How has DHF increased or decreased in americas
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50-fold inc 80's - 90's.
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how many serotypes for dengue
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4 DV -1,2, 3, 4 are most widespread arboviruses
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does dengue have a sylvanic cycle?
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no, lost need for enzootic cycle for maintenance
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reasons for dramatic global emergence of DF/DHF as concern
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1. major global growth and change - substandard housing, h2o, sewer, etc
2. PH infrastructure deteroriated 3.inc travel by plane transports infected. 4. no effective mosq control |
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describe PH infrastructure problems
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1. crisis mentality - respond rather than prevent
2. surveillance is passive ( not active, even in US) 3. Untrained Physicians 4. epidemic reaches peak before recognized |
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vector of dengue
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Aedes Aegypti
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describe dengue's emergence in americas
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major PH prob
50's and 60;s A Aegypti was eradicated in yellow fever erad, from C and SA erad program discontinued in 1970 in US Mosq began to reinfest 2002 - distrib much wider than before erad program |
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reasons for dengue exp in america
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1 extensive vector infestation with declining vector control
2 unreliable water supply sys 3 inc non-biodegradable containers and poor solid waste disp 4 inc air travel 5 inc pop density |
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describe virus in dengue
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arbovirus transmitted by mosquitoes - flavirus, single strand rna
4 serotypes 1-4 each serotype has specific lifetime immunity all Stypes can cause severe/fatal ds Genetic variants in each Stype appear more virulent and have greater epi potential |
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what are the vectors for dengue
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Aedes Aegyptii and A albopictus
Transmit by infected FEMALE daytime feeder peridomestic lays eggs and produces larvae in artificial containers (preferred) |
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what are three types, presentations of Dengue
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DF
DHF D Shock Syndrome |
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Symptoms of DF
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fever
headache muscle and joint pain N/V Rash Hemorrhagic manifestation |
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Other possible symptoms of DF
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metallic taste, itching, depression after acute phase
also diarrhea |
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Incidence; CFR
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tens millions/year - DF
hundred thousands/DHF case-fatality of DHF 5% CFR up to 30% with inadequate mgmt CFR can be reduced to 1% with early tx Most fatalities - kids/young adults |
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four dengue clinical yndromess
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UNDIFF FEVER
CLASSIC DENGUE FEVER DENGUE HEMORRHAGIC FEV DENGUE SHOCK SYNDROME |
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Incub time for DF
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4-7 (max 3-14)D
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Viremia - when start and how long last?
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starts just before onset of symptoms
lasts 5 days |
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Symptomatic time for DF
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3 - 10 d
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Describe clinical illness vs viremia in duration
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clinical lasts longer than viremia
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another name for Dengue
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breakbone fever
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clinical case def of dengue
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DF is acute febrile viral dx w/ ha, bone/joint pain/mm pain/rash and LEUCOPENIA!
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clinical case def for DHF
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1 fever or hx of acute fever
2 hemorrhagic manifestations 3 low platelet count (100K/mm3 or less) - 300 norm 4 obj evidence of 'leaky capillaries' |
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How are leaky capillaries determined?
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elevated hematocrit - 20% > over baseline
low albumin pleural effusions |
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WHO GRADES OF DHF - 4
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1 F/NONSPECIFIC CONST SYMPTOMS - + TOURNIQUE TEST/SCATTERED PETECHIAE
2 GRADE 1 + spont bleeding 3 signs circulatory failure 4 profound shock |
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what is criteria for pos tourniquet test
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20 or > petechiae/1 inch2
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what do you use for tourniquet test and how long and where placed?
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BP cuff/half way bet sys and dys for 5 min
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Pleaural effusion index
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PEI = A/B x 100
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DANGER SIGNS IN DHF
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abd pain - intense
persistent vomiting abrupt change fever - hypotherm restlessness or somnolence |
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first sign of intravascular volume depletion
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delayed cap refill
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what is a late sign in children in DHF
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hypotension
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CLINICAL DEF OF DENGUE SHOCK SYNDROME
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4DHF criteria +
1 circulatory failure a rapid/weak pulse b narrow pulse P or hypoT for age c cold/clammy skin and altered mental state FRANK SHOCK IS EVIDENCE OF CIRCULATORY FAILURE |
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DIC in Dengue
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child w DHF or DSS may be hypoT w DIC
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TX for DIC infant
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Crystalloid fluid resuscitation and DIC tx critical
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PATHOGENESIS OF DENGUE
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1 no X preotect btw serotypes
2 pop can have D-1 one year/D-2 next 3 most inf cause debilitating but nonfatal illness 4 some kids get severe/fatal form called DHF or DSS 5 Boosting of ABY rxn after 1st |
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important concept in Aby boosting
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presence of aby to one serotype of DV is believed to facilitate occurrence of DHF/DSS in certain individuals through immune-enhancement when infected by a second serotype -even after 20 years
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What is hyperendemic transmission
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higher risk in locations with 2 or more serotypes circulating simultaneously at high levels
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WHAT IS ANTIBODY-ENHANCEMENT AND ITS IMPORTANCE
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ADE - PROCESS CERTAIN STRAINS OF DV, COMPLEXED WITH NON-NEUTRALIZING ABYS, CAN ENTER > CELLS OF MONO LINEAGE, INC VIRUS PROD.
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DESCRIBE INFECTED MONOCYTES ACTIVITY
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RELEASE VASOACTIVE MEDIATORS, = INC VASCULAR PERMEABIOLITY & HEMORRHAGIC MANIFEST = DHF & DSS
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DESCRIBE NEUTRALIZING ABYS EFFECTIVENESS
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STRONGEST FOR ORIGINAL SEROTYPE
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Risk factors reported for DHF
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1 most cases self limited
2 DHF can occur in primary inf with certain genetic strains of virus 3 Pre-existing anti-dengue aby - MA or previous inf 4 host genetics -race may be factor 5 Age - SEA - kids/Americas - all ages |
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WHAT STRAINS BIGGEST RISK FOR DHF?
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DEN-2, DEN-3, DEN-4 THEN DEN-1
Second inf w Type 2 = highest risk for DHF |
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PROBABILITY OF DHF
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Hyperendemicity chart in notes...
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LAB TEST
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Routine - CBC, WBC, platelets, hemcr
albumin, liver func, urine Dengue specific virus isolation for serotype serology - ELISA, Immune Chroma acute/convalescent phase sera |
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How is virus isolation in tissue culture done
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FLUORESCENT CELLS
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OUTPATIENT TRIAGE
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Go home if: no Hem mani/well hydrate
Hosp or Outpt obs: hemorrhage mani or hydration borderline Hospitalized for sure: warning signs, DSS |
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EARLY WARNING SIGNS
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how many days since symptom onset?
DSS usually seen in 3-6 days after onset symptoms:SEVEN DAYS MEANS WORST IS PROBABLY OVER! |
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FEVER WARNING SIGNS
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If fever is btw 3 and 6 days after symptoms began, warning sign!
Shock often occurs at or around fever |
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OTHER WARNING SIGNS
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Drop in Platelet count, inc in hematocrit, or other signs of plasma leakage
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What do HEMOCONCENTRATION AND THROMBOCYTOPENIA mean for patient?
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If meets criteria for DHF, pt's risk category has changed. DF is rarely fatal, but DHF has > proportion of fatality
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DANGER SIGNS
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severe abdominal pain
change in mental status V abrupt change from Fever to hypotherm -SIGNAL ONSET DSS |
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WHAT IS GOAL OF TREATMENT
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PREVENT SHOCK, SUPPORT PT THRU PLASMA LEAKAGE AS WILL RESOLVE
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PATIENT FOLLOW-UP
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1 Pts @ home
danger signs, repeat clinical eval 2 Pts w/ bleeding manifestations serial hematcri/pltlet daily until temp normal for 2 days 3 All Pts if blood sample in 1st 5 days need convalescent day 6-30 all hosp pts need samples on adm & at discharge |
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TREATMENT DENGUE
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Fluids
Rest Antipyretics (no aspirin or NSIDS!) Monitor BP,Hemat, Pl count, consciousness level |
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Is the patient out of the woods once fever subsides?
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No, monitor for at least 24-48 hours following fever. if doubt, fluids, monitor bp, urine output, hemotocrit
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What are common Misconceptions about Dengue HF
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1 pediatric dx - all ages get it
2 dengue + bleeding = DHF - need 4 WHO criteria, cap permeability 3 DHF kills only by hem - pt dies due to shock 4 poor mgmt turns DF into DHF - DHF is distinct condition, even well treated pts can get it. 5 + tourniquet test = DHF tests indicates cap fragility only |
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Prognosis for children in shock or coma
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Treated promptly, can wake up and return to near normalcy within hours
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What are common post conditions
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continued bone pain, bradycardia and premature ventric contractions are common
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What is related to survival in Dengue
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early hospitalization and aggressive supportive care
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Is Dengue contagious person - person
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no
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Is there a vaccine
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no
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When expect dengue vaccine and what requirements?
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5-10 years/tetravalent/field testing of attenuated tetra underway now
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what are five mosq elimination breeding techniques
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1 cover water containers
2septic tanks and soak-away pits - seal |
