Dengue hemorrhagic fever

Dengue hemorrhagic fever

1. DENGUE & DENGUE
HEMORRHAGIC FEVER
DR.I.SELVARAJ, IRMS
Sr.D.M.O (Selction Grade), INDIAN RAILWAYS
B.SC.,M.B.B.S.,(M.D Community Medicine)., D.P.H., D.I.H., PGCH&FW (NIHFW, New Delhi)

2. Epidemiology
•In India first outbreak of dengue was recorded in 1812
•A double peak hemorrhagic fever epidemic occurred in India for the
first time in Calcutta between July 1963 & March 1964
•In New Delhi, outbreaks of dengue fever reported in 1967,1970,1982,
&1996

3. BURDEN OF DISEASE IN S.E.ASIA
•CATEGORY-A (INDONESIA,MYANMAR,AND
THAILAND)
•CATEGORY-B
(INDIA,BANGALADESH,MALDIVES,AND SRILANKA)
•CATEGORY-C (BHUTAN, NEPAL)
•CTEGORY-D (DPR KOREA)

4. Dengue Virus
1.Causesdengueanddenguehemorrhagicfever
2.Itisanarbovirus
3.Transmittedbymosquitoes
4.Composedofsingle-strandedRNA
5.Has4serotypes(DEN-1,2,3,4)

5. Dengue Virus
•Each serotype provides specific lifetime immunity,
and short-term cross-immunity
•Allserotypescancausesevereandfataldisease
•Geneticvariationwithinserotypes
•Somegeneticvariantswithineachserotypeappear
tobemorevirulentorhavegreaterepidemicpotential

7. The most common epidemic vector of dengue in the world is
theAedes aegyptimosquito. It can be identified by the white
bandsor scale patternson its legs and thorax.

9. Aedes aegypti
•Denguetransmittedbyinfectedfemale
mosquito
•Primarilyadaytimefeeder
•Livesaroundhumanhabitation
•Layseggsandproduceslarvae
preferentiallyinartificialcontainers

10. ClinicalCharacteristicsofDengueFever
•Fever
•Headache
•Muscleandjointpain
•Nausea/vomiting
•Rash
•Hemorrhagicmanifestations
Patients may also report other symptoms, such as
itching and aberrationsin the sense of taste,
particularly a metallic taste.In addition, there have
been reports ofsevere depressionafter the acute
phase of the illness.

11. 1.Thevirusisinoculatedinto
humanswiththemosquito
saliva.
2.Theviruslocalizesand
replicatesinvarioustarget
organs,forexample,local
lymphnodesandtheliver.
3.Thevirusisthenreleased
fromthesetissuesand
spreadsthroughthebloodto
infectwhitebloodcellsand
otherlymphatictissues.
4.Thevirusisthenreleased
fromthesetissuesand
circulatesintheblood.

12. 5.Themosquitoingestsbloodcontainingthevirus.
6.Thevirusreplicatesinthemosquitomidgut,theovaries,
nervetissueandfatbody.Itthenescapesintothebody
cavity,andlaterinfectsthesalivaryglands.
7.Thevirusreplicatesinthesalivaryglandsandwhenthe
mosquitobitesanotherhuman,thecyclecontinues.

13. ThetransmissioncycleofdenguevirusbythemosquitoAedesaegyptibegins
withadengue-infectedperson.Thispersonwillhaveviruscirculatinginthe
blood—aviremiathatlastsforaboutfivedays.Duringtheviremicperiod,an
uninfectedfemaleAedesaegyptimosquitobitesthepersonandingestsblood
thatcontainsdenguevirus.Althoughthereissomeevidenceoftransovarial
transmissionofdenguevirusinAedesaegypti,usuallymosquitoesareonly
infectedbybitingaviremicperson.
Then,withinthemosquito,thevirusreplicatesduringanextrinsicincubation
periodofeighttotwelvedays.
Themosquitothenbitesasusceptiblepersonandtransmitsthevirustohimor
her,aswellastoeveryothersusceptiblepersonthemosquitobitesfortherestof
itslifetime.
Thevirusthenreplicatesinthesecondpersonandproducessymptoms.The
symptomsbegintoappearanaverageoffourtosevendaysafterthemosquito
bite—thisistheintrinsicincubationperiod,withinhumans.Whiletheintrinsic
incubationperiodaveragesfromfourtosevendays,itcanrangefromthreeto14
days.
Theviremiabeginsslightlybeforetheonsetofsymptoms.Symptomscausedby
dengueinfectionmaylastthreeto10days,withanaverageoffivedays,afterthe
onsetofsymptoms—sotheillnesspersistsseveraldaysaftertheviremiahas
ended.

15. Thereareactuallyfourdengueclinical
syndromes:
1.Undifferentiatedfever;
2.Classicdenguefever;
3.Denguehemorrhagicfever,orDHF;and
4.Dengueshocksyndrome,orDSS.
Dengueshocksyndromeisactuallyasevere
formofDHF.

16. Clinical Case Definition for Dengue Fever
ClassicalDenguefeverorBreakbonefeverisanacutefebrile
viraldiseasefrequentlypresentingwithheadaches,boneorjoint
pain,muscularpains,rash,andleucopenia
Clinical Case Definition for Dengue Hemorrhagic Fever
4NecessaryCriteria:
1.Fever,orrecenthistoryofacutefever
2.Hemorrhagicmanifestations
3.Lowplateletcount(100,000/mm3orless)
4.Objectiveevidenceof“leakycapillaries:”
•elevatedhematocrit(20%ormoreoverbaseline)
•lowalbumin
•pleuralorothereffusions

17. ClinicalCaseDefinitionforDengueShockSyndrome
•4criteriaforDHF
+
•Evidenceofcirculatoryfailuremanifestedindirectlyby
allofthefollowing:
•Rapidandweakpulse
•Narrowpulsepressure(<20mmHg)OR
hypotensionforage
•Cold,clammyskinandalteredmentalstatus
•Frankshockisdirectevidenceofcirculatoryfailure

18. HemorrhagicManifestationsofDengue
•Skinhemorrhages:
petechiae,purpura,ecchymoses
•Gingivalbleeding
•Nasalbleeding
•Gastrointestinalbleeding:
Hematemesis,melena,hematochezia
•Hematuria
•Increasedmenstrualflow

19. Signs and Symptoms of Encephalitis/Encephalopathy
Associated with Acute Dengue Infection
•Decreased level of consciousness:
lethargy, confusion, coma
•Seizures
•Nuchal rigidity
•Paresis

20. Four Grades of DHF
Grade1
Feverandnonspecificconstitutionalsymptoms
Positivetourniquettestisonlyhemorrhagic
manifestation
Grade2
Grade1manifestations+spontaneousbleeding
Grade3
Signsofcirculatoryfailure(rapid/weakpulse,
narrow pulsepressure,hypotension,
cold/clammyskin)
Grade4
Profoundshock(undetectablepulseandBP)

21. DangerSignsinDengueHemorrhagic
Fever
•Abdominalpain-intenseandsustained
•Persistentvomiting
•Abruptchangefromfevertohypothermia,
withsweatingandprostration
•Restlessnessorsomnolence
*All of these are signs of impending shock and
should alert clinicians that the patient needs close
observation and fluids.

23. Thisthermometerillustratesthedevelopmentsintheillnessthatare
progressivewarningsignsthatDSSmayoccur.
Theinitialevaluationismadebydetermininghowmanydayshavepassed
sincetheonsetofsymptoms.
MostpatientswhodevelopDSSdoso3-6daysafteronsetofsymptoms.
Therefore,ifapatientissevendaysintotheillness,itislikelythattheworst
isover.
Ifthefevergoesbetweenthreeandsixdaysafterthesymptomsbegan,thisis
awarningsignalthatthepatientmustbecloselyobserved,asshockoften
occursatoraroundthedisappearanceoffever.
Otherearlywarningsignstobealertforincludeadropinplatelets,an
increaseinhematocrit,orothersignsofplasmaleakage.
Ifyoudocumenthemoconcentrationandthrombocytopeniaandothersigns
ofDHFandthepatientmeetsthecriteriaforDHF,theprognosisandthe
patient'sriskcategoryhavechanged.Thoughdenguefeverdoesnotoften
causefatalities,agreaterproportionofDHFcasesarefatal.
Thenextconcernwouldbeobservationofthedangersigns—severe
abdominalpain,changeinmentalstatus,vomitingandabruptchangefrom
fevertohypothermia.TheseoftenheraldtheonsetofDSS.
Thegoaloftreatmentistopreventshock.Theplasmaleakagesyndromeis
self-limited.Ifyoucansupportthepatientthroughtheplasmaleakagephase
andprovidesufficientfluidstopreventshock,theillnesswillresolveitself.

25. Purpose of Control
•Reducefemalevectordensitytoalevel
belowwhichepidemicvectortransmission
willnotoccur
•Basedontheassumptionthateliminatingor
reducingthenumberoflarvalhabitatsinthe
domesticenvironmentwillcontrolthevector
•Theminimumvectordensitytoprevent
epidemictransmission

29. LABORATORY CRITERIA
•ISOLATION OF DENQUE VIRUS
•INCREASED IgM OR IgM ANTIBODIES TITRES
•DENQUE ANTIGEN DETECTION BY
IMMUNOHISTOCHEMISTRY,IMMUNOFLUROSCENCE,ELISA
•PCR
•LEUCOPENIA,THROMPOCYTOPENIA

31. Vector Control Methods:
BiologicalandEnvironmentalControl
•Biologicalcontrol
•Largelyexperimental
•Option:placefishincontainerstoeatlarvae
•Environmentalcontrol
•Eliminationoflarvalhabitats
•Mostlikelymethodtobeeffectiveinthelongterm

32. VectorControlMethods:
ChemicalControl:
•Larvicidesmaybeusedtokillimmatureaquatic
stages
•Ultra-lowvolumefumigationagainstadult
mosquitoes
•Mosquitoesmayhaveresistancetocommercial
aerosolsprays

33. BIOLOGICALCONTROLmethodsarenotwidelyusedandareprimarily
experimental.Oneoptioninwhichbiologicalcontrolisoftenused,
however,istheplacementofsmallfishthateatmosquitolarvaeincertain
containers,suchasdecorativefountainsor55-gallondrums.Recently,a
fewcountrieshavealsoreportedsuccessincontrollinglarvaewith
copepods,smallinvertebratecrustaceansthatfeedonfirst-andsecond-
stagemosquitolarvae.
ENVIRONMENTAL CONTROL involveseliminatingorcontrollingthe
larvalhabitatswherethemosquitolayshereggsandtheimmature
mosquitoesdevelop.Thisincludesemptyingwaterfromcontainersor
coveringcontainersthatarebeingused,cleanupcampaignstodispose
ofcontainersthatarenotbeingused,andimprovingwatersuppliesso
thatthereislessneedtostorewaterincontainers.Sincechemical
controlisgenerallyrestrictedtocontainersthatcannototherwisebe
eliminatedormanaged,andbiologicalcontrolisstilllargelyexperimental,
environmentalmethodsarelikelytobethemosteffectiveforlong-term
controlofAedesaegypti.

34. Larvicidinginvolvesplacingchemicalsintocontainersthatcannoteasilybe
eliminatedtokillthemosquitolarvae.
Ultra-lowvolume,orULVsprayingofinsecticidesiswidelypracticedtokill
adultmosquitoes.
ULVsprayingusesmachinesthatproduceverysmallparticlesofinsecticide,
whicharecarriedbywindcurrents.
Typically,ULVmachinesareeithermountedontrucksorareportable
machinesthatcanbecarriedbyfieldworkers.
Theinsecticideparticlesmustcomeincontactwiththemosquitotokillit.
Unfortunately,theAedesaegyptimosquitotendstoresideinsidehouses,
oftenrestinginsecludedlocationssuchasclosetsthatarenoteasily
penetrablebytheinsecticidespray.
Thus,ULVsprayingfromvehiclesisgenerallyineffective,killingveryfew
Aedesaegyptimosquitoes.
Themethodis,therefore,expensiveandineffective.
Commercialaerosolspraystokillthemosquitoesfoundindoorsareuseful,
but"knockdownresistance"mayoccurinsomelocations.
Individualhouseholdersmaynotethatsprayinsecticidehasonlya
temporaryeffect,knockingdownorparalyzingmosquitoesthatlaterrecover
andflyaway.
Insuchcases,thesprayedmosquitoesmustalsobesquashedtoprevent
theirrecovery.

35. Althoughthegoalofdiseasecontrolistopreventepidemic
transmission,ifanepidemicdoesoccur,waystominimizeits
impactinclude:
•Teachingthemedicalcommunityhowtodiagnoseandmanage
dengueanddenguehemorrhagicfever(DHF),sotheyarebetter
preparedtoeffectivelymanageandtreatlargenumbersofcases.
MortalityfromDHFwillthusbeminimized.
•Implementinganemergencycontingencyplantoanticipatethe
logisticalissuesofhospitalizinglargenumbersofpatientsandto
outlinemeasuresforcommunity-widevectorcontrolactivities.
Suchplansshouldbepreparedwiththeparticipationofallparties
andagenciesinvolved,andshouldbereadyforimplementation
priortotheemergenceofanepidemic.
•Educatingthegeneralpublictoencourageandenablethemto
carryoutvectorcontrolintheirhomesandneighborhoods.

36. ProgramstoMinimizetheImpactofEpidemics
•Educationofthemedicalcommunity
•Implementationofemergencycontingencyplan
•Educationofthegeneralpopulation

38. THANK YOU
Reference:
1.http://www.who.int/ctd/docs/dengue.pdf
2.http://www.cdc.gov/
3.http://www.cdc.gov/ncidod/index.htm
4.SUPERCOURSE