Dengue is an arbovirus transmitted by mosquitoes that causes dengue fever and dengue hemorrhagic fever. It has 4 serotypes that provide lifetime immunity to that serotype but only short term cross-immunity. Risk of severe disease is increased in secondary infections with a different serotype due to antibody-dependent enhancement. The disease pathogenesis may involve antibodies from a previous infection forming complexes with a new infecting virus serotype, increasing virus replication in monocytes and leading to increased vascular permeability and hemorrhagic manifestations. Diagnosis involves considering travel history, signs of bleeding or increased vascular permeability, and low platelet count.

2. DengueDengue
What it is all about?What it is all about?
Dr. Naghman BashirDr. Naghman Bashir
FCPS; MRCP (UK)FCPS; MRCP (UK)

3. Ki Dengue popeKi Dengue pope
Kea Dengay pepayKea Dengay pepay
Creepy fever due to evil spiritsCreepy fever due to evil spirits
First reported in 1879First reported in 1879

4. Virus, Vector andVirus, Vector and
TransmissionTransmission

5. Dengue VirusDengue Virus
 Causes dengue and dengue hemorrhagic feverCauses dengue and dengue hemorrhagic fever
 Is an arbovirusIs an arbovirus
 Transmitted by mosquitoesTransmitted by mosquitoes
 Composed of single-stranded RNAComposed of single-stranded RNA
 Has 4 serotypes (DEN-1, 2, 3, 4)Has 4 serotypes (DEN-1, 2, 3, 4)

6. Dengue VirusesDengue Viruses
 Each serotype provides specific lifetimeEach serotype provides specific lifetime
immunity, and short-term cross-immunityimmunity, and short-term cross-immunity
 All serotypes can cause severe and fatal diseaseAll serotypes can cause severe and fatal disease
 Genetic variation within serotypesGenetic variation within serotypes
 Some genetic variants within each serotypeSome genetic variants within each serotype
appear to be more virulent or have greaterappear to be more virulent or have greater
epidemic potentialepidemic potential

8. Trouble AheadTrouble Ahead
 2.5 billion people at risk world-wide2.5 billion people at risk world-wide
 In the Americas, 50-fold increase in reportedIn the Americas, 50-fold increase in reported
cases of DHF (1989-1993 compared to 1984-cases of DHF (1989-1993 compared to 1984-
1988)*1988)*
 Widespread abundance ofWidespread abundance of Aedes aegyptiAedes aegypti in at-riskin at-risk
areasareas
* Organization of American States,
Human Health in the Americas, 1996

9. Aedes aegyptiAedes aegypti
 Dengue transmitted by infected femaleDengue transmitted by infected female
mosquitomosquito
 Primarily a daytime feederPrimarily a daytime feeder
 Lives around human habitationLives around human habitation
 Lays eggs and produces larvae preferentially inLays eggs and produces larvae preferentially in
artificial containersartificial containers

10. Aedes aegyptiAedes aegypti MosquitoMosquito

11. Transmission of Dengue VirusTransmission of Dengue Virus
byby Aedes aegyptiAedes aegypti
Viremia Viremia
Extrinsic
incubation
period
DAYS
0 5 8 12 16 20 24 28
Human #1 Human #2
Illness
Mosquito feeds /
acquires virus
Mosquito refeeds /
transmits virus
Intrinsic
incubation
period
Illness

12. Replication and TransmissionReplication and Transmission
of Dengue Virus (Part 1)of Dengue Virus (Part 1)
1. Virus transmitted
to human in mosquito
saliva
2. Virus replicates
in target organs
3. Virus infects white
blood cells and
lymphatic tissues
4. Virus released and
circulates in blood
3
4
1
2

13. Replication and TransmissionReplication and Transmission
of Dengue Virus (Part 2)of Dengue Virus (Part 2)
5. Second mosquito
ingests virus with blood
6. Virus replicates
in mosquito midgut
and other organs,
infects salivary
glands
7. Virus replicates
in salivary glands
6
7
5

14. Clinical ManifestationsClinical Manifestations
of Dengue and Dengueof Dengue and Dengue
Hemorrhagic FeverHemorrhagic Fever

15. Dengue Clinical SyndromesDengue Clinical Syndromes
75%75%

16. Clinical CharacteristicsClinical Characteristics
of Dengue Feverof Dengue Fever
 FeverFever
 HeadacheHeadache
 Muscle and joint painMuscle and joint pain
 Nausea/vomitingNausea/vomiting
 RashRash
 Hemorrhagic manifestationsHemorrhagic manifestations

17. Signs and Symptoms ofSigns and Symptoms of
Encephalitis/EncephalopathyEncephalitis/Encephalopathy
Associated with Acute DengueAssociated with Acute Dengue
InfectionInfection
 Decreased level of consciousness:Decreased level of consciousness:
lethargy, confusion, comalethargy, confusion, coma
 SeizuresSeizures
 Nuchal rigidityNuchal rigidity
 ParesisParesis

18. Hemorrhagic ManifestationsHemorrhagic Manifestations
of Dengueof Dengue
 Skin hemorrhages: petechiae, purpura,Skin hemorrhages: petechiae, purpura,
ecchymosesecchymoses
 Gingival bleedingGingival bleeding
 Nasal bleedingNasal bleeding
 Gastro-intestinal bleeding:Gastro-intestinal bleeding:
hematemesis, melena, hematocheziahematemesis, melena, hematochezia
 HematuriaHematuria
 Increased menstrual flowIncreased menstrual flow

19. Temperature, Virus Positivity andTemperature, Virus Positivity and
Anti-Dengue IgM , by Fever DayAnti-Dengue IgM , by Fever Day
Dengue IgMMean Max. Temperature Virus
Adapted from Figure 1 in Vaughn et al., J Infect Dis, 1997; 176:322-30.
0
20
40
60
80
100
PercentVirusPositive
7
39.5
39.0
38.5
38.0
37.5
37.0
Temperature(degreesCelsius)
Fever Day
1 2 3 4 5 6 8 9 10 11
DengueIgM(EIAunits)
300
150
0
75
225

20. PetechiaePetechiae

21. Tourniquet TestTourniquet Test
 Inflate blood pressure cuff to a pointInflate blood pressure cuff to a point
midway between systolic and diastolicmidway between systolic and diastolic
pressure for 5 minutespressure for 5 minutes
 Positive test: 20 or more petechiae per 1Positive test: 20 or more petechiae per 1
inchinch22
(6.25 cm(6.25 cm22
))
Pan American Health Organization: Dengue and Dengue
Hemorrhagic Fever: Guidelines for Prevention and
Control. PAHO: Washington, D.C., 1994: 12.

22. Positive Tourniquet TestPositive Tourniquet Test

23. Clinical Case Definition forClinical Case Definition for
Dengue Hemorrhagic FeverDengue Hemorrhagic Fever
 Fever, or recent history of acute feverFever, or recent history of acute fever
 Hemorrhagic manifestationsHemorrhagic manifestations
 Low platelet count (100,000/mmLow platelet count (100,000/mm33
or less)or less)
 Objective evidence of “leaky capillaries:”Objective evidence of “leaky capillaries:”
 elevated hematocrit (20% or more overelevated hematocrit (20% or more over
baseline)baseline)
 low albuminlow albumin
 pleural or other effusionspleural or other effusions
4 Necessary Criteria:4 Necessary Criteria:

24. Clinical Case Definition forClinical Case Definition for
Dengue Shock SyndromeDengue Shock Syndrome
 4 criteria for DHF4 criteria for DHF
 Evidence of circulatory failure manifested indirectly byEvidence of circulatory failure manifested indirectly by
all of the following:all of the following:
 Rapid and weak pulseRapid and weak pulse
 Narrow pulse pressure (Narrow pulse pressure (≤ 20 mm Hg)20 mm Hg) OROR
hypotension for agehypotension for age
 Cold, clammy skin and altered mental statusCold, clammy skin and altered mental status
 Frank shock is direct evidence of circulatory failureFrank shock is direct evidence of circulatory failure

25. Four Grades of DHFFour Grades of DHF
 Grade 1Grade 1
 Fever and nonspecific constitutional symptomsFever and nonspecific constitutional symptoms
 Positive tourniquet test is only hemorrhagicPositive tourniquet test is only hemorrhagic
manifestationmanifestation
 Grade 2Grade 2
 Grade 1 manifestations + spontaneous bleedingGrade 1 manifestations + spontaneous bleeding
 Grade 3Grade 3
 Signs of circulatory failure (rapid/weak pulse, narrowSigns of circulatory failure (rapid/weak pulse, narrow
pulse pressure, hypotension, cold/clammy skin)pulse pressure, hypotension, cold/clammy skin)
 Grade 4Grade 4
 Profound shock (undetectable pulse and BP)Profound shock (undetectable pulse and BP)

26. Danger Signs inDanger Signs in
Dengue Hemorrhagic FeverDengue Hemorrhagic Fever
 Abdominal pain - intense and sustainedAbdominal pain - intense and sustained
 Persistent vomitingPersistent vomiting
 Abrupt change from fever to hypothermia,Abrupt change from fever to hypothermia,
with sweating and prostrationwith sweating and prostration
 Restlessness or somnolenceRestlessness or somnolence
Martínez Torres E. Salud Pública Mex 37 (supl):29-44, 1995.

27. Warning Signs for DengueWarning Signs for Dengue
ShockShock
When Patients Develop
DSS:
• 3 to 6 days after onset of
When Patients Develop
DSS:
• 3 to 6 days after onset of
Initial Warning Signals:
• Disappearance of fever
• Drop in platelets
• Increase in hematocrit
Initial Warning Signals:
• Disappearance of fever
• Drop in platelets
• Increase in hematocrit
Alarm Signals:
• Severe abdominal pain
• Prolonged vomiting
• Abrupt change from fever
to
hypothermia
• Change in level of
consciousness (irritability
or
Alarm Signals:
• Severe abdominal pain
• Prolonged vomiting
• Abrupt change from fever
to
hypothermia
• Change in level of
consciousness (irritability
or
somnolence)
Four Criteria for DHF:
• Fever
• Hemorrhagic
manifestations
• Excessive capillary
permeability
• ≤ 100,000/mm3
platelets
Four Criteria for DHF:
• Fever
• Hemorrhagic
manifestations
• Excessive capillary
permeability
• ≤ 100,000/mm3
platelets

28. Clinical Evaluation in DengueClinical Evaluation in Dengue
FeverFever
 Blood pressureBlood pressure
 Evidence of bleeding in skin or other sitesEvidence of bleeding in skin or other sites
 Hydration statusHydration status
 Evidence of increased vascularEvidence of increased vascular
permeability-- pleural effusions, ascitespermeability-- pleural effusions, ascites
 Tourniquet testTourniquet test

29. Disease PathogenesisDisease Pathogenesis

30. Risk Factors Reported for DHFRisk Factors Reported for DHF
 Virus strainVirus strain
 Pre-existing anti-dengue antibodyPre-existing anti-dengue antibody
 previous infectionprevious infection
 maternal antibodies in infantsmaternal antibodies in infants
 Host geneticsHost genetics
 AgeAge

31. Risk Factors for DHFRisk Factors for DHF
(continued)(continued)
 Higher risk in secondary infectionsHigher risk in secondary infections
 Higher risk in locations with two or moreHigher risk in locations with two or more
serotypes circulating simultaneously at highserotypes circulating simultaneously at high
levels (hyperendemic transmission)levels (hyperendemic transmission)

32. Increased Probability of DHFIncreased Probability of DHF
Hyperendemicity
Increased circulation
of viruses
Increased probability
of secondary infection
Increased probability of
occurrence of virulent strains
Increased probability of
immune enhancement
Increased probability of DHF
Gubler & Trent, 1994

33. Neutralizing antibody to Dengue 1 virus
1
1
Dengue 1 virus1
Homologous Antibodies FormHomologous Antibodies Form
Non-infectious ComplexesNon-infectious Complexes
Non-neutralizing
antibody
1
1 Complex formed by neutralizing antibody
and virus

34. Hypothesis on PathogenesisHypothesis on Pathogenesis
of DHF (Part 2)of DHF (Part 2)
 In a subsequent infection, the pre-In a subsequent infection, the pre-
existingexisting heterologousheterologous antibodies formantibodies form
complexes with the new infecting viruscomplexes with the new infecting virus
serotype, but do not neutralize the newserotype, but do not neutralize the new
virusvirus

35. Hypothesis on PathogenesisHypothesis on Pathogenesis
of DHF (Part 1)of DHF (Part 1)
 Persons who have experienced a denguePersons who have experienced a dengue
infection develop serum antibodies thatinfection develop serum antibodies that
can neutralize the dengue virus of thatcan neutralize the dengue virus of that
same (same (homologoushomologous) serotype) serotype

36. Non-neutralizing antibody to Dengue 1
virus
Dengue 2 virus
2 2
2
2
2
Heterologous AntibodiesHeterologous Antibodies
Form Infectious ComplexesForm Infectious Complexes
Complex formed by non-neutralizing
antibody and virus
2

37. Hypothesis on PathogenesisHypothesis on Pathogenesis
of DHF (Part 3)of DHF (Part 3)
 Antibody-dependent enhancementAntibody-dependent enhancement isis
the process in which certain strains ofthe process in which certain strains of
dengue virus, complexed with non-dengue virus, complexed with non-
neutralizing antibodies, can enter aneutralizing antibodies, can enter a
greater proportion of cells of thegreater proportion of cells of the
mononuclear lineage, thus increasingmononuclear lineage, thus increasing
virus productionvirus production

38. 2
2
2
2
2
22
2
2
2
Heterologous Complexes EnterHeterologous Complexes Enter
More Monocytes, Where VirusMore Monocytes, Where Virus
ReplicatesReplicates
Non-neutralizing antibody
Dengue 2 virus2
Complex formed by non-
neutralizing antibody and
Dengue 2 virus
2

39. Hypothesis on PathogenesisHypothesis on Pathogenesis
of DHF (Part 4)of DHF (Part 4)
 Infected monocytes release vasoactiveInfected monocytes release vasoactive
mediators, resulting in increased vascularmediators, resulting in increased vascular
permeability and hemorrhagic manifestationspermeability and hemorrhagic manifestations
that characterize DHF and DSSthat characterize DHF and DSS

40. 2
2
2
2
2
22
2
2
2
Heterologous Complexes EnterHeterologous Complexes Enter
More Monocytes, Where VirusMore Monocytes, Where Virus
ReplicatesReplicates
Non-neutralizing antibody
Dengue 2 virus2
Complex formed by non-
neutralizing antibody and
Dengue 2 virus
2

41. Viral Risk FactorsViral Risk Factors
for DHF Pathogenesisfor DHF Pathogenesis
 Virus strain (genotype)Virus strain (genotype)
 Epidemic potential: viremia level,Epidemic potential: viremia level,
infectivityinfectivity
 Virus serotypeVirus serotype
 DHF risk is greatest for DEN-2, followedDHF risk is greatest for DEN-2, followed
by DEN-3, DEN-4 and DEN-1by DEN-3, DEN-4 and DEN-1

42. DiagnosisDiagnosis

43. Travel HistoryTravel History
 Important for assessment of symptomaticImportant for assessment of symptomatic
patients in non-endemic areaspatients in non-endemic areas
 Determine whether the patient travelled to aDetermine whether the patient travelled to a
dengue-endemic areadengue-endemic area
 Determine when the travel occurredDetermine when the travel occurred
 If the patient developed fever more than 2 weeksIf the patient developed fever more than 2 weeks
after travel, eliminate dengue from the differentialafter travel, eliminate dengue from the differential
diagnosisdiagnosis

44. Differential Diagnosis of DengueDifferential Diagnosis of Dengue
 InfluenzaInfluenza
 MeaslesMeasles
 RubellaRubella
 MalariaMalaria
 Typhoid feverTyphoid fever
 LeptospirosisLeptospirosis
 MeningococcemiaMeningococcemia
 Rickettsial infectionsRickettsial infections
 Bacterial sepsisBacterial sepsis
 Other viral hemorrhagic feversOther viral hemorrhagic fevers

45. Laboratory TestsLaboratory Tests
in Dengue Feverin Dengue Fever
 Clinical laboratory testsClinical laboratory tests
 CBC--WBC, platelets, hematocritCBC--WBC, platelets, hematocrit
 AlbuminAlbumin
 Liver function testsLiver function tests
 Urine--check for microscopic hematuriaUrine--check for microscopic hematuria
 Dengue-specific testsDengue-specific tests
 Virus isolationVirus isolation
 SerologySerology

46. Laboratory Methods for DengueLaboratory Methods for Dengue
Diagnosis, CDC Dengue BranchDiagnosis, CDC Dengue Branch
 Virus isolation to determine serotype ofVirus isolation to determine serotype of
the infecting virusthe infecting virus
 IgM ELISA test for serologic diagnosisIgM ELISA test for serologic diagnosis

47. Virus Isolation:Virus Isolation:
Cell CultureCell Culture

48. Virus Isolation:Virus Isolation:
Cell CultureCell Culture

49. Virus Isolation:Virus Isolation:
Mosquito InoculationMosquito Inoculation

50. Virus Isolation:Virus Isolation:
Fluorescent Antibody TestFluorescent Antibody Test

51. ELISA Test forELISA Test for
Serologic DiagnosisSerologic Diagnosis

52. ELISA PlateELISA Plate

53. TreatmentTreatment

54. General RecommendationsGeneral Recommendations
for Medical Carefor Medical Care
 Epidemiologic considerationsEpidemiologic considerations
 Season of yearSeason of year
 Travel historyTravel history
 DiagnosisDiagnosis
 TreatmentTreatment
 Follow-upFollow-up

55. Outpatient TriageOutpatient Triage
 No hemorrhagic manifestations and patient isNo hemorrhagic manifestations and patient is
well-hydrated:well-hydrated: home treatmenthome treatment
 Hemorrhagic manifestations or hydrationHemorrhagic manifestations or hydration
borderline:borderline: outpatient observation center oroutpatient observation center or
hospitalizationhospitalization
 Warning signs (even without profound shock) orWarning signs (even without profound shock) or
DSS:DSS: hospitalizehospitalize

56. Patient Follow-UpPatient Follow-Up
 Patients treated at homePatients treated at home
 Instruction regarding danger signsInstruction regarding danger signs
 Consider repeat clinical evaluationConsider repeat clinical evaluation
 Patients with bleeding manifestationsPatients with bleeding manifestations
 Serial hematocrits and platelets at least dailySerial hematocrits and platelets at least daily
until temperature normal for 1 to 2 daysuntil temperature normal for 1 to 2 days
 All patientsAll patients
 If blood sample taken in first 5 days afterIf blood sample taken in first 5 days after
onset, need convalescent sample betweenonset, need convalescent sample between
days 6 - 30days 6 - 30
 All hospitalized patients need samples onAll hospitalized patients need samples on

57. Treatment of Dengue FeverTreatment of Dengue Fever
(Part 1)(Part 1)
 FluidsFluids
 RestRest
 Antipyretics (avoid aspirin and non-Antipyretics (avoid aspirin and non-
steroidal anti-inflammatory drugs)steroidal anti-inflammatory drugs)
 Monitor blood pressure, hematocrit,Monitor blood pressure, hematocrit,
platelet count, level of consciousnessplatelet count, level of consciousness

58. Mosquito BarriersMosquito Barriers
 Only needed until fever subsides, to preventOnly needed until fever subsides, to prevent
Aedes aegyptiAedes aegypti mosquitoes from biting patients andmosquitoes from biting patients and
acquiring virusacquiring virus
 Keep patient in screened sickroom or under aKeep patient in screened sickroom or under a
mosquito netmosquito net

59. Treatment of Dengue FeverTreatment of Dengue Fever
(Part 2)(Part 2)
 Continue monitoring after defervescenceContinue monitoring after defervescence
 If any doubt, provide intravenous fluids, guidedIf any doubt, provide intravenous fluids, guided
by serial hematocrits, blood pressure, and urineby serial hematocrits, blood pressure, and urine
outputoutput
 The volume of fluid needed is similar to theThe volume of fluid needed is similar to the
treatment of diarrhea with mild to moderatetreatment of diarrhea with mild to moderate
isotonic dehydration (5%-8% deficit)isotonic dehydration (5%-8% deficit)

60. Fluid for Moderate DehydrationFluid for Moderate Dehydration
(Intravenous)(Intravenous)
weight in lbs ml/lb/day weight in kgs ml/kg/day
< 15 100 < 7 220
16 - 25 75 7 - 11 165
26 - 40 60 12 - 18 132
41 - 88 40 19 - 40 88
Adapted from Guidelines for Treatment of Dengue Fever/
Dengue Haemorrhagic Fever in Small Hospitals, WHO, 1999.

61. Rehydrating Patients Over 40 kgRehydrating Patients Over 40 kg
 Volume required for rehydration isVolume required for rehydration is twicetwice
the recommended maintenancethe recommended maintenance
requirementrequirement
 Formula for calculating maintenanceFormula for calculating maintenance
volume:volume: 1500 + 20 x (weight in kg - 20)1500 + 20 x (weight in kg - 20)
 For example, maintenance volume for 55For example, maintenance volume for 55
kg patient is: 1500 + 20 x (55-20) =kg patient is: 1500 + 20 x (55-20) =
2200 ml2200 ml
 For this patient, the rehydration volumeFor this patient, the rehydration volume
would be 2 x 2200, or 4400 mlwould be 2 x 2200, or 4400 ml
Pan American Health Organization: Dengue and Dengue
Hemorrhagic Fever: Guidelines for Prevention and Control.
PAHO: Washington, D.C., 1994: 67.

62. Treatment of Dengue FeverTreatment of Dengue Fever
(Part 3)(Part 3)
 Avoid invasive procedures whenAvoid invasive procedures when
possiblepossible
 Unknown if the use of steroids,Unknown if the use of steroids,
intravenous immune globulin, orintravenous immune globulin, or
platelet transfusions to shorten theplatelet transfusions to shorten the
duration or decrease the severity ofduration or decrease the severity of
thrombocytopenia is effectivethrombocytopenia is effective
 Patients in shock may require treatmentPatients in shock may require treatment
in an intensive care unitin an intensive care unit

63. Indications for HospitalIndications for Hospital
DischargeDischarge Absence of fever for 24 hours (withoutAbsence of fever for 24 hours (without
anti-fever therapy) and return of appetiteanti-fever therapy) and return of appetite
 Visible improvement in clinical pictureVisible improvement in clinical picture
 Stable hematocritStable hematocrit
 3 days after recovery from shock3 days after recovery from shock
 PlateletsPlatelets ≥ 50,000/mm50,000/mm33
 No respiratory distress from pleuralNo respiratory distress from pleural
effusions/asciteseffusions/ascites
Pan American Health Organization: Dengue and Dengue
Hemorrhagic Fever: Guidelines for Prevention and Control.
PAHO: Washington, D.C., 1994: 69.

64. Common Misconceptions aboutCommon Misconceptions about
Dengue Hemorrhagic FeverDengue Hemorrhagic Fever
Dengue + bleeding = DHFDengue + bleeding = DHF
Need 4 WHO criteria, capillary permeabilityNeed 4 WHO criteria, capillary permeability
DHF kills only by hemorrhageDHF kills only by hemorrhage
Patient dies as a result of shockPatient dies as a result of shock
Poor management turns dengue into DHFPoor management turns dengue into DHF
Poorly managed dengue can be more severe,Poorly managed dengue can be more severe, butbut DHF is aDHF is a
distinct condition, which even well-treated patients maydistinct condition, which even well-treated patients may
developdevelop
Positive tourniquet test = DHFPositive tourniquet test = DHF
Tourniquet test is a nonspecific indicator of capillaryTourniquet test is a nonspecific indicator of capillary
fragilityfragility

65. More Common MisconceptionsMore Common Misconceptions
about Dengue Hemorrhagic Feverabout Dengue Hemorrhagic Fever
DHF is a pediatric diseaseDHF is a pediatric disease
All age groups are involved in theAll age groups are involved in the
AmericasAmericas
DHF is a problem of low incomeDHF is a problem of low income
familiesfamilies
All socioeconomic groups are affectedAll socioeconomic groups are affected
Tourists will certainly get DHF with aTourists will certainly get DHF with a
second infectionsecond infection
Tourists are at low risk to acquire DHFTourists are at low risk to acquire DHF

66. Dengue Vaccine?Dengue Vaccine?
 No licensed vaccine at presentNo licensed vaccine at present
 Effective vaccine must be tetravalentEffective vaccine must be tetravalent
 Field testing of an attenuated tetravalent vaccineField testing of an attenuated tetravalent vaccine
currently underwaycurrently underway
 Effective, safe and affordable vaccine will not beEffective, safe and affordable vaccine will not be
available in the immediate futureavailable in the immediate future

67. PreventionPrevention

68. Early Eradication CampaignsEarly Eradication Campaigns
SucceededSucceeded
 Adequate local and external funding forAdequate local and external funding for
personnel, equipment and insecticidespersonnel, equipment and insecticides
 Emphasis on source reductionEmphasis on source reduction
 Effective residual insecticideEffective residual insecticide
 Centralized, vertically-structured programs withCentralized, vertically-structured programs with
military-type organization, strict supervision,military-type organization, strict supervision,
high level of disciplinehigh level of discipline

70. Reinfestation byReinfestation by Aedes aegyptiAedes aegypti
1930s 1970 1998

71. Hemispheric Eradication ofHemispheric Eradication of
Aedes aegyptiAedes aegypti No LongerNo Longer
RealisticRealistic
 Problem greater than during previous campaignProblem greater than during previous campaign
 Insufficient resourcesInsufficient resources
 Resistance to vertical disease control programsResistance to vertical disease control programs
and use of insecticidesand use of insecticides
 Lack of effective insecticidesLack of effective insecticides
 Low priority, lack of sustainabilityLow priority, lack of sustainability

72. Lessons for FutureLessons for Future
Dengue Prevention ProgramsDengue Prevention Programs
 Efforts should focus on sustainableEfforts should focus on sustainable
environmental control rather thanenvironmental control rather than
eradicationeradication
 Control programs should be community-Control programs should be community-
based and -integrated. They cannot relybased and -integrated. They cannot rely
solely on insecticides nor require largesolely on insecticides nor require large
budgetsbudgets
 Need to promote dengue as a priorityNeed to promote dengue as a priority
among health officials and the generalamong health officials and the general
publicpublic

73. Community ApproachesCommunity Approaches
 Typically define communities geographicallyTypically define communities geographically
 More likely to be sustainableMore likely to be sustainable
 Advantages: built-in manpower, help developAdvantages: built-in manpower, help develop
resources and empower communityresources and empower community
organizationsorganizations
 Disadvantages: more difficult to organize, takeDisadvantages: more difficult to organize, take
longer to get off the groundlonger to get off the ground

74. Thank YouThank You
MerciMerci
GrazieGrazie
GraciasGracias
DankeDanke