Epidemiology, Prevention & Control

1. Dengue
Dr. Ankit Chaudhary
Resident
Community Medicine
IGMC Shimla

2. Layout
 Introduction
 Epidemiology
 Clinical Aspect
 Prevention & Control
 Surveillance
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3. Part I
(Epidemiology & Clinical Aspect)
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4. Introduction
• Chin dynasty: 265-420 AD
• Referred to as ‘Water poison’: Associated with flying insects
• INDIA
first case DF 1956- Vellore
First case DHF 1963 – Calcutta
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5. • Acute viral (arbovirus) disease: severe, flu-like illness
• Transmitted by infective bite of Aedes aegypti mosquito
• Man develops disease after 5-6 days of being bitten by an infective mosquito
• Complex disease with wide spectrum of clinical presentation
• Dengue fever is a self-limiting disease (majority)
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6. Iceberg/Pyramidal phenomenon
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DSS
DF/DHF
Asymptomatic
Dengue virus infection manifestation

7. Global Scenario
 More than 125 countries – Dengue endemic (tropical & subtropical countries)
 Pandemic began in SE Asia after WW II; Several epidemics since 1980s
 Distribution comparable to malaria
 ≈390 million dengue infections/year; 96 million manifest clinically
 ≈ 500,000 with severe dengue require hospitalization/year (majority children)
 ≈ 2.5% of those affected die
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8. SEA Region
Category A
Bangladesh, India, Sri Lanka,
Indonesia
Major public health problem
Leading cause of
hospitalization & death among
children
Hyperendemicity with all 4
types
Spreading to rural areas
Category B
Bhutan, Nepal
Endemicity uncertain
Category C
South Korea
No evidence of endemicity
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9. 8/20/2018
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10. Dengue cases notified to WHO
1990–2015
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11. National Scenario
 First outbreak recorded in 1812
 A double peak DHF epidemic occurred in Calcutta b/w July 1963 & March 1964
 New Delhi: outbreaks of dengue in 1967, 1970, 1982, 1996, 2005, 2010, 2015
 Rapid urbanization, lifestyle changes, poor water management
 Cases peak after monsoon, In Gujarat & South India – perennial
 Endemic in 31 states/UT, CFR 0.65% 8/20/2018
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12. Dengue/DHF Distribution in India
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NVBDCP ,INDIA
Prevalent throughout
India in most of
metropolitan cities &
towns
Outbreaks have also
been reported from rural
areas of Haryana,
Maharashtra & Karnataka

13. Dengue/DHF situation in India
(Dengue cases & deaths since 2015)
Year Cases Deaths
2015 99913 220
2016 129166 245
2017 188401 325
2018 (till 22nd July 2018) 14233 30
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Source: NVBDCP India

14. Himachal scenario
Year Cases Deaths
2015 19 01
2016 322 00
2017 452 00
2018
(till
22nd
July
2018)
220 00
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Sentinel Surveillance Hospitals
Indira Gandhi Medical College, Shimla
Dr. Rajendra Prasad Medical College, Tanda
DH, Bilaspur
DH, Mandi
CHC, Nalagarh, Solan

15. Epidemiology
Agent
 ssRNA virus in family Flaviviridae (50 nm)
 4 Dengue serotypes, DEN 1/2/3/4
 Antigenically similar & cross protection is only for few months
 Infection with any one serotype confers lifelong immunity to virus serotype
 1st infection sensitizes patient
 2nd infection with different serotype: immunological catastrophe
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16. Vector (Female Mosquito)
 A. aegypti: a small (5mm), black mosquito with white stripes (Urban Areas)
 High vectorial competency
 Multiple cases & clustering of cases
 Highly domestic
 Strong anthrophilic
 Nervous feeder
 Discordant species
 A. albopictus: aggressive feeder, concordant species (Southern India) 8/20/2018
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17. Life cycle of Aedes
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18.  Feeding Habit: Day biter & Bites repeatedly
 Resting Habit
Rests in domestic & peri-domestic areas
Dark corners, hanging objects like clothes/umbrella, or under furniture
 Breeding Habits
 Any containers having even a small quantity of water
Eggs of Aedes aegypti can live without water for more than one year
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19. Favoured Breeding Sites
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20. Host
 Man is main reservoir of virus; Monkey is jungle reservoir in Malaysia & Africa
 Both sexes, All Age groups
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21. Mode of Transmission
 Transmitted from human to human by mosquito bite
 Mosquito remains infective for life
 Trans-ovarian transmission
 Infected person can’t spread infection
 But can be a source of virus for mosquitoes for 6 days
 Incubation period: 3-10 days (commonly 5-6 days)
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22. Environment
 Distinct seasonal pattern with rainy season
 Breed in artificial collections of water: discarded flower pots, old drums, water containers
 Endophagic/endophilic
 Lifespan influenced by temperature (16-30 degree C) & humidity (60-80%)
 Increased temperature: increased transmission 8/20/2018
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23. Risk Factors
Construction activities
 Water storage practice
Population movement
Heavy rainfall
Vector abundance 8/20/2018
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24. Factors for dengue epidemic
 Strain of virus influencing magnitude & duration of viraemia
 Vectorial capacity of vector
 Susceptibility of human population (genetic & immune)
 Introduction of virus into receptive community
 Severity of DHF: DENV1/2 DENV3/2 DENV4/2
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25. Asymptomatic infection Symptomatic infection
Undifferentiated fever Dengue fever Dengue haemorrhagic
fever
Dengue shock
syndrome
Dengue virus infection
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26. Classic Dengue
 Acute febrile illness with headache, retro-orbital pain, myalgia, arthralgia
 “Break-bone fever”, High fever 5-7 days, Second fever for 1-2 days in 5% patients
 Followed by marked fatigue days to weeks
 Classic dengue 15-60% of infections
 Nausea, vomiting, diarrhea (30%), Macular or maculopapular rash (50%)
 Respiratory symptoms: cough, sore throat (30%)
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27. Dengue fever
Probable Diagnosis
Acute febrile illness with 2 or more of following
 Headache/retro-orbital pain /myalgia
/arthralgia/rash/hemorragic/leucopenia/thro
mbocytopenia/rising PCV
Plus at least one of following
 Supporting serology on single serum sample
(comparable IgG or +ve IgM)
 Occurrence at same location & time as
confirmed case of DF
Confirmed Diagnosis
Probable case with at least one of following
 Isolation of DV from serum/CSF/autopsy
 4X or more increase in serum IgG or IgM
 Detection of DV or antigen in tissue, serum,
CSF by immunohisto or ELISA
 Detection of DV genomic sequence by RT-PCR
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28. Dengue Hemorrhagic Fever
WHO definition
 Thrombocytopenia (<100,000)
 Fever 2-7 days
 Hemorrhagic manifestations with a
positive tourniquet test
 Hemoconcentration or evidence of
plasma leakage
In secondary infections after actively/passively
acquired immunity to a different viral serotype
2-4% of infections result in severe disease
Mortality is 10-20% if untreated, but decreases
to <1% if adequately treated
Plasma leakage may progress to DSS
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29. Signs & Symptoms of DHF & Shock Syndrome
 Symptoms similar to dengue fever
 Severe continuous stomach pains, Skin becomes pale, cold or clammy
 Bleeding from nose, mouth & gums and skin rashes, Frequent vomiting with/without blood
 Sleepiness and restlessness, Patient feels thirsty and mouth becomes dry
 Rapid weak pulse, Difficulty in breathing
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30. WHO classification & Grading of severity
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31. Period of Communicability
 Infected person with Dengue becomes infective to mosquitoes 6 to 12 hours
before the onset of disease & remains so upto 3 to 5 days
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32. Laboratory Diagnosis of Dengue
 Virus isolation (sample within 6 days)
 Viral Nucleic acid detection (RT-PCR)
 Viral antigen detection: ELISA/Dot blot against EM/NS1 (don’t differentiate serotypes)
 Immunological/Seological Tests
 Haemagglutination inhibition (HI) test
 Compliment Fixation Test (CFT)
 Neutralization test (NT)
 IgM-capture Enzyme-Linked Immunosorbent Assay (MAC-ELISA) recommended
 IgG-ELISA
 Rapid Diagnostic tests (NS 1)
 Hematological Parameters: Platelet count/hematocrit
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33. Dengue Diagnostics & Sample Characteristics
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34. Management
 Early reporting of the suspected dengue fever
 No specific therapy, Mx of Dengue fever is symptomatic & supportive
Bed rest is advisable during the acute phase
Use cold sponging to keep temperature below 39 C
Antipyretics may be used to lower the body temperature
 Aspirin/NSAID should be avoided (gastritis, vomiting, acidosis, platelet dysfunction, Reye’s)
 In dengue shock syndrome, the following treatment is recommended
 Replacement of plasma losses
 Correction of electrolyte and metabolic disturbances
 Blood transfusion 8/20/2018
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35. Indications
Red cell transfusion
 >10% of total blood volume
 Refractory shock despite fluid
administration & declining PCV
 If fluid overload; packed cells
Platelet transfusion
 Prophylactically given if < 10000/cu. mm
 Prolonged shock with coagulopathy &
abnormal coagulogram
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36. Thank you…!!!
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37. Dengue
Part II
(Prevention & Control)
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38. Prevention & Control
(Efforts at all levels, including individuals, the family, the community and the
Government, contribute to preventing the spread of the epidemic)
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39. At Household level
 Kill adult mosquitoes: commercially available safe aerosols (Pyrethroid-based)
 Spray bedrooms, closets, bathrooms & kitchens (by removing/covering all food items
properly) for a few seconds & close room for 15-20 minutes
 Timing of spray should coincide with peak biting times (early morning/late afternoon)
 Intensify efforts to reduce actual or potential larval habitats in/around houses
Use commercially available repellants during day time
Cover water containers to prevent fresh egg laying
Have infants sleep under bed nets during day/Wear protective clothing
Use tight-fitting screens/wire mesh on doors & windows
Clogged gutters & flat roofs that may have poor drainage need to be checked regularly
Ornamental water tanks/garden: larvivorous fish (e.g. Gambusia, Guppy)
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40. At Institutional level
 Students/employees should be
provided with health education on all aspects of dengue
trained on how to detect & eliminate breeding in/& around schools/homes/neighborhood
advised to wear protective clothing (full sleeves shirts & full pants during day time)
 Ornamental water tanks/garden: larvivorous fish (e.g., Gambusia, Guppy)
 Weeds/tall grasses should be cut short (shady places for resting)
 In case, water containers can’t be emptied: Temephos (1 ppm)/weekly
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41. At Community level
 Groups to supplement & reinforce efforts at household levels
 Such groups can identify commercial activities such as traders dealing in used tyres
(contributing larval habitats for vector)
 Can create awareness about dengue & seek cooperation for removal of breeding places
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42.  Community activities against larvae & adult mosquitoes can include:
Cleaning/covering water storage containers
Keeping surroundings clean & improving basic sanitation measures
Burning mosquito coils to kill/repel mosquitoes
Burning neem leaves/coconut shells/husks to repel mosquitoes & to eliminate breeding sites
Screening houses, particularly bedrooms
Cleaning weeds/tall grass to reduce available outdoor resting places for mosquitoes
Using mosquito nets to protect infants/small children from bites during the day time
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43. Action by local health authorities
(during an outbreak)
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44. Constitution of Emergency Action Committee & Rapid Action Team
Emergency Action Committee (EAC)
Should be constituted under Chairmanship of DC/MC
To co-ordinate activities aimed at emergency vector Cx measures & Mx of serious cases
Administrators, epidemiologists, entomologists, clinicians, laboratory specialists, school
health officers, health educators & representatives of other related sectors
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45. Functions
 To take all administrative actions & coordinate activities aimed at Mx of serious cases in all
medical care centers & undertake emergency vector Cx measures
 To draw urgent plans of action & resource mobilization in r/o medicines, IVF, blood
products, insecticides, equipment & vehicles
 To liaise with inter-sectoral committees to mobilize resources from non-health sectors,
(Urban Development; MO Education, MO Information; Legal Department; Water Supply;
Waste Disposal & Information) for elimination of breeding potential of vector
 To interact with news media & NGOs for dissemination of information related to health
education & community participation
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46. Rapid Action Team (RAT)
To undertake urgent epidemiological investigations
To provide on the spot technical guidance required & logistic support
At state level: epidemiologists, entomologists and a laboratory specialist
At local levels: MO, public health officer, non-health staff, local Government staff
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47. Functions
 Undertake urgent epidemiological/entomological investigations
 Provide emergency logistical support (delivery of medical & lab supplies to HCFs)
 Provide on-the-spot Mx training for local health staff
 Supervise elimination of breeding places & application of vector Cx measures
 Carry out health education activities, Collection of serum specimens 8/20/2018
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48. Vector control Measures
 For epidemics control: vector Cx is most important strategy to interrupt or reduce transmission
 Adult mosquitoes can be controlled by chemical insecticides (Emphasis: rapid & effective source
reduction for elimination of breeding sites of vectors will achieve same results)
 Larval control is more economical & sustainable (eliminates newly-emergent adult mosquitoes)
 Chemical: ineffective in most conditions (rarely epidemic will be controlled)
 Because of visibility, people think Government is doing something (false sense of security)
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49. Space Spraying
Indoor space spraying
 Pyrethrum extract after dilution is sprayed (Flit pump or hand operated fogging machine)
 Commercial formulation (2% pyrethrum extract) is diluted with kerosene (1:19); 0.1%
pyrethrum extract ready-to-spray formulation
 1L of ready-to-spray formulation is sufficient to cover 20 households, each household
having 100 cubic metres of indoor space
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50. Advantages of Indoor pyrethrum space spray
 Non-toxic to humans and other non-target organisms at recommended dose
 Spray equipment is simple, cheap & readily available in market at affordable prices
 Householders can spray the diluted pyrethrum with ease in their own premises
 Vectors haven’t yet developed resistance to this natural product
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51. Outdoor space spraying
Ultra Low Volume (ULV) Spray
 Minimum volume of liquid insecticide is applied /unit area (maximum effectiveness)
 Most OPs in their technical form can be applied as ULV spray (presently technical malathion)
 Insecticide is broken down into small droplets of VMD of 40-80 microns
 Remain suspended for an appreciable time & driven under influence of wind
 As no diluent is used, more cost-effective than thermal fogging (doesn’t generate a visible fog)
 Equipment: portable motorized, knapsack blowers & cold aerosol generators 8/20/2018
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52. Advantages of ULV spray (Cold Fog)
 Less use of insecticide/diluent, mostly ready to use formulation
 Low fire hazard/relatively more environment-friendly
 Efficient application (finer size droplets with less volume of insecticide)
 Practically no visibility reduction due to ULV fog
 Not visible like thermal fog 8/20/2018
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53. Thermal Fogging
 Principle: Insecticide is vapourized, condenses to form a fine cloud of droplets on contact
with cooler air. Once fog comes out of machine, spreads in different directions
 Insecticide of choice: malathion/pyrethrum (↓ mammalian toxicity/biodegradable)
 Psychologically more acceptable as it generates a highly visible fog
 Equipment: Thermal fogger & mist blowers; Vehicle mounted
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54. Advantages
 Lesser insecticide in a large volume of
diluent (lesser exposure)
 Easily visible fog resulting sense of
satisfaction
Disadvantages
 Large volume organic solvent,
expensive
 Fog causes ↓ visibility & traffic
hazards
 Burning of diluent (not environment
friendly)
 ↑↑ temp. of machine operations &
use of organic solvents (highly
inflammable): risk of fire hazards
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55. Larval Control measures
 Removal, disposal, burying or burning of all unused tins, cans, jars, bottles, tyres, coconut
shells, husks & other items that can collect water
 Keeping tyres, metal boxes, discarded appliances, sinks, basins, cement tanks etc. in
industrial/commercial premises, in sheltered areas protected from rainfall
 Arranging clean up campaigns once/twice a year by local health authorities or community
leaders to remove all unusual containers & potential breeding sites
 Turning water drums & small earthen jars upside down once a week
 Periodically scrubbing inside of water containers to destroy Aedes eggs
 Regularly emptying water in flower vases in houses and offices at least once a week
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56.  Covering large volume water tanks, inlets & overflow outlets with mosquito wire mesh
 Construction of tanks with a plug at bottom to allow easy draining for weekly cleaning
 Shredding or cutting old tyres into flat pieces and disposing them properly
 Puncturing holes in tyres used for recreational purposes by children in schools & parks
 Draining water logged tree holes
 Filtering water from one container to another through cloth to trap/dislodge larvae & pupae
 Introducing larvivorous fish in water storage containers to eat mosquito larvae
 If water containers can’t be emptied, Temephos (1 ppm) should be applied on weekly basis
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57. Surveillance
 Epidemiological/entomological surveillance needs to be intensified; Reporting of fever cases
is to be monitored closely
 Active surveillance by health workers need to use case definition for cases presenting with
acute fever associated with Arthralgia/Arthritis for early Dx/Rx
 Vector surveillance (both adult & aquatic stages of mosquitoes) should be intensified; will
help in identifying areas for initiating Cx measures & assess impact
 Medical/health institutions, professional associations, private practitioners, NGOs should be
involved for fever reporting & proper case Mx 8/20/2018
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58. Epidemiological surveillance
Epidemiological surveillance requires report on following indicators:
 Suspected (clinical) cases of dengue and severe dengue
 Confirmed (laboratory-tested) cases of dengue and severe dengue
 Circulating serotypes (DEN-1,-2,-3 or -4)
 Number of deaths from dengue or severe dengue
 Number of deaths among severe dengue cases, suspected or confirmed
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59. Vector surveillance
Larval surveys
 House index (HI): %age of houses infested with larvae and/or pupae.
 Container index (CI): %age of water-holding containers infested with larvae/pupae
 Breteau index (BI): number of positive containers per 100 houses inspected
Pupae surveys
 Pupa index (PI): number of pupae per 100 houses inspected.
Adult surveys
 Estimating adult population density using ovi/sticky traps, human landing collections etc.
Aedes aegypti index
 %age of houses/premises in a limited well defined area that show actual breeding of Aedes
aegypti larvae; should be kept below 1%. In addition to this, airports and seaports should be
free of aedes aegypti breeding up to 400m from their perimeters
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60. IEC activities
 Education: mode of transmission, availability of Rx & adoption of Cx measures, activities to be
intensified to effect changes in practice of storage of water & personal protection
 Preventable disease: Encouraged to use personal protection measures (full sleeved cloths, use
of mosquito repellant & insecticide treated nets)
 Advised to cooperate during fogging & take measures for eliminating breeding places;
Community ownership to be encouraged for long term sustenance low larval/adult densities
 Special campaigns: With involvement of local newspapers, radio & TV as well outdoor publicity
like hoardings, rallies etc. IEC should be developed & widely disseminated
 Inter-personal communication (group meetings, folk media) must be optimally utilized
 Involvement of NGOs, Faith Based Organizations, Welfare Organizations, Self-Help Groups &
professional associations like IMA, NCC in schools & colleges in control activities
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61. Vaccine
 Dengvaxia (CYD-TDV): Prophylactic, Tetravalent, Live attenuated
 Indication: 9-45/9-60 years, dengue endemic areas
 Single dose/Multi-dose vial, Freeze dried, to be reconstituted (0.4% or 0.9% NaCl)
 3 s/c injections, 0.5 ml, at 6 months interval
 Shelf life: 36 months when stored b/w 2-8 deg. C
 Contraindications:
H/o severe allergic rxn to any component of dengue vaccine/after prior administration
Congenital/acquired immune deficiency impairing cell mediated immunity
Pregnant/breastfeeding women
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62. Legislative measures
 Model civic byelaws: Under this act fine/punishment is imparted, if breeding is detected
(Mumbai, Navi Mumbai, Chandigarh and Delhi Municipal Corporations)
 Building Construction Regulation Act: byelaws should be made for appropriate overhead &
under ground tanks, mosquito proof buildings for not allowing stagnation of water. In Mumbai,
prior to any construction activity, the owners/builders deposit a fee for controlling
mosquitogenic conditions at site by the Municipal Corporation
 Environmental Health Act: byelaws should be made for the proper disposal/storage of junk,
discarded tins, old tyres and other debris, which can withhold rain water
 Health Impact Assessments: Appropriate legislation should be formulated for mandatory HIA
prior to any development projects/major constructions
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63. Global Strategy for Dengue Prevention & Control
(2012-2020)
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Global threat requiring global
response (all possible partners)
Strategy: promotes co-ordination &
collaboration among multi-sectoral
partners on integrated vector Mx &
sustained Cx measures at all levels

64. Dengue Application
 ‘India Fights Dengue’ (NVBDCP/MoHFW, NHP)
 7th April 2016, Android based
 To empower Community for their involvement
and active participation in Dengue control
 Detailed information, how to prevent it, Do’s &
Don’ts, where to go for help etc.
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65. 8/20/2018
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Thank you…!!!