Dengue epidemiology

Dengue : a vector born disease

1. DENGUE
EPIDEMIOLOGY
Dr SEEMA VERMA
Department of Community medicine
PGIMS Rohtak
Haryana INDIA

2. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

3. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

4. INTRODUCTION
Most rapidly spreading mosquito-borne viral
disease in the world.
The infection causes flu-like illness,
and occasionally develops into a potentially lethal
complication –dengue shock syndrome.
Incidence of dengue has grown dramatically
around the world in recent decades.
There is under-reporting & misclassification.

5. INTRODUCTION
Before 1970, only 9 countries had experienced
severe dengue epidemics.
Disease now endemic in more than 100 countries
in the WHO regions of Africa, the Americas, the
Eastern Mediterranean, South-East Asia and the
Western Pacific.
The America, South-East Asia and Western
Pacific regions are the most seriously affected.

6. INTRODUCTION
Recent estimate –
390 million dengue infections / year.
96 million manifest clinically
The number of cases reported increased from 2.2
million in 2010 to 3.2 million in 2015.
Sharp increase in the number of cases reported in
recent years.
*World Health Organization. Dengue and severe dengue fact sheet. Geneva: WHO; 2016

7. INTRODUCTION
South-East Asia region –divided into 3 categories
•(Bangladesh, India, Indonesia, Maldives, Myanm
ar, Sri Lanka, Thailand andTimor-Leste)
•Major public healthproblem;
•Leading cause of hospitalization and death
amongchildren;
•Hyperendemicitywith all 4 serotypes circulating
in urban areas;and
•Spreading to ruralareas
A

8. INTRODUCTION
South-East Asia region –divided into 3 categories
•(Bhutan,Nepal)
•Endemicityuncertain;
•Bhutan reported first outbreak in 2004;and
•Nepal reported first indigenous case in2004.
B
•(DPR Korea)
•No evidence ofendemicity.
C

9. INTRODUCTION

10. INTRODUCTION
Dengue now endemic in all states/UTs. After
1996, outbreaks upsurge recorded in 2003, 2005,
2008, 2010, 2012 and 2013.
During 2014, more than 40,000 cases and 137
deaths reported & case fatality rate 0.33%.
In 2015, 90,000 cases and 181 deaths reported.
*DK Taneja’sHealth Policies Programmesin India; 15
th
ed. 2017

11. INTRODUCTION
In 2015, Delhi, recorded its worst outbreak since
2006 with over 15000 cases.
Disease is spreading to newer geographical areas
every year.
Outbreaks have been reported from rural areas of
Haryana, Maharashtra and Karnataka.
*DK Taneja’sHealth Policies Programmesin India; 15
th
ed. 2017

12. INTRODUCTION (CASETREND)
0
20000
40000
60000
80000
100000
120000
140000
2008200920102011201220132014201520162017
HARYANA
INDIADENGUE
CASES
YEAR
CASES TILL 8
TH
OCTOBER 2017 (NVBDCP)
129161
78691
99913
75808
40571

13. INTRODUCTION (MORTALITYTREND)
0
50
100
150
200
250
300
2008200920102011201220132014201520162017
INDIA
HARYANA
DEATHS
YEAR
DATA TILL 8
TH
OCTOBER 2017 (NVBDCP)

14. INTRODUCTION
Dengue Problem Statement: ROHTAK 2017
*Till 15
th
Oct 2017

15. INTRODUCTION
Dengue Problem Statement: Haryana & Rohtak
2017
Rohtak
Haryana0
200
400
600
800
Rohtak
Haryana
187
628
*TILL 15
TH
OCTOBER 2017
1
0

16. INTRODUCTION

17. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

18. EPIDEMIOLOGICAL DETERMINANTS
Agent
Host Environment

19. AGENT: DENGUEVIRUS
ArbovirusssRNA virus
Genus Flavivirus
Family Flaviviraede.
Four serotypes:
DENV-1, DENV-2, DENV-3 and DENV-4.
Infection with one serotype confers
life long immunity to thatvirus serotype
and only for few months to other serotypes.

20. AGENT: DENGUEVIRUS
All 4 serotypes are capable to produce DHF.
However, severity of the disease ascertained by
Serotype sequence & the strain which produces the
secondary inf
DENV-1DENV-2-500fold risk of DHF
DENV-3DENV-2-150 fold
DENV-4DENV-2-50 fold risk of DHF.

21. AGENT: DENGUEVIRUS
WHY SECOND INFECTION IS
MORE DANGEROUS??
SENSITIZATION
OF IMMUNE
SYSTEM
PATIENT
FIRST
INFECTION
SECOND INFECTION WITH
DIFFERENT SEROTYPE
IMMUNOLOGICAL
CATASTROPHY

22. VECTOR
A aegyptiis prevalent transmitter throughout India
except Kerlawhere A albopictusis main vector for transmission.

23. AEDESMOSQUITO
A small (5mm), black mosquito with white
stripes.
Adult life span:15 days,
Flight range –400 meters (average).

24. AEDESMOSQUITO
FEEDING HABITS:
Usually a Day biter,
preferably bites on the ankles and elbows.
(Peak : within 2 hours after dawn and before
sunset.)
Is strongly anthropophilic.
Known to be a nervous feeder
it bites more than one host to complete one meal.
This feeding habit results in the generation of
multiple cases and the clustering of dengue cases
in the cities.

25. AEDESMOSQUITO
Life cycle: 7 –10 days

26. ENVIRONMENTAL FACTORS
The population of Aedesaegyptifluctuates with
rainfall and water storage.
Its life span is influenced by
temperature (16
0
C -30
0
C) and humidity (60-80 %).
Even with a 2
0
increase in temperature,
The extrinsic incubation period of DENV will be
shortened
and more infected mosquitoes are available for a
longer duration.
K Park , 24
th
ed; 2017,p 262

27. ENVIRONMENTAL FACTORS
Unplanned urbanization raises the potential for
the vector to breed at high level
Rural spread of the vector is a relatively recent
occurrence with lifestyle changes coupled with
development activities, improved transport
system, deficient water management including
improperwater storage practices.

28. BREEDINGPLACES

29. ENVIRONMENTAL FACTORS
Seasonal trends of dengue cases in India 2010-
2013

30. ENVIRONMENTAL FACTORS
Seasonal trends of dengue cases in Rohtak2017
0
20
40
60
80
100
120
140
july aug sep oct
cases
cases
*TILL OCTOBER 15
TH
2017
CASES
MONTHS

31. TRANSMISSIONOFDISEASE
The Aedesmosquito becomes infective by feeding on a
patient from the day before onset to the 5th day (viraemia
stage) of illness.
After an extrinsic incubation period of 8 to 10 days, the
mosquito becomes infective, and is able to transmit the
infection.
Once the mosquito becomes infective, it remains so for
life.
The genital tract of the mosquito gets infected and
transovariantransmission of dengue virusoccur.
K.Parks.Park’sTextbook of Preventive and social medicine. Epidemiology of communicable
diseases.24
rd
edition.Jabalpurindia:M/s BanaridasBhanot;2017:page-264

32. TRANSMISSIONOFDISEASE

33. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

34. CASEDEFINITION
Suspected:
A case compatible with the clinical description.
Probable:
A case compatible with the clinical description with
one or more of the following:
Supportive serology.
Occurrence at same location and time as other
confirmed cases of dengue fever.
Confirmed:
A case compatible with the clinical description that is
laboratory confirmed.

35. D
S
S

36. CLASSIFICATION
Dengue
virus
infection
Asymtomatic
“ICEBERRG”
Symptomatic
Undifferentiated
fever{ viral
syndrome}
Denguefever
Without
haemorrhage
With unusual
haemorrhage
Dengue
haemorrhagic
fever
Unusual
manifestation/
expandeddengue
syndrome
DHF1
DHF2
DHF3
DHF4
DSS

37. CLASSICALDENGUEFEVER

38. DENGUEHAEMORRHAGIC FEVER
(DHF)
A severe form of dengue fever.
The course of dengue illness can be divided into
threephases-
febrilephase,
critical phase and
recoveryphase,

40. FEBRILEPHASE
Day 1 –4
Fever with Positive tourniquet test

41. TOURNIQUETTEST
Goal of the test:-
Toassesfragility of capillarywalls
To identifythrombocytopenia
In DHF grade 1, a positive
tourniquet test serves as the only
indicator of haemorrhagictendency
•≥20 petechiae
per1 square
inch.

42. CRITICAL/ HAEORRHAGIC PHASE
When the temperature drops to 37.5-38°C or
less, and remains below this level, usually on days 4-
7 of illness,
An increase in capillary permeability in parallel with
increasing haematocritlevels may occur.
This marks the beginning of the critical phase.
The period of clinically significant plasma leakage
usually lasts 24-48hours.

43. CRITICAL/ HAEORRHAGIC PHASE
Shock occurs when a critical volume of
plasma is lost through leakage.
It isoften preceded by warning signsof
Abdominal pain ortenderness,
Persistentvomiting,
Clinical fluidaccumulation,
Mucosalbleeding,
Lethargy,
Restlessness,
Liver enlargement more than 2 cm.and
Oliguria.

44. CRITICAL/ HAEORRHAGIC PHASE
With prolonged shock, the consequent organ
hypoperfusionresults inprogressive organ
impairment, metabolic acidosisand disseminated
intravascularcoagulation.
This in turn leads to severe haemorrhagecausing the
haematocritto decrease in severe shock. Instead of the
leukopeniausually seen during this phase of dengue, the
total white cell count may increase in patients with severe
bleeding.
In addition, severe organ impairment suchas severe
hepatitis, encephalitisor myocarditisand/or severe
bleeding mayalso develop without obvious plasma leakage
orshock.

45. RECOVERYPHASE
After critical phase, 48-72 hours of reabsorption
of extravascularfluid
Well-being, appetiteimproves
Bradycardiacommon
Hemodynamic statusimproves
GI symptomsabate
Blood counts normalize(RBC>WBC>Plt)
Diuresisoccurs
Prolongedconvalescence

46. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

47. RECOMMENDED TESTS
GOI recommends use of ELISA based antigen
detection test (NS1)for diagnosing the cases
from 1st day onwards.
Antibody detection test IgMCapture ELISA
(MAC ELISA) for diagnosing the cases after
5th day of onset of disease for confirmation of
Dengue infection

48. RECOMMENDED TESTS
NVBDCP had been using MAC-ELISA for
diagnosis of dengue infectionin the network of
Diagnostic Centers established/ identified in the
Sentinel Surveillance Hospitals (SSHs) and
Apex Referral Laboratories (ARLs) across
the country.

49. RECOMMENDED TESTS
VIRUS
NS-1
IgG (SECOND)
IgM
IgG (FIRST)

50. RAPIDTESTCOMBOKIT
Most of the studies have
shown thatdetection of
both the NS1 Antigen
and the anti-dengueIgm
together yields
satisfactory clinical
results, instead of sole
NS1 antigendetection.

51. DIAGNOSTICKITUSEDINPGIMS ROHTAK
For NS-1 Antigen detection ( <5days)

52. DIAGNOSTICKITUSEDINPGIMS ROHTAK
IgMcapture ELISA ( >5days)

53. SENTINALSURVEILLANCE HOSPITALSFORDENGUEINHARYANA2016
1 B.K. Hospital, Faridabad
2 General Hospital, Ambala
3 State Bacteriological Laboratory,Karnal
4 General Hospital, Gurgaon
5 General Hospital, Panchkula
6 Medical College, Agroha
7 Civil Hospital, Hissar
8 PGIMS,Rohtak
9 District Hospital, Kaithal
10 District Hospital, Kurukshetra
11 MukandilalHospital,YamunaNagar
12 Civil Hospital, Sonipat
13 General Hospital, Palwal
14 Civil Hospital, Bahadurgarh(Jhajjar)
15 District Hospital, Sirsa
16 District Hospital, Bhiwani
17 District Hospital, Fatehbaad
18 District Hospital, Jind
19 District Hospital, Panipat
20 Civil Hospital, MandiKhera(Mewat)
21 Civil Hospital, Narnual
22 Civil Hospital, Rewari

54. APEX REFERAL LABORATORIES
National Institute of Virology (ICMR), Pune
2. National Center for Disease Control (former NICD), Delhi
3. National Institute of Mental Health & Neuro-Sciences, Bangalore
4. Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Lucknow
5. Post-Graduate Institute of Medical Sciences(PGIMER), ICMR, Chandigarh
6. All India Institute of Medical Sciences, Delhi
7. ICMR Virus Unit, National Institute of Cholera & Enteric Diseases, Kolkata.
8. Regional Medical Research Centre, (ICMR),Dibrugarh, Assam
9. King’s Institute of Preventive Medicine (ICMR), Chennai
10. Institute of Preventive Medicine, Hyderabad
11. B J Medical College (ICMR) , Ahmedabad
12. State Public Health Laboratory, Thiruvananthapuram, Kerala
13. DefenceResearch Development and Establishment, Gwalior, Madhya Pradesh
14. NationalInstitute for Research in Tribal Health (NIRTH) (Former
RMRCT), ICMR, Jabalpur, Madhya Pradesh
15. Regional Medical Research Centre, (ICMR), Bhubaneswar, Odisha
16. Andhra Medical College, Visakhapatnam

55. MANAGEMENT OFDENGUEFEVER
MANAGED AT HOME
BED REST
COLD/TEPID SPONGING
PARACETAMOL
WARNING SIGNS SHOULD BE EXPLAINED
ADVISED TO REPORT TO HOSPITAL IF WARNING
SIGNS APPEAR

56. WARNINGSIGNS
RECURRET VOMITING
BLEEDING FROM DIFFERENT SITES:
GUMBLEEDING
BLOODINSPUTUM
BLOODINVOMITORSTOOL
INCREASEDMENSTRUALFLOW
ABDOMINAL PAIN OR DISCOMFORT
COLD CLAMY SKIN
PALPITAION BREATHLESSNESS

57. MANAGEMENT OFDHF
ALL CASES TO BE ADMITTED
ENCOURAGE ORAL FLUIDS:ORS,JUICES
START I.V. FLUIDS
PARACETAMOL
DAILY HEMATOCRIT DETERMINATION
MONITOR URINE OUTPUT, B.P. AND OTHER VITAL SIGNS
Plateletconcentrate:
iftheplateletcountis<50,000/mm
3
withbleeding.
Intheabsenceofbleeding:counts<10,000/mm
3

58. MANAGEMENT OFDSS
All of the following 6 criteria must be met before a
patient is discharged from the hospital :
2.Absence of fever for 24 hours & return of appetite
1.Visible improvement in clinical picture
4.Stable hematocrit
3.Threedays after recovery from shock
5.Platelet count greater than 50,000/mm
3
and rising
6.No respiratory distress

59. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

60. GLOBALSTRATEGYFORDENGUE
PREVENTIONANDCONTROL, 2012–2020
GOAL: To reduce the burden of dengue
OBJECTIVES: (using 2010 as the baseline).
To reduce mortality from dengue by at least
50% by 2020.
To reduce morbidityfrom dengue by at least
25% by 2020
To estimate the true burdenof dengue till
2015.
WHO (2012), Global Strategy for Dengue Prevention and Control,2012-2020.

61. EPIDEMIOLOGICAL SURVEILLANCE
Routine surveillance:
Passive
Active
Proactive surveillance:
serological surveillance designed to monitor
dengue virus transmission, especially during
inter-epidemic periods and provide information
on:
Wheretransmission is occurring,
Whatvirus serotype or serotypes are involved and
Whichtype of illness is associated with the dengue

62. EPIDEMIOLOGICAL SURVEILLANCE
Reporting:
During transmission period
(monsoon and post Monsoon reporting will be on
daily basis by email or by fax.
In nonor low transmission period
reporting will be on weekly basis.
Report of the previous week (Monday to Saturday)
should be compiled by the States and send to
NVBDCP by every Monday.

63. EPIDEMIOLOGICAL SURVEILLANCE

64. EPIDEMIOLOGICAL SURVEILLANCE
The larval indices used to determine the intensity
of dengue vector are:
House Index:
Percentage of houses positive for larvae of A aegypti
(> 10% -high risk of transmission)
BreteauIndex:
Number of positive containers for A aegyptilarvae
per 100 houses.
(> 50% -high risk of transmission)

65. ENVIRONMENTAL CONTROL
Don’tallowwatertoremainstagnant
inandaroundyourhouse.
Filltheditches.
Cleantheblockeddrains.
Emptytheroomaircoolersandflowervasescompletely
atleastonceinsevendaysandletthemdry.
Disposeoffoldcontainers,tinsandtyresetc.properly.
Keepthewatertanksandwatercontainerstightly
coveredsothatthemosquitoescannotenterthemand
startbreeding.

66. ENVIRONMENTAL CONTROL
Whereveritisnotpossibletocompletelydrainthewater
offfromroomcooler,watertanksetc.,itisadvisedtoput
abouttwotablespoons(30ml.)ofpetrolorkerosene
oilintothemforeach100litresofwater.
Thiswillpreventmosquitobreeding.
Repeatiteveryweek.
Keepthesurroundingsofyourhouseclean.
Don’tallowwildherbsetc.togrowaround
yourhouse.Theyactashidingandresting
placesformosquitoes.

67. PERSONALPROTECTIONMEASURES
Protective clothing mats
coils
Repellent sprays Insecticide treated nets
Permethrintreated clothing
(DEET)
Electric Raquete

68. CHEMICALCONTROL
LARVICIDAL
ADULTICIDAL
RESIDUAL TREATMENT
SPACE SPRAY
OUTDOOR
INDOORCOLD AEROSOL
THERMAL FOGGING
PYRETHRUM

69. INDOORSPACESPRAYING
Commercial formulation of 2% pyrethrum
(deltamethrin)extract is diluted with kerosene
in the ratio one part of 2% pyrethrum extract
with 19 parts of kerosene (volume/volume).
One liter of ‘ formulation is sufficient to cover
20 households, each household having 100
cubic meters of indoor space.

70. OUTDOORSPACESPRAYING
Usually carried out in early morning or late afternoon
For narrow roads: the spray should be directed backwards
from the vehicle.
For wide roads: the spray should be directed at a right angle
(downward) to the road.
1. Ultra Low Volume (ULV) Spray(cold fog):
MalathionTECHNICAL is the insecticide used for this
purpose.
Remain suspended in air and driven under the influence of
wind.
Since no diluentis used, the technique is more cost-
effective than thermal fogging.
But it does not generate a visible fog.

71. OUTDOORSPACESPRAYING
2. Thermal Fogging
Water based
Oil based(m/c used)
Technique is based on the principle that
insecticide is vaporized, which condenses to
form a fine cloud of droplets on contact with
cooler air when it comes out of the machine.
Insecticide of choice for fogging is
malathion/pyrethrin.

72. LARVICIDES
Cycle: 2-3rounds /year
Both internal and external walls of container should
be sprayed and up to 60cm of height.
LARVICIDES
FOR POTABLE WATER FOR NON-POTABLE WATER
TEMEPHOS (1mg/L)
METHOPRENE(1mg/l)
TEMEPHOS (1mg/L)
Bacillus thuringiensisisraelensis
(bio-chemical)

73. BIOLOGICALCONTROL
LarvivorousFish
Advantages
Environmental friendly
Easy to introduce
Self propagating & self sustainable
User friendly
Helps build community participation &
intersectoralcollaboration
Cost-Effective -no recurrent costs
Gambusiaaffinis
Lebisterreticularis

74. BIOLOGICALCONTROL
LarvivorousFish
Limitations
Extremes of temperatures and pollution
Suitable for some types of breeding sources only
Needs proper planning with mapping of
breeding sources & promotional efforts
Biolarvicide:
Bacillus thuringiensisiserailensis(Bti)-Endotoxin
: 2.5% suspension, 1 lit/50 m2, once every 2
weeks.
Aphaniusdispar

75. HEALTH EDUCATION
Impart knowledge to common people regarding the
disease and vector through various media sources like T.v.,
Radio,Cinema slides, PAMPLETS etc.
VECTOR CONTROL
COMMUNITY
PARTICIPATION
Sensitizing and involving the community for
detection of Aedesbreeding places and their
elimination
4s
SEARCH AND DESTROY
SELF-PROTECTION
MEASURES
SEEK EARLY CONSULTATION
SAY NO TO INDISCRIMINATE
FOGGING

76. LEGISLATION
1.Model civic byelaws: fine/punishment is imparted, if
breeding is detected. In cities
Rohtak, Delhi, Mumbai, Chandigarh.
2.Building Construction Regulation Act: In
Mumbai, prior to any construction activity, the
owners/builders deposit a fee for controlling
mosquitogenicconditions at site by the Municipal
Corporation.
3.Environmental Health Act
4.Health Impact Assessments

77. OUTBREAKRESPONSE
Rapid response team:
Aim to undertake urgent epidemiological investigations
and provide on the spot technical guidance required and
logistic support.
Rapid response team: Rohtak
District malaria officer
D.F.W.O
SMO
Epidemiologist
MO CH (Med)
MO CH (Micro)

78. DENGUEEPIDEMIOLOGY
Introduction
Epidemiological determinants
Case definition
Diagnosis and treatment
Prevention and control
Recent update & myths

79. DENGUEVACCINE
Currently, there is no vaccine available in India
to protect against dengue.
In recent years the development of dengue
vaccines has accelerated dramatically.
Today, several vaccines are in various stages of
advanced development, with clinical trials
currently underway on five candidate vaccines.
http://www.denguevaccines.org/why-a-vaccine

80. http://www.denguevaccines.org/why-a-vaccine
Alive, attenuated, tetravalent dengue
vaccine (CYD-TDV) candidate, containing
four recombinant dengue viruses (CYD1-4)

81. The fifth variant DENV-5 has been isolated in October
2013.
The likely cause of emergence of the new serotype could
be genetic recombination, natural selection.
GM (Genetically modified Mosquito) –Male sterile
mosquitoes are released in environment so as to mate
with wild females and produce sterile eggs. It is still in
experimental stage.
http://nvbdcp.gov.in/Doc/Dengue-FAQ-2015.pdf

82. Spread the dengue prevention
message to others…
Let your
family, friendsand
neighboursknow
about the dangersof
breeding Mozzies!!
THANK YOU …