dengue seminar september 2011
DESCRIPTION
The slides used in the presentation by the Sri-lankan team, at the Seminar at SIMS, Lahore.TRANSCRIPT
Epidemiology of Dengue in Sri Lanka: past, present and future
Hasitha Tissera MBBS, MSc, MDConsultant Epidemiologist
Ministry of Health Epidemiology Unit
Ministry of Health Sri Lanka
Dengue SeminarSeptember, 2011
Outline
• Background
• Pre-endemic period
• Endemic period
• How we could change the epidemiology
Dengue
• Most important mosquito borne viral infection in the world
• Very common infection in tropics • Large epidemics occur • Nearly 90% of infections in children• Wide spectrum of infection outcomes Asymptomatic infection → Death • High morbidity, relatively low mortality disease
Transmission Modulating FactorsTransmission Modulating Factors
Vector Host (human) Virus
Dispersion
Density
Deposited eggs
Vector’s competency
Individual immnunity
Herd immnunity
Sequential Infections
Individual factors
Magnitude of the Epidemics (DF/DHF)
Serotypes
(Previous Circulation)
Genetic differences
Virulence
Probability of Transmission
Source: Prof. Maria Gloria Teixeira, London May 2008
Dengue: Global burden Dengue ploriferates from 20th to 21st century with increasing burden, despite a lot of hard work on control and prevention
1960 2004
Why Epidemiology ?
• To aid in setting health priorities
• To aid in setting research priorities
• To identify prospective health interventions
• To provide a comparable measure of output for interventions
Pre-endemic History• Clinical dengue-like illness from beginning of 20th century
• Serologically confirmed in 1962
• First outbreak in 1965
• D1-D4 circulating since at least 1966
• 1965-68 had 51 cases and 15 deaths
• 1969 – 88’ multiple outbreaks of DF with occasional DHF
• Mostly from Western Province• School cohort study 1980-85’ (pre DHF): Dengue sero- prevalence 50% (7000, 5-7 year olds in Colombo MC)
Endemic Period – 1989 onwards
• DHF became endemic in 1989*• 1989 – 203 hospitalized with 20 deaths (CFR 9.8%)• 1990 – sharp increase to 1300 cases and 54 deaths
(CFR 4%)• 1991- 95’ – multiple outbreaks • 1996 – became nationally notifable disease
*Source: Vitarana T, Jayakuru WS and Withane N, Ministry of Science Technology and Human Resources, 1993
Temporal and Spatial Spread, 1996 - 2009
1996 2004 2005 2006 2009
N=1294 N=15463 N=5994 N=11980 N=35007
Reported Cases to National Epidemiological UnitReported Cases to National Epidemiological Unit
Dengue Trends in Sri Lanka
2009 CFR – 0.99%2010 CFR – 0.71%2011 CFR - 0.71%
2004 : 7 districts >100 2009 : 13 districts >100
Geographic Expansion 2004 - 2010
Incidence 80/100,000 Incidence 170/100,000
2010 : 21 districts >100
Incidence 170/100,000
2004 2009 2010
6
197
318
181
73104 92
36 38 28 15 6 526
< 1 year 1-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 >60
Age group
0
100
200
300
400
Nu
mb
er
Dengue cases by age groups Sri Lanka - 1996 and 2006
38
209
352
261
339
513
366
257
189141
10958 38
64
< 1 year 1-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 >60
Age group
0
100
200
300
400
500
600
Num
ber
No. of cases analysed N= 2934
38
327
493
395
532
904
808
510425
318260
198127
218
< 1 year 1-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 >60
Age group
0
200
400
600
800
1000
Num
ber
No. of cases analysed N= 5553
Data as 22/01/2008
1996
No. of cases analysed N= 1125
Source: Epidemiology Unit Sri Lanka
Overall Sero-prevalence among children < 12 – 52% study supported by PDVI
Seasonality
• South-western monsoon peak: May – July • North-eastern monsoon peak: Oct - Jan
South-west monsoon North-east monsoon
What we did to control & prevent
• Vector control through awareness – until 2004 • With epidemic shift in 2004:
- Active social mobilization- Aggressive vector control- Attempt improvement in clinical management
Where are we today
• In general to date , the targeted health interventions largely not sustainable, less effective than expected. Why?
• A few model countries on effective surveillance (Brazil), Vector control (Singapore, Cuba) and effective clinical management (Thailand, Vietnam) exist, but are exceptions.
WHY IS DENGUE SUCH A BIG PROBLEM TODAY?
• Global population growth
• Rural to urban migration
• Growth of cities• Deterioration of
cities
• Jet travel• Health services
poorly organized/ underfunded
• Lack of vector control professionals
Slide courtesy of Dr. Scott Halstead
Which Perspective Do We Take?
SOCIETY
PATIENT
FAMILY
GOVERNMENT
ALL OTHER STAKE HOLDERS
SCIENCE
Slide courtesy of Dr. Ananda Amarasinghe
National Plan: Outputs
1. Improved Case Management2. Strengthened Surveillance – disease,
laboratory, entomological3. Capacity building – at all levels infrastructure,
staff, equipment, 4. Strengthened control activities at National,
Provincial, District, & Divisional levels5. Enhanced intersectoral & community
participation for sustainable programme
Dengue Epidemiology
• Primary Prevention:(A)Reduce disease transmission (interruption) –
solidifying evidence based vector control approach;
- improved entomological assistance - adult vector control
(B) Vaccine – preparation for vaccine introduction when become available (earliest 2015) – need to plan now
Dengue Epidemiology…
• Secondary Prevention: (A)Early case detection – Iry care & pvt. sector
through improved diagnostics:- Full Blood Count - NS1 (cost implications)
(B) Improving Clinical Management - reducing disease severity- reducing case fatality
National Guidelines 2010
1%
49%
37%
13%DF
DHF I & II
DHF III
DHF IV
Statistics LRH Ward 04 - 2009Statistics LRH Ward 04 - 2009
Source: Infection Control Unit LRH + Ward 04 records Slide courtesy of Dr. Padmakanthi Wijesuriya, Consultant Paediatrician LRH
DF
DHF I & II
DHF III
DHFIV
Total Dengue Patients : 333(Jan-Aug 2009)
5,565
12,422
Source: Epidemiology Unit Data
Dengue Situation by Month201120102009
To bring down mortality…
Scott B. Halstead, M.D.
Providing Micro-haematocrit Machines to Hospitals
Setting up of National ‘Hotline’
Standardized teaching and training curricula at all levels
Advocacy - Highest Level
• Health
•Local Govt.
• Environment
• Defense
• Education
• Media
High - risk areas June - July 2011
Major Breeding Habitats Urban Breeding Sites Rural Breeding Sites
Discarded containers – plastic cups, tins, cans, bottles.…
Discarded containers – coconut shells, clay pots, bottles ….
Water Storage –tanks, barrels, buckets Water storage – tanks, barrels, buckets
Used Tyres - domestic, workshops, depots
Used Tyres – domestic, workshops, depots
Roof Gutters - domestic, offices, high-rising building tops Roof Gutters – domestic, sun shades
Other – ornamental items, blocked drains, construction sites, natural breeding -ornamental plants, underprivileged communities, bare lands
Other – spare part yards, natural breeding sites -bamboo shoots, tree axills/holes, fallen tree leaves, plantations
www.epid.gov.lk
Regular update on dengue situation
Thank You!