who perspective and guidance on burden of dengue, -...
TRANSCRIPT
ALERT AND RESPONSE OPERATIONS
WHO perspective and guidance
on burden of dengue,
prevention and control and
integrated management
Dr Raman Velayudhan
Coordinator, WHO Geneva
Global Dengue Risk 2012.
Simmons CP et al. N Engl J Med 2012;366:1423-1432
Commitment Chronological list of World Health Assembly resolution and Regional Committee resolutions adopted since 2000:-
World Health Assembly
2002 - WHA 55:- Dengue fever and dengue haemorrhagic fever prevention and
Control. WHA 55.17
2014 – World Health Day April 7th – Vector borne diseases
2015 – EB and WHA 68 Dengue prevention and control
Regional Committee Resolutions (RCM):-
2001 – PAHO: Dengue and Dengue Haemorrhagic fever. CD43.R4
2008 – SEAR: Dengue prevention and control. SEA/RC61/R5
2008 – WPR: Dengue fever and dengue haemorrhagic fever prevention and
Control. WPR/RC59.R6
2011 – EMR: Dengue: call for urgent interventions for a rapidly expanding emerging
Diseases. EM/RC/58.R4
2013 – EURO Framework on Invasive species surveillance and control
Goal: To reduce the burden of dengue
Objectives:
• To reduce dengue mortality by at least 50% by 2020*
• To reduce dengue morbidity by at least 25% by 2020*
• To estimate the true burden of the disease by 2015
Technical element
1: Diagnosis and
case management
Technical element
2:
Integrated
surveillance and
outbreak
preparedness
Technical
element 3:
Sustainable
vector control
Technical
element 4:
Future
vaccine implementation
Technical
element 5:
Basic
operational and
implementation
research
Enabling factors for effective implementation of the global strategy:
Advocacy and resource mobilization;
Partnership, coordination and collaboration;
Communication to achieve behavioral outcomes;
Capacity building; and
Monitoring and evaluation
The global strategy for dengue prevention and control (2012- 2020)
Burden Project objectives
1. To carry out needs assessment in select priority countries and develop and integrate all heath care providers dengue data in the national health information system;
2. Develop and field test a guidance document on estimation of true burden of dengue at national level including real time tracking of cases.
3. To estimate the economic burden of dengue during outbreaks /epidemics on health systems in selected countries
Selection and obtaining approval of participating countries in the project
Brazil
Mexico
Sri Lanka
Maldives
Singapore (tbc)
New Caledonia (tbc)
Cambodia
Tanzania (tbc)
Fiji (tbc)
Ecuador
• Criteria for the selection of countries:-
• endemicity of dengue;
• existence of a national programme;
• existence of health information system;
• availability of designated staff as dengue focal point;
• potential for introduction and evaluation of new tools
Deconstructing burden
• Different levels of severity
• Impact & cost are age-dependent
• Probability of lab-confirmed diagnosis low, especially for milder disease
Severe
Fever
Infection
{ Medically attended
(hopefully)
• Major Conclusions
• WHO endorses and uses the burden estimates derived from the Oxford group studies.
• The estimates and risk map will be updated in 2015 using new data
• 91 cohorts available, 47 are using D/SD
• Regular surveillance data continue to be collected and used
• WHO is piloting burden estimation in 5 countries
• Challenges
• The gold standard for measuring dengue incidence is active detection through serology, but case detection from hospitalization is more commonly used
• Need to refine burden estimates for a better prediction framework using force of infection
Burden estimation
• Major Conclusions
• Availability of RDT/NS1
• Progress has been made on evaluating the performance and
utility of different kinds of diagnostic tests (IGM-based, NS1-
based, Combination IgM/NS1, molecular diagnostics)
• Laboratory networks have been established in some regions
• Challenges
• Performance of kits varies across populations and countries
and manufacturers – needs an evaluation process
• Resources for the use of diagnostics
• Strengthening global dengue laboratory networks globally
requires enrolment and supporting development of national
laboratories
Case management: diagnostics
Major Conclusions
Case classification (D/SD) and treatment algorithms have been developed aiming to reduce case mortality and help clinicians for triage.
Implementation/acceptance varies across regions and countries
Ongoing studies will provide more information on the predictive value of warning signs and case definitions
Challenges
Opinion varies about the redefining case classifications for dengue
Harmonizing classifications is necessary based on solid evidence
Case management: clinical management and classification
l Major Conclusions
– Integrated surveillance is important for risk assessment and situation awareness
– Integrated surveillance can support outbreak preparedness and development of appropriate public messaging.
l Challenges
– Prioritizing combinations of components that are applicable to resource-limited settings
– Surveillance must be followed with a locally appropriate response, however evidence supporting what works is severely limited
Integrated surveillance
• Major Conclusions
• Primary purpose of outbreak response is to meet peak demand during
epidemics.
• Theoretically early outbreak detection and prediction provides an
opportunity for interventions to moderate the size of the outbreak,
especially if the response is early and robust.
• Ongoing studies are attempting to establish systems for outbreak
detection and prediction using hospitalized cases as a parameter
• There are instances where outbreak control has been successful in
curtailing dengue (eg Iquitos and Cairns)
• Challenges
• Identification of key parameters for each epidemiological setting for
prediction of outbreaks
• Improving quality of data
• Effectiveness of any outbreak response has not been validated and
depends on timing of initiation.
Outbreak Response
l Major Conclusions
– Multiple tools are available
– Promising tools are in the pipeline (eg. Wolbachia, GM mosquitoes, vector traps, environmental management)
– Current and new tools and strategies have not been systematically evaluated for dengue prevention/ control against epidemiological outcomes and cost effectiveness
l Challenges
– Scalability, coverage, sustainability, acceptability and quality of delivery remain an issue.
– Implementation of best practices in vector control studies in relation to dengue.
Sustainable vector management
A Critical Assessment of Vector Control
for Dengue Prevention
NL Achee, F Gould, TA Perkins, RC Reiner, Jr., AC
Morrison, S Richie, DJ Gubler, and TW Scott
• Major Conclusions
• Recent results on the first successful Phase III trials were published
• A number of candidates in clinical and preclinical pipeline
• Dengue is challenging to model, but several approaches are
underway to model the impact of vector control and vaccine
interventions
• Countries that wish to introduce the vaccine will need to embark on
preparatory measures
• Challenges
• Potential public health impact and cost effectiveness of the first
commercially available vaccine remains to be determined
• Challenges remain in the implementation (eg. target populations,
vaccine schedules, acceptability, affordability, long term
effectiveness)
• Application of modelling framework to combine vaccines and vector
control
Introduction of vaccines and combined interventions
l Major Conclusions
– Partnership for Dengue Control (PDC)
• Integrated approach in dengue control as a concept
• Three major objectives: 1) developing the research agenda, 2)
develop advocacy and communication and 3) ensuring
sustainability through fundraising.
– Intersectoral partnerships
• Health sector, environment sector and community partnerships
for dengue control are essential (eg. Singapore)
– Regional partnerships
• Several regional partnerships exist, for example- UNITEDengue
l Challenges
– Need for synergistic effort
– Evidence for effectiveness of partnerships
Partnerships
STRATEGY IMPLEMENTATION NEEDS
Capacity building
Communication for
Behavioral outcomes
Advocacy and
Resource
mobilization
Partnership,
Coordination and
collaboration
Monitoring and
Evaluation
Technical
elements
Amarasinghe et alia, Emerging Infectious Diseases (2011) 17:1349-1354
Known or Suspected Dengue Endemic Countries: Africa
Known endemic
Suspected endemic
Urban, semi-urban and rural movement
Human movement –critical and understudied component in transmission
Facilitate identification of hot spots, prompt response and suppress outbreaks
Surveillance, intervention and prevention
Points of entry needs to be monitored for vectors under IHR (2005)
Climate change favours the vectors
Erratic access to piped water may aggravate dengue incidence if it leads to increased domestic water storage.
Increase in temperature favours the multiplication of the vector and the virus
Rainfall, relative humidity, El nino all plays a role in transmission and more studies are needed
First CRCT of success of vector control.
Each site implementing the intervention in its own way has the advantage of local customization and strong community engagement.
Community mobilisation
Malaria 1 Dengue OLD NEW
Population at risk 3.2 billion 2.5 billion 3.9
billion
Endemic countries 96 >100 128
Infections /year 214 million 50 million 70- 500
million
Severe Cases 3 million 2.1 million
?
Deaths/ year 438,000 20,000 10,000*
1) Global Malaria Report 2015 2) http://www.pdvi.org/about_dengue/GBD.asp and Brady et.al. PLoS Negl Trop Dis 2012; 6: e1760
• Uncertain distribution and burden
• As malaria declines, dengue rises
• Impact of Environmental changes
• Silent expansion of the vector
• Urban health services and systems
needs to be addressed
A disease for the future ?