Outbreak

Surveillance and Response
to Prevent Malaria
Re-emergence
Alexandre Macedo de Oliveira, MD, MSc, PhD
Division of Parasitic Diseases and Malaria
Centers for Disease Control and Prevention
• Discuss thoughts about malaria reemergence
(thoughts, due to limited information on the
topic)
• Discuss interventions to prevent and/or
respond to such events
• Keep recommendations focused on what
feasible, or advisable, in the context of the
Americas
Terms of Interest
• Malaria importation
– A person acquires malaria in an endemic area
and goes to a non-endemic area
• Malaria introduction
– First-generation transmission of malaria
originating from an imported case in a
malaria-free area
• Indigenous malaria
– Local malaria transmission without any direct
link to an imported case
Terms of Interest
• Malaria outbreak
– Increase in number of expected cases in a
given area during a period of time
– Either increase from baseline transmission or
reintroduction
• Malaria reemergence vs. reestablishment vs.
reintroduction
– In most cases, referring to the same thing
(though not always)
Malaria Reemergence
• Receptivity
– Presence of vectors, and ecological/climatic
conditions favorable to malaria transmission
– How capable area is to allow for transmission
• Vulnerability
– Proximity to malarious areas or possibility of
influx of malaria patients or vectors
– Possibility of malaria parasite introduction
Preparedness
• Risk assessment and monitoring
• Programmatic and systemic readiness
for response
• Malaria surveillance
– Detection of initial cases
• Ability to respond
Risk Assessment and Monitoring
• Malariogenic potential
• Factors influencing vulnerability and
receptivity
– Migration patterns, climate, rainfall
• Malaria early warning systems
– Different ways to set up such a system
Systemic Readiness
• Maintenance of malaria expertise for malaria
control and prevention
• Difficult in countries that reached malaria
elimination
– Tendency to lose expertise once malaria no
longer a concern
• Expertise and commodities ready to
deployment
Systemic Readiness
• Malaria preparedness plan
– Information on roles and responsibilities
during an outbreak or reemergence episode
– Guidance on leadership, involvement of other
public health programs, communication
chain, resources mobilization
– Description of relationships and reliance
on external partners
– Operating procedures for intervention
implementation of control interventions
Systemic Readiness
• Response team
– At minimum: an epidemiologist, a
laboratorian and an entomologist
– Desirable: logistician, communication
specialist, etc
• Supply chain
– Availability of drugs and diagnostic
supplies
Malaria Surveillance
• Detection and reporting of cases
(during outbreak and not!!)
• Basis for appropriate treatment
• Reliance on laboratory proficiency
– Need to be maintained
Entomological Monitoring
• Ground work done as part of preparedness
• Areas with malaria receptivity and/or
vulnerability
– Yearly monitoring of vector composition
and insecticide resistance even if no
transmission
– Support decisions on control measures
Outbreak Definition
• Increase in number of expected cases in
a region during a period of time
• In malaria-free areas
– One, just one!!, introduced or
indigenous malaria case is an outbreak
Response Mode
• Dynamic, activities and their intensity
changing over the course of a response
• Beginning
– Case detection
• Timely laboratory confirmation by expert
microscopy or molecular methods of all
cases
• In-depth interviews to asses place of
infection and collect demographic info
(imported vs. introduction and indigenous)
First Steps in Response
• Inventory of local, regional and national
capacity to respond
• Mobilization of proficient staff for laboratory
diagnosis and case management
• Availability of supplies
• Definition on communication channels and
leadership roles
Laboratory Methods
• Microscopy
– Gold standard method
– Dependence on microscopists
expertise
• Rapid diagnostic tests (RDTs)
– Less sensitive
– No quantification
• Molecular-based tests
– Little role in outbreak detection
– Complementary (later) important role
Laboratory Preparedness
• Maintenance of microscopy expertise at
either local or regional/central level
– Continuous training needed
• Availability of reagents and equipment
– Appropriate supply chain (Edgar’s
expertise!!)
• Plans for scaling up microscopy capacity
if needed
• Timely result reporting systems
Laboratory Preparedness
• RDTs as alternative for timely case management
(treatment decisions)
• Quality assurance and control systems in place
and running
• Mandatory collection of smear for confirmation
(all positive cases, all or a sample of negative
cases)
• Consider collection of samples in filter paper for
future molecular testing
Treatment Preparedness
• Availability of good quality drugs (Edgar’s
expertise again)
• Appropriate regimens for implicated
species and strain
– Issue of chloroquine-sensitive
parasites
– If in doubt, cover chloroquine-resistant
parasites
• Training of healthcare workers in
identifying, testing and treating cases
Initial Cases Follow-up
• Close clinical and parasitological monitoring
to ensure treatment compliance and parasite
clearance
– Difficult as transmission progresses
• Adopt broader case definition (less specific)
of suspected malaria case, eg fever
• Reinforce passive case detection and
reporting in neighboring areas
Case Finding
• Active case detection
– Public health officials identifying
and reporting cases
– Time consuming on response team
• Passive case detection
– Healthcare workers or laboratorians
identifying and reporting cases
– Risk of missing cases
• Generally a combination of the above
Contact Investigation
• Evaluation of home and work contacts of
confirmed cases
– Determination of radius for contact
investigation (most cases, household
contacts and immediate neighbors)
– Testing of all contacts or only symptomatic
contacts
• Epidemiological decision
• Most infected people symptomatic in non-
endemic areas
Contact Investigation
• Evolving contact investigation strategy
during re-emergence episodes
1. Only symptomatic contacts
2. All contacts irrespective to symptoms
3. Population-based surveys
• Epidemiological decisions
– More is not always better
Surveillance
• Plot cases in time and space
• Geographic mapping by place of residence
or probable place of infection
• Periodical analysis of data and decisions
on what follow up/control measures
• Decisions based on data, not assumptions
if possible
Control Measures
• Proper case management
– Identification of cases
– Accurate diagnosis
– Proper treatment
• Vector control
– Indoor residual spraying
– Insecticide-treated nets (ITNs)
– Larviciding in special cases
• Limited and localized breeding
Questionable Interventions
• Fogging
– Limited value, temporary effect
• Mass drug administration
– Risk of drug overuse and side effects
– Cost effective when malaria prevalence
>55–70%
Follow-up Studies
• Case-control studies
– Determine causes and mechanisms of
transmission
– Often later in an outbreak response
– Not a reason to delay implementation of
control interventions
• Molecular analysis
– Genotyping
– Later in outbreak for evaluation of
dissemination patterns
Acknowledgements
– Melissa Briggs
– Jaime Chang
– Kathrine Tan
– Kumar
– John Barnwell
– Audrey Lenhart
– Bill Brogdon
– Many others
Gracias!
– Melissa Briggs
– Jaime Chang
– Kathrine Tan
– Kumar
– John Barnwell
– Audrey Lenhart
– Bill Brogdon
– Many others
Gracias!
– Kumar
– Jaime Chang
– John Barnwell
– Audrey Lenhart
– Melissa Briggs
– Kathrine Tan
– Bill Brogdon
– Many others
Laboratory Network
• Availability of quality microscopy, if
possible
• RDTs as ‘first-line’ diagnostic tool but
smears taken for confirmatory
• Samples in filter paper for subsequent
– Confirmatory assays
– Genotyping and resistance testing

Source: http://proyectomalariacolombia.co/files/amiravreda/Martes%209/Alexandre%20Macedo.pdf