Malaria Atlas Project Flashcards
Malaria
» Mosquito-borne disease, endemic in only some parts
of the world
» Symptoms can be mild or life-threatening
- Mild symptoms include fever, chills, and headache
- Severe symptoms include fatigue, confusion, seizures,
and difculty breathing
» Some people are at higher risk of severe infection:
children under 5 years, pregnant women, travelers,
and people living with HIV
- Children under 5 are at greatest risk of dying from
malaria, representing around 60-80% of all deaths
Malaria transmission
» Spread through bites of infected
Anopheles mosquitoes - Not directly person to person
» Micro-organism = Plasmodium - P. falciparum - P. vivax » Life-cycle: after infection the
parasite spreads to a person’s
liver, then to their blood, then to
another mosquito
Burden of disease due to malaria
Globally, 1.1% of all deaths due to malaria In Nigeria, 12.5% of all deaths due to malaria
Key points
» Malaria is a mosquito-borne disease that is endemic in only some parts of the world.
» The two most common types of malaria are Plasmodium falciparum and Plasmodium vivax.
» In some countries, malaria is one of the biggest causes of death (e.g. 12% of all deaths in
Nigeria), and one of the top three causes of death in children under fve.
» Multiple methods of prevention (insecticide treated bed nets, indoor residual spraying,
seasonal malaria chemoprevention, vaccine) and treatment (artemisinin-based
combination therapy).
» Global programs have been efective in controlling malaria, though progress has stalled over
the past ten years.
Artemisinin-based combination therapy (ACT)
» Relatively quick and efective treatment for mild
cases of malaria
- Three-day course of tablets
» In some countries, community case management
of malaria through volunteer/paid community
health workers
- Children with fever given ACTs and referred to the
nearest health centre
» For severe malaria, patients need intravenous or
intramuscular treatment
Malaria prevention and treatment
» Malaria can be prevented by avoiding mosquito
bites and with medicines.
- Vector control
* Indoor residual spraying (IRS)
* Insecticide treated bed nets (ITNs, LLINs)
- Pharmaceuticals
* Seasonal malaria chemoprevention (SMC)
* Malaria vaccine
» Treatments can stop mild cases from getting worse.
- Artemisinin-based combination therapy (ACT)
Insecticide treated bed nets (ITNs)
» Highly efective and responsible for a
large part of the global reduction in
malaria cases since 2000
» Requires people to have a net (access)
and to sleep under it (use)
» Net quality and insecticide
efectiveness can deteriorate over time
- Regular ITN distribution campaigns
are needed
Malaria
- Malaria is a major global disease
- Caused by the Plasmodium parasite (Plasmodium falciparum, plasmodium vivax, etc.)
- Spread by the Anopheles mosquito
- Accounts for approximately 600 thousand deaths a year (>1 per minute)
The global fight against malaria
Malaria funding saw a major increase from 2000 to 2010 (MDGs)
* Substantial reductions were achieved but we remain far from global eradication, and the
funds are still not enough (it is estimated around $7.8 bn USD was required in 2022).
The global fight against malaria
How can we make progress?
* Needs more resources
* Resources need to be used more effectively
How do we achieve this?
Improved situational awareness:
* Malaria risk is very variable across space & time
* So where do we target resources?
The Malaria Atlas Project (MAP) was founded in 2005 with the aim to develop
a quantitative evidence base on the global distribution of malaria risk
Geospatial Statistics
Decision making under uncertainty
we can’t know exactly the nature of malaria risk throughout a country but we can be rigorous in describing our
uncertainties: this allows assumptions and sensitivities to be tested
Statistical Models
Malaria-metric data is ‘noisy’ and incomplete (only a small fraction of children in a small
fraction of villages are surveyed at any given time): we need statistical models to make
useable maps
MAP: History
2005 – 2019: Oxford
* Three pillars of activity:
* Data - ongoing assembly and curation of all available (georeferenced) malaria data + climatic & environmental
information
* Analysis - development of wide range of statistical models to
use these data to address policy relevant questions
* Engagement and dissemination – Passive (MAP
website); Active via policy engagement, collaboration
* Progressive growth in funding, team, scope, impact over the years
But why do we need a model?
Data is sparse
In space… And in time….
Geospatial Statistics
Concerned with statistical inference using geographical data
* Emerged from the field of mining: ‘kriging’ method to estimate
ore body volumes (esp. Georges Matheron: 1930-2000)
* A new era thanks in part to increasing computational power (esp.
Peter Diggle: ‘model based geostatistics’; Sylvia Richardson &
Nicky Best)
MAP: History
Since Sept 2019: Curtin and The Kids Research Institute Australia
* (Gradual) relocation of entire program: Team of 30 in Perth
* Primarily BMGF funding - portfolio approx $15M
Challenges facing MAP
- Inaccurate/incomplete data
- Lack of adequate information on contextual factors
Routine surveillance data offers the possibility of continuous risk monitoring, but there remain issues with accuracy of
data capture and missingness from non-attendance
Tobler’s first law of geography:
“everything is related to everything
else, but near things are more
related than distant things”
A model allows us to
- Fill in the gaps
- Standardise observations between locations, timepoints, and methodologies
- Inform policy-making, funding decision, and to track our progress against malaria
Challenges facing MAP
Human geography:
* people’s movements through the risk and
treatment landscape complicate data
interpretation and modelling
e.g. place of residence not necessarily place of infection
* data on behavioural factors such as time spent
outside during peak mosquito feeding hours is
scarce
- point data: observations from a single location (has GPS coordinates, village/school name):
e.g. survey of patent parasitaemia amongst children from a given village
Challenges facing MAP
Updating and innovating our methods whilst maintaining a consistent historical view to
track progress in malaria fight
MAP provides estimates for the World Malaria Report and Global Burden of Diseases
studies: consistency of method is very important for continuity
Challenges facing MAP
Decolonising global health: how to be an effective ally for emerging scientists from LMICs
* opening of new MAP office in Tanzania (Susan Rumisha; Punam Amratia)
* taking training and workshops to endemic countries; focus on NMCPs and stakeholders
* collaborations and sub-awards/consulting to local researchers (e.g. Ezra Gayawan; FUTA)
Geographical data for the geography of malaria
geographical (γῆ-γραφω) data: data on people, environment, climate etc. tied to location
(and time)
- geographical image data: a pixel-grid of observations (has a coordinate system):
e.g. satellite-based radar elevation measurements
- areal data: observations covering an extended region (has a described boundary):
e.g. counts of reported malaria cases in a local government area
MAP: Data
- Environmental/climatic covariates
(geographical image data) coordinate system, time, measurement
there is a lot of work to process the original satellite-based products into useable covariates (gap-filling for cloud cover,
bad pixels, etc)
MAP: Data
- Infection surveys (roughly 50,000 datapoints)
(point data): location, time, number positive, number tested
MAP: Data
- Case reporting (~90,000 admin units)
(areal data) area, time, number of cases
primarily passive surveillance: relies on cases reaching a health clinic and being captured in reporting systems
Malaria
- Clinical malaria (uncomplicated):
fever, chills, headache, sweating, nausea
(249 million clinical cases globally in 2022)
Malaria
- Severe malaria: loss of consciousness,
seizure, severe anemia, difficulty breathing
(608k deaths globally; mostly children)
Malaria
- Economic costs: loss of productive work
days / school days; cost of medicine and
care seeking
Malaria treatment and prevention
- Chemoprevention treatments: mass coordinated distribution
to vulnerable populations including children and pregnant women to
clear infections and interrupt transmission. This includes
o Seasonal malaria chemoprevention (SMC) - for children 6mnth – 5yrs
o Intermittent preventive treatment for pregnant women (IPTp)
o Perennial malaria chemoprevention (PMC) - for children below 2 yrs
o Mass drug administration (MDA) - for populations in low malaria settings
Malaria treatment and prevention
- Artemisinin-based combination therapy (ACT): quick reduction in
parasite load from artemisinin then longer acting partner drug takes
care of remainder - Insecticide-treated bed nets (ITN): prevent infection (kill mosquitos +
physical barrier) - Indoor residual spraying (IRS): insecticide coating on walls kills resting mosquitoes
Three main streams of work
Skills, Backgrounds and Experiences
Our goals
- We assemble global databases on malaria risk and
intervention coverage, and develop innovative analysis
methods that use those data to address critical questions.
Our goals
- These include better understanding the global landscape of
malaria risk, how this is changing, and the impact of malaria
interventions.
Our goals
- By modelling burden, trends, and impact at a fine
geographical scale we support informed decision making for
malaria control at international, regional and national scales.
Why do some countries have more cases of malaria
than other countries?
● Different country population size – more people in a country means more possible cases of malaria (or of
any disease)
● Different mosquito populations (specifically, Anopheles mosquitoes)
● Different capacities to prevent and treat malaria (i.e. stronger/weaker health systems)
● Different baseline prevalance of the disease - more humans with malaria makes it more likely that mosquitoes will pick it up and transmit it
Describe three different malaria prevention strategies
● Malaria can be prevented by avoiding mosquito bites and with medicines.
○ Vector control
○ Insecticide treated bed nets (ITNs, LLINs)
○ Indoor residual spraying (IRS)
○ Reducing/treating stagnant water
Pharmaceuticals
○ Seasonal malaria chemoprevention (SMC)
○ Malaria vaccine
Insecticide Treated Bed Nets (ITNs) are an effective way to prevent malaria.
If you were going to run an ITN distribution campaign, how would you design it?
● Needs to include components for BOTH “access” and “use”
● ACCESS - making sure every household has an ITN - ideally, at least 1 ITN for every 2 people
○ Can distribute via health facilities, schools, central pick-up points
○ Priortise families with children, pregnant women
● USE - making sure people are actually sleeping under the nets (through awareness-raising, education, behaviour change programs)
● Frequency = campaigns every 2 to 3 years, because ITNs degrade in quality and effectiveness over time
● Why do we need data on malaria?
● What is the difference between
“empirical data” and “modelled data”?
● Why, specifically, do we need
“modelled data” on malaria?
Should a country prioritise prevention, treatment, or both if they experience:
- A high number of cases, but few deaths
- A low number of cases, where most result in death
- A high number of cases, where most result in death
● Need to determine whether to focus on prevention or treatment
○ If high number of cases, but few deaths, priority would be prevention (i.e., to reduce malaria cases and therefore malaria MORBIDITY)
○ Can do this through ITN campaigns, indoor residual spraying, seasonal chemoprevention, malaria vaccine
○ If low number of cases AND same number of deaths, you should likely focus on treatment (i.e., to reduce those few cases from progressing to severe/life-threatening malaria)
○ Can do this through increasing access to artemisinin-based combination therapy (ACTs); for example, through
community health workers
○ If high number of cases AND high number of deaths, you could arguably focus on both prevention and treatment -whichever is likely to be most effective
● Key point - it can depend, but in all scenarios, if there are any cases and any deaths, both prevention and
treatment are likely to have some effect
