Mapping the epidemiology of malaria to guide control and elimination
For over 20 years, the KEMRI-Wellcome Trust programme has been interested in how malaria parasite exposure affects disease outcomes in African children [Snow et al., 1997]. A natural extension of this work began in 1996 with the formation of a collaboration between the Kenya programme and the South African Medical Research council in Durban to develop a cartography of malaria parasite exposure across Africa – The Mapping Malaria Risk in Africa (MARA) project [Snow et al., 1996; MARA/ARMA, 1998]. This collaboration, one of the earliest Pan-African research networks, sourced empirical data on parasite prevalence from across the continent and developed climate based maps of transmission suitability for every endemic African country. These maps can still be found today in many ministry of health offices.
Developing a cartography of malaria risk, while resurrected in in the 1990s by MARA, was a routine exercise during the Global Malaria Eradication era from the 1950s to late 1960s for many African countries. Early national malaria control and eradication programmes saw maps as a necessary tool to decide where to target resources and how to approach control based upon a mapped epidemiology of risk. Importantly, malariologists surveyed entire countries for malaria infection prevalence, layered information on climate, ecology and mosquito vector distributions, providing malaria programmes with a detailed understanding of all the spatial dimensions of malaria to design control. This level of enquiry, skills in cartography and the need for epidemiological intelligence waned across Africa when the continent focused less on malaria elimination and more on providing less specialised services to presumptively treat fevers though primary health care.
The Roll Back Malaria initiative was launched at the end of the 1990s, at a time when Africa was gripped by an escalating epidemic, widely used drugs were failing and vector control was almost non-existent. The international response, through the Roll Back Malaria initiative, was to presume one-size-fits all for the delivery of proven vector control measures and treatment strategies. A legitimate response to galvanize donor support at a time of an epidemic, without the need for any detailed mapping below national levels, but an approach that inevitably led to wastage and inappropriate use of resources in many settings.
In response, in 2005, the Kenya programme, under the leadership of Professor Bob Snow established the Malaria Atlas Project (MAP), to continue the work established by MARA in Africa and beyond to provide a global risk analysis of malaria infection [Hay & Snow, 2006; Guerra et al., 2007]. This project led to several important publications on the global distributions and intensity of P. falciparum transmission [Hay et al. 2007] that fed into international priority setting agendas for unmet needs for vector control [Noor et al., 2009; Noor et al., 2010] and global malaria funding allocation [Snow et al., 2010].
MAP, now managed from Oxford UK, continues to serve as a vehicle for international partners to monitor progress in global malaria investment, but does not support the specific needs of malaria risk mapping at country-levels.
In 2013, the programme developed the Information for Malaria (INFORM) project with Department for International Development (DFID) and Wellcome Trust UK funding. The ambition of this programme is to resurrect the level of interest shown during the 1960s through the use of mapped epidemiological features of malaria to design cost-effective control at sub-national levels. Three important aspects govern this work a) all in not equal and one-size does not fit all regarding what and when to deliver to control malaria in any country; b) health resources, including malaria commodities, are distributed and managed below federal levels – at district, county or state levels – consequently increasingly higher spatial resolution epidemiological, climate and population data are required to guide targeted sub-national priority setting and resource allocation; and c) developing this body of knowledge can only be done effectively though collaborations with departments responsible for malaria control within ministries of health at country levels, where ownership of all data and products is firmly with country partners and not research institutions in the north.
Between 2013 and 2014, epidemiological profiles were developed in partnership with ministries of health in eight, high burden African, countries: Tanzania, Uganda, Nigeria, Malawi, Mali, Ghana, Ethiopia and the Democratic Republic of Congo. Smaller projects were also undertaken by the INFORM team in Sudan, Madagascar, Rwanda, Eritrea and Cote D’Ivoire. This was a difficult task in such a short space of time, but coincided with a changing international response to malaria funding that demanded more intelligent use of available data to rationalize control ambitions below national levels. The eight profiles were instrumental in providing the context necessary for countries to secure over 1.5 billion USD in funding from the Global Fund in 2014-2015.
In 2015, DFID-UK decided to extend the work started by INFORM to integrate this work with UK Government support to the WHO African Regional Office (AFRO) to improve the use of data to inform malaria decision making. The INFORM team in Nairobi partnered with the London School of Hygiene & Tropical Medicine (LSHTM), UK – to form the LSHTM-INFORM-NMCP-Knowledge (LINK) project (url) – to work more directly with countries under the leadership of WHO-AFRO in evolving the data assembly, capacity building and use of malaria epidemiological profiles and risk mapping to support malaria strategic planning and financing across 20 countries.
The renewed appetite for the assembly, analysis and use of epidemiological data to define malaria control and elimination ambitions is one of the legacies of the programme’s work across the Africa region since the mid-1990s. The future of malaria in Africa will depend on the granularity of understanding of its ever changing epidemiology. As Professor Snow is quick to point out “this cannot be done simply through research publications, it will only have meaning and impact when there is a true sense of data ownership at country-levels, building the capacity to analyse complex data through partnerships between ministries of health and national academia”.
Beyond the AFRO region countries face different challenges in malaria risk mapping. Since 2016, Professor Snow and his team have been working with the WHO Eastern Mediterranean Regional Office (EMRO) malaria department providing technical support on the history of elimination, P. falciparum and P. vivax risks using community survey and routine health system data and the mapped threats to future elimination posed by conflict, human population movement and marginalized groups. This work is focussed on Sudan, Somalia, Djibouti, Yemen, Saudi Arabia, Pakistan, Afghanistan and Iran.
Snow concludes that “After 20 years of traditional science funding and publication to the Kenyan Major Overseas programme, the exciting product of this is its application to real world problems, working with national governments and regional agencies – this is a new way of doing business, likely to have a much greater and more sustainable long-term impact on malaria in the WHO EMRO and AFRO regions”
Snow RW, Marsh K, le Sueur D (1996). The need for maps of transmission intensity to guide malaria control in Africa. Parasitology Today, 12: 455–457
Snow RW, Omumbo JA, Lowe B, Molyneux SM, Obiero JO, Palmer A, Weber MW, Pinder M, Nahlen B, Obonyo C, Newbold C, Gupta S, Marsh K (1997). Relation between severe malaria morbidity in children and level of Plasmodium falciparum transmission in Africa. Lancet, 349: 1650-1654
MARA/ARMA (1998). Towards an atlas of malaria risk in Africa. First technical report of the MARA/ARMA collaboration. Durban, South Africa; https://idl-bnc.idrc.ca/dspace/bitstream/10625/31644/1/114833.pdf
Snow RW, Okiro EA, Gething PW, Atun R, Hay SI (2010). Equity and adequacy of international donor assistance for global malaria control: an analysis of populations at risk and external funding commitments. Lancet, 376: 1409-1416
Noor AM, Alegana VA, Patil AP, Snow RW (2010). Predicting the unmet need for biologically targeted coverage of insecticide treated nets in Kenya. American Journal of Tropical Medicine & Hygiene, 83: 854-860
Noor AM, Mutheu JJ, Tatem AJ, Hay SI, Snow RW (2009). Insecticide treated net coverage in Africa: mapping progress in 2000-2007. Lancet, 373: 58–67
Hay SI & Snow RW (2006). The Malaria Atlas Project (MAP): developing global maps of malaria risk. PLoS Medicine, 3: e473
Guerra CA, Hay SI, Luciopariedes LS, Gikandi P, Tatem AJ, Noor AM, Snow RW (2007). Assembling a global database of malaria parasite prevalence for the Malaria Atlas Project. Malaria Journal, 6: 17