How To Solve a Problem Like Malaria

Developing Effective Health Interventions

According to the World Health Organisation, there were an estimated 219 million cases of malaria worldwide in 2017 and 435,000 deaths from the disease. Nine out of ten (93%) malaria deaths occurred in Africa and more than half of all deaths (61%) were children under five.

New vaccines offer hope for the future, but in the meantime antimalarial drugs remain the front-line medical intervention. However, prevention of infection by acting against the mosquitoes through bed-nets and insecticides is a major element in the fight against malaria.

Professor Chris Thomas, Global Chair in Water and Planetary Health at the University of Lincoln, specialises in modelling the transmission of vector-borne diseases like malaria by combining field ecology, remote sensing and geo-physical models with geographic information systems, spatial statistical and artificial intelligence computing.

A focus of his current work explores new methods for predicting the population dynamics of mosquitoes which transmit malaria in Africa, including how their spread is affected by climate change.

He is the Principal Investigator in the NERC-funded FLOODMAL project, an international collaboration deploying novel techniques to study malaria vector distribution on the Zambezi floodplain, a vast area with very high levels of malaria transmission in western Zambia. Professor Mark Macklin, Director of Lincoln’s Centre for Water and Planetary Health, is a co-researcher on the project.

“Since 2001 there have been huge reductions in malaria through the global malaria elimination programme,” explains Professor Thomas. “But in some areas such as western Zambia prevalence remains very high, whereas in other areas that have almost eliminated local transmission, such as Zanzibar - where we also have a new research programme - medical services are finding it difficult to shift in a last few entrenched areas. It's in these challenging situations where we think our approach could make a real difference.”

African malaria mosquitoes breed rapidly in open, shallow water left by rains, floods, and irrigated farmland. Malaria is often highly seasonal following the rains and water movement across the land, with mosquito population dynamics also affected by humidity and temperature. The impact of climate change on disease transmission is therefore a major concern for Professor Thomas and fellow scientists. Part of the puzzle is understanding how communities and services can best adapt to the public health consequences of these changes.

New methods of computer modelling using hydrological and hydraulic models of water distribution and flow combined with high resolution satellite imagery are being developed to predict and map, weeks in advance, the presence of water bodies where mosquitoes breed. The hope is that by understanding where water will be in relation to the distribution of human hosts, scientists can predict variation in the risk of malaria in fine detail across entire landscapes.

Professor Thomas added: “With the annual floods on the Zambezi becoming less predictable due to climate variability, a mobile human population, and several species of mosquito vectors implicated in transmission, it is becoming increasingly difficult to plan interventions needed to eliminate the disease. To tackle this we are working with the Zambian health service and a multi-disciplinary team of researchers from Zambia, Canada and the UK. We’re trying to predict transmission levels in this very dynamic landscape using our geographic-ecological techniques.”

The team is taking ‘big data’ approaches to studying disease transmission: new computing, biosciences and geographic technology allows them to do things that were practically impossible just a few years ago. Rapidly growing internet and mobile networks in Africa increasingly means information can now be disseminated quickly and easily. However, they still embark on many long 4x4 journeys as well, trapping mosquitos overnight in remote villages and wading in swamps to sample larvae!

Their interdisciplinary work is having a delivering valuable insights and having a major impact on the extremely complex issue of mapping and predicting the spread of malaria. 

Photo credit: James Gathany