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Mapping Malaria

21 Nov, 2008

Abdisalan NoorIntegrated maps, combining data from satellites and other sources are providing new insights into malaria interventions. Mun-Keat Looi talks to Abdisalan Noor (pictured), a Wellcome Trust Research Training Fellow in Kenya, on his work in the field of geospatial modelling.

High-powered computers and earth-orbiting satellites may seem a world away from malaria, but these are the tools used by Wellcome Trust research training fellow Dr Abdisalan Noor to aid the fight against malaria.

Noor works on geospatial modelling at the Kenya Medical Research Institute-Wellcome Trust Research Programme (KEMRI), putting data from satellites and other sources into integrated maps that can offer fresh insights to a subject.

“Nearly all data are related to a specific location on earth,” explains Noor. “Geospatial modelling is the process of mathematically relating different spatial data to help us understand variables such as the prevalence of the malaria parasite, the distribution of a population, poverty or the coverage of insecticide-treated nets.”

Noor uses remotely-sensed data – such as that gathered from satellites, probes or other sensors – to define populations in terms of their socioeconomic status, risk of disease, access to healthcare, and how they respond to different health care interventions.

Maps for malaria

His first project updated a 40-year old record of Kenya’s healthcare services and he has also created poverty maps of Africa using satellite-derived data on night-time lights as a proxy for a region’s relative wealth.

But his primary focus is malaria. Noor is part of the Trust-funded Malaria Atlas Project, which aims to create a global map of where malaria parasites are found, and the degree of transmission within and between different areas. He helped construct Somalia’s first national map of malaria transmission using a combination of community-level data on malaria parasite prevalence and satellite-derived data on vegetation, temperature and rainfall.

His main interest is community-level interventions, specifically insecticide-treated nets (bed nets) that help protect people from the bites of malaria-spreading mosquitoes whilst they sleep at night. In particular, he has been looking at whether the distribution of the nets matches that of the disease, both geographically and over time.

“There are a lot of studies that have looked at how bed nets work in an experimental setting,” says Noor. “But few studies have examined how bed nets work when they are used in real life, where they are often provided in a random way – some people receive them, some don’t, two neighbouring villages may have completely different coverage, and people use them in different ways.”

Free bed nets

One of his studies, published in ‘PLoS Medicine’ in August 2007, compared the use of bed nets among Kenyan children with the way they were distributed by malaria programmes (see our news piece: Kenyan malaria success strengthens call for free insecticide-treated nets for all, 17 August 2007). Noor found that a two-week programme providing bed nets for free achieved a two-third rise in the number of children sleeping under a bed net, irrespective of whether the children came from rich or poor homes.

The findings helped persuade the WHO to change its policy – to recommending that bed nets should be distributed free instead of at a cost.

Noor’s most recent research – published in ‘the Lancet’ in November 2008 – has brought together information from malaria control programmes and national surveys from 40 different countries with data about populations, the distribution of bed nets, the prevalence of malaria, and measures of poverty based on night-lights. (See our press release: Bed net usage increases, but 90 million African children still exposed to malaria, 19 November 2008).

The study found that although the number of African children in malaria-endemic areas protected by bed nets has increased significantly – from 1.7 million in 2000 to 20.3 million by 2007 – there are still some 89.6 million children in Africa who remain unprotected. Over half of these children are in seven countries, with a quarter in Nigeria alone.

“The work shows people what is possible [with bed net intervention programmes] and where the gaps are. What is really needed is to gather more informative data to monitor how these interventions are scaled up and whether they are equitable or not,” says Noor. He adds that whilst many studies have looked at bed net coverage at a national level, this was the only one to look at the situation within countries over different time periods.

Feeding into policy

With the maps available free from the Malaria Atlas Project website, Noor hopes decision makers will use the data to design better programmes. However, he acknowledges that it can be difficult to get scientific data to feed into national policies.

“There seems to be a disconnect between policymakers and research scientists,” Noor says. “I think the problem lies on either side because sometimes it is difficult for scientists to package their findings for immediate policy use.”

KEMRI is tackling this by engaging policymakers at an early stage, working with government committees that are tasked with formulating policies and offering scientific evidence as a basis for their policy formulations.

Noor has links to the Kenyan government’s division malaria control programme and is a member of its monitoring and evaluation technical working group and insecticide-treated nets technical working group. He says KEMRI’s reputation for good science helps to persuade officials on the usefulness of their data.

“But it also helps that you are actually there when policymakers are thinking through the problems and trying to find solutions to those problems, instead of us coming in at the last minute and saying, ‘Hang on, you got it wrong. What you need to do is XYZ’. It’s always best to be there right from the beginning when they are formulating the policies and be part of it.”

References

Noor A et al. Increasing coverage and decreasing inequity in insecticide-treated bed net use among rural Kenyan children. PLoS Medicine, 2007.

Noor AM et al. Insecticide treated net coverage in Africa: mapping progress in 2000-2007. Lancet 2008, 372. doi:10.1016/S0140-6736(08)61345-8.

One Comment leave one →
  1. 2 Aug, 2013 4:27 pm

    Reblogged this on Science on the Land.

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