Spatial epidemiology of NTDs


LASER compile and maintain the renowned Global Atlas of Helminth Infections (GAHI). A global open access resource of easy-to-use maps and tools which show the geographical distribution of neglected tropical diseases transmitted by worms: soil-transmitted helminthiasis, schistosomiasis, and lymphatic filariasis.

GAHI’s goal is to provide reliable and updated maps of helminth (worm) infection distribution that are essential to target treatment to populations in greatest need. Although many surveys of worms have been conducted, the data are rarely available in a form that is accessible to policy makers and the managers of public health programmes. This is especially true in Sub-Saharan Africa, where empirical data are seldom in the public domain.

Users are able to access maps by geographical location, by worm and by the type of map. To find out more visit

Spatial epidemiology of NTDs

Our early research in this area quantified the environmental conditions associated with the large-scale distribution of helminth infections at national and regional scales. This work has employed a variety of analytical approaches, including the use of Bayesian model-based geostatistics. Our work led to a number of insights into the ecology of infection at multiple spatial scales. This early work also led to the creation of the very first risk maps of the distribution of helminth infection in sub-Saharan Africa and demonstrated that GIS/remote sensing can provide an effective methodology for targeting NTD parasite control at realistic geographical scales.

As interventions are being implemented at scale, we are increasingly interested in the spatiotemporal distribution of NTDs. Understanding such distributions can assess the degree to which changes are related to the scaling up of interventions or other factors and can identify factors that contribute to the persistence or cessation of transmission. Better knowledge of the spatiotemporal distribution can also inform the design of optimal surveillance strategies.

Main areas of recent and current research include:

• Defining the global climatic limits of STH and LF
• Estimating the population at risk of infection and morbidity caused by STH
• Estimating the global distribution of trachoma
• Defining the pre-intervention distribution of NTDs, including STH, LF and trachoma
• Understanding the factors associated with changes in infection and with the persistence of transmission
• Modelling the contextual factors influencing the transmission of NTDs, including access to water and sanitation

We have also worked with the Task Force for Global Health to develop the NTD Mapping Tool, and the International Trachoma Initiative to develop the Global Atlas of Trachoma.

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