Research
An updated atlas of human helminth infections: the example of East Africa
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* Corresponding author: Simon Brooker simon.brooker@lshtm.ac.uk
1 Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK
2 Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
3 Vector Control Division, Uganda Ministry of Health, Kampala, Uganda
4 Neglected Tropical Disease Control Programme, Access Project, Kigali, Rwanda
5 Division of Vector Borne Diseases, Kenya Ministry of Health, Nairobi, Kenya
6 Projet Maladies Tropicales Négligées, Bujumbura, Burundi
7 National Institute for Medical Research, Mwanza, United Republic of Tanzania
8 Eastern and Southern Africa Centre of International Parasite Control, KEMRI, Nairobi, Kenya
9 School of Population Health, University of Queensland, Australia
10 Human Development Network, The World Bank, Washington DC, USA
11 Centre for Tropical Medicine, University of Oxford, UK
International Journal of Health Geographics 2009, 8:42 doi:10.1186/1476-072X-8-42
Published: 9 July 2009Abstract
Background
Reliable and updated maps of helminth (worm) infection distributions are essential to target control strategies to those populations in greatest need. Although many surveys have been conducted in endemic countries, 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. In an attempt to address the paucity of geographical information on helminth risk, this article describes the development of an updated global atlas of human helminth infection, showing the example of East Africa.
Methods
Empirical, cross-sectional estimates of infection prevalence conducted since 1980 were identified using electronic and manual search strategies of published and unpublished sources. A number of inclusion criteria were imposed for identified information, which was extracted into a standardized database. Details of survey population, diagnostic methods, sample size and numbers infected with schistosomes and soil-transmitted helminths were recorded. A unique identifier linked each record to an electronic copy of the source document, in portable document format. An attempt was made to identify the geographical location of each record using standardized geolocation procedures and the assembled data were incorporated into a geographical information system.
Results
At the time of writing, over 2,748 prevalence surveys were identified through multiple search strategies. Of these, 2,612 were able to be geolocated and mapped. More than half (58%) of included surveys were from grey literature or unpublished sources, underlining the importance of reviewing in-country sources. 66% of all surveys were conducted since 2000. Comprehensive, countrywide data are available for Burundi, Rwanda and Uganda. In contrast, information for Kenya and Tanzania is typically clustered in specific regions of the country, with few records from areas with very low population density and/or environmental conditions which are unfavourable for helminth transmission. Information is presented on the prevalence and geographical distribution for the major helminth species.
Conclusion
For all five countries, the information assembled in the current atlas provides the most reliable, up-to-date and comprehensive source of data on the distribution of common helminth infections to guide the rational implementation of control efforts.