Thursday, 1 March 2012

MALARIA: Developing the ‘Atlas of Human Infectious Diseases’

1 Mar, 2012 Heiman Wertheim, Wellcome Trust

A map showing human cases of monkeypox in Africa
Map showing human cases of monkeypox (red dots) in Africa

Released last week, the Atlas of Human Infectious Diseases is a collection of up-to-date maps presenting the status of major human infections around the world. Dr Heiman Wertheim, one of its editors, reflects on the reasons for compiling the atlas and on the necessity of good data for a better understanding of infectious diseases.
My career as a clinical microbiologist has been based on understanding the special preferences of infectious agents for specific niches and hosts. During my training, I encountered Mary Wilson’s book A World Guide to Infections and realised that, in order to render infectious diseases easily understandable, one has to display the overwhelming amount of available data using concise presentations like maps. A World Guide to Infections was an eye-opener, as it comprehensively displayed the distribution of infectious diseases using tables, texts and several maps.
Since then, whenever I see a world map of the distribution of an infectious disease, I wonder who made it, what data was used to make it and, most importantly, why the disease is confined to specific regions. Digging deeper, I often find that it is difficult to find the sources for the maps and inaccuracies are not uncommon. (Please let me know if you find any in our atlas.) There is a pressing need for good maps with verifiable sources. And collecting all of these infectious disease maps together in one book would allow the reader to leaf through and discover similarities between diseases and ecological niches, which helps in understanding their distribution.

Map showing cases of human African trypanosomiasis (sleeping sickness), species of parasite and distribution of tsetse flies

Map showing cases of human African trypanosomiasis (sleeping sickness), species of parasite and distribution of tsetse flies

That was our aim, then, although it took many years to go from from idea to proposal, to secure funding and find a publisher, and, of course, to do the actual work. The map-making began in 2007; several maps made at that time needed an update by the end of 2010. As the distribution of infectious diseases adjusts to a shifting environment (war, deforestation, flooding and other changes), maps need periodic updates. Therefore, this atlas should be seen as a starting point and a living document. Besides showing the status of infectious diseases through to 2011, the atlas also helps explain why diseases occur where they do, by showing the driving forces behind them.
I hope that this atlas will inspire health professionals to submit their own epidemiological data when they see it has not been included. In particular, data from Africa is often absent due to lack of good diagnostics or of any incentive to publish findings. It is worrying that most countries on this vast continent are regularly depicted in the grayscale of ‘No data’, except when it concerns HIV, malaria, poverty or lack of sanitation. We hope this will change in the near future with the help of this atlas. Too often the aetiology of disease syndromes is based on data from the ‘developed world’. This is often misleading: for instance, Streptococcus suis is a common cause of adult bacterial meningitis in several South-east Asian countries, where it is more frequent than the Streptococcus pneumoniae or Neisseria meningitidis that typically cause the disease in Western countries. This kind of information has important consequences for treatment.
It has been a wonderful experience to assemble this atlas with Jack Woodall and Peter Horby. I am honoured that Mary Wilson has written the foreword for this atlas, as it was her book that set this all in motion

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