Monday, April 06, 2009

Mapping Sexually Transmitted Diseases

Toronto Start STD Map

I thought that it would be a while before the Toronto Star managed to beat the popularity of their Toronto Neighbourhood map.That map proved hugely popular in Toronto and the paper was inundated with comments, e-mails and letters in the form of "congratulations, suggestions, and pleas from overlooked communities for a spot on the map". However the Toronto Star's latest Map of the Week may generate just as much publicity, being a map of sexually transmitted diseases in the city.

The paper has produced five different Google Maps showing the rates of Chlamydia, Gonorrhoea, HIV, Infectious Syphilis and Other Syphilis in different neighbourhoods in the city. The data for the maps comes from the Ministry of Health in response to a freedom of information request.

A good analysis of the maps is available on the Toronto Star's website here. It would be interesting, however, to see these maps in conjunction with other data, such as average income, levels of health insurance etc.

Mapping of diseases has a very long history. Perhaps the most famous disease map is the spot map created by John Snow in 1854. Snow created his map to show the cases of cholera in Soho, London. The map helped to prove that the Soho outbreak of the disease was caused by water that came from one pump in Broad Street. The dominant theory at the time was that cholera was caused by "bad air", so John Snow's map helped to prove the true cause of the disease.

This video gives a good account of what John Snow's map making achieved,

The Ghost Map by Steven Johnson from Book Videos on Vimeo.

Google themselves make good use of maps on their own Google Flu Trends website. have produced a global disease alert map with data from ProMED-Mail, the World Health Organization, EuroSurveillance and Google News



Anonymous said...

As an epidemiologist, I love maps and especially maps of diseases, since it's fun to gaze at them and speculate. I have helped out county STD workers with data interpretation, including maps, and in the US a big problem has to do with what gets reported. STDs are required to be reported, but it's usually the lab that reports, not the doc. And in more affluent neighborhoods, the doc will look over the symptoms, decide what the STD is, and treat it without sending it to the lab (who would report it to the county health dept). That way his/her patient doesn't get "VD" on his/her chart nor have that embarassing phone call from the county health dept. As a result, there's a strong bias for more STDs getting reported from poorer areas, and less from richer areas. The actual rates may differ some, but against the reporting bias it can be real tough to ferret out. And the docs are legally required to report those STDs, so, yes, they are breaking the law.

Karen Sinclair said...

I like the idea of being able to track diseases like the flu via Google maps. Also being able to track the STDs in my area is very cool idea as well and I hope all the dating and singles websites add it to there websites!