26 October 2011
WALIS: Google Earth Typhoid Maps Reveal Secrets of Disease Outbreaks
In the mid-nineteenth century, John Snow mapped cases of cholera in Soho, London, and traced the source of the outbreak to a contaminated water pump. Now, in a twenty-first century equivalent, scientists funded by the Wellcome Trust working in Kathmandu, Nepal, have combined the latest in gene sequencing technology and global positioning system (GPS) case localisation to map the spread of typhoid and trace its source.
Recent advances in DNA sequencing have allowed scientists to accurately track the spread of some diseases by measuring mutations in the pathogen's DNA when the DNA replicates.
However, tracing the spread of typhoid has proved challenging as these mutations are small in number and not detectable by most techniques in use.
Tracing outbreaks of typhoid in Kathmandu also carries its own problem: street names are not used in Nepal, so capturing the addresses of typhoid cases -- and hence accurately mapping the outbreaks -- has proved challenging to health workers.
Web link to full article. Source: Science Daily