Traditionally, tracking diseases such as typhoid, and in particular working out where outbreaks begin, has been a little difficult to accomplish. In the case of fighting the disease in a country like Nepal, the problem is two-fold - not only is the rate of spread difficult to track, but because of the lack of a street address system, plotting cases visually has been almost impossible. Fortunately, this is about where Google Earth steps in.
A team of scientists from the Wellcome Trust Major Overseas Programme based in Vietnam, with a Clinical Research Unit from Oxford University, have managed to create a map of the disease distribution using GPS data and Google Earth, using the service API to accurately model the spread of the disease.
The particular advantages of visualising the data is that the typhoid bacteria - Salmonella typhi and Salmonella paratyhpi - tend to mutate the further and longer they are allowed spread.
This new research, a report on which has been published in the most recent edition of Open Biology, has also refined the technique DNA sequencing techniques in order to more easily detect these changes, and map the level of mutation to individual cases on a local scale.
"Until now, it has been extremely difficult to study how organisms such as the typhoid-causing bacteria evolve and spread at a local level," said Dr Stephen Baker.
"Without this information, our ability to understand the transmission of these diseases has been significantly hampered. Now, advances in technology have allowed us for the first time to create accurate geographical and genetic maps of the spread of typhoid and trace it back to its sources."
The scientists doing the legwork would take blood samples and a GPS reading at homes of patients, using the blood to sequence the bacterial genotype, and the GPS data to locate the case on Google Maps.
They also mapped the locations of water sources used by the local community, which often are the sources of typhoid outbreak.
Typhoid is considered endemic in many parts of South East Asia, due to lack of access to sanitised drinking water. According to major study by the World Health Organisation, the disease was responsible for over 200,000 deaths in 2000.
