Scientists are combining gene sequencing technology with Google Earth to help map the spread of typhoid and trace the source of the illness in Nepal.

Typhoid fever is caused by bacteria and usually spread through food or water contaminated with fecal matter. Outbreaks of the illness have been difficult to track because the pathogen mutates, and also because health workers have had a tough time determining the exact locations of cases. Many homes in Nepal do not have street addresses.

In research published Monday in the journal Open Biology, health workers in Nepal's capital, Kathmandu, used global positioning system or GPS to capture the exact location of a typhoid case and then post the information on Google Earth.

Based on that information, researchers found that people living near communal water spouts and living at a lower elevation had the greatest risk of contracting the disease.

Stephen Baker, a scientist with Oxford University's Vietnam unit, said until now, it has been extremely difficult to study how organisms such as the typhoid-causing bacteria evolve and spread at a local level.

He says new advances in technology have allowed researchers for the first time to create accurate geographical and genetic maps of the spread of typhoid.