How Google Earth is being used to track Typhoid in Nepal

For most of us, going a day without using a Google product is unimaginable. The internet giant serves up our news, email and maps. It gives us the internet on a platter, all from a single domain. Occasionally you’ll use it to do something you’d never thought of before and you’ll think you’re pretty damn clever. Chances are, though, you never thought of using a Google tool to track a deadly disease in a remote mountain kingdom.

That’s precisely what a team of scientists working in Kathmandu have done. Using Google Earth and gene sequencing technology, the researchers have been able to accurately map the spread of typhoid in the Nepalese capital for the first time.

In a 2008 study, Kathmandu was described as “a typhoid fever capital of the world”, with thousands of cases reported every year. Outbreaks, however, have been difficult to chart in a city where the streets frequently have no names.

The researchers claim they used GPS signalling and the latest DNA sequencing techniques to plot the course of the disease. Among the most significant of their discoveries is that the source of outbreaks is usually a communal water spout.

The research, recently published in the journal Open Biology, was carried out by scientists at the Vietnam-based Wellcome Trust Major Overseas Programme and the Oxford University Clinical Research units in Kathmandu and Ho Chi Minh City.

“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 Stephen Baker, a scientist with Oxford University’s Vietnam unit.

“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.”

Health workers visited the homes of individual patients, using GPS technology to capture their exact location. This data was then plotted onto Google Earth.

They also took blood samples from hospitalised patients to isolate the organism –which mutates as it spreads – and allow analysis of its genetic makeup to identify the disease’s point of origin.

The researchers found that those most at risk were people living near communal water spouts and at low elevation.

“Improvements in infrastructure are fundamental to the control and elimination of typhoid”, said Baker.

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