Scientists at the Wellcome Trust Major Overseas Programme in Vietnam and the Oxford University Clinical Research Units in Nepal and Vietnam have put Google Earth to good use once again. By using DNA sequencing technology and GPS, they have created a way to map typhoid outbreaks in Kathmandu, Nepal. They published their research in journal Open Biology.
It is extremely difficult to study how typhoid-causing bacteria, Salmonella typhi and Salmonella paratyphi, evolve and spread at local level. Using the new technologies mentioned above, the scientists have created accurate geographical and genetic maps of the spread of typhoid, enabling them to trace the bacteria sources. To make this possible, health workers visited patients’ homes and mapped the location with GPS. Using blood samples taken from the patients in the hospital, they determined the genotype of the typhoid strain.
After mapping and analysis, the researchers found clusters of typhoid infections in certain locations. People living near water spouts or residing at a lower elevation are at greater risk to get infected. Those two are likely to be interconnected, as the water spouts are more common in low lying areas. It also turned out that the disease predominantly spreads through the environment and less commonly through asymptomatic carriers.
The most important measures to combat typhoid are improvements of infrastructure, like water quality and sanitary conditions. Understanding the pattern of spread and the genotype, combined with treatment and vaccination, are not going to enable adequate control of typhoid without overhauling the water infrastructure that aids in breeding the disease.
Wellcome Trust press release: Google Earth typhoid maps reveal secrets of disease outbreaks …