By comparing water quality of the upper Ganges, the team showed that levels of 'blaNDM-1' were 20 times higher per capita during the pilgrimage season than at other times.
Monitoring levels of other contaminants in the water, the team showed that overloading of waste treatment facilities was likely to blame and that in many cases, untreated sewage was going straight into the river where the pilgrims bathe.
"The bugs and their genes are carried in people's guts. If untreated wastes get into the water supply, resistance potential in the wastes can pass to the next person and spiralling increases in resistance can occur," the researchers warned.
"If we can stem the spread of such antibiotic resistant genes locally - possibly through improved sanitation and waste treatment - we have a better chance of limiting their spread on larger scales," contended Grahem who has spent over 10 years studying the environmental transmission of antibiotic resistance around the world.
The concern is growing worldwide over the threat from bacteria that are resistant to the so-called 'last resort' class of antibiotics known as Carbapenems - especially if resistance is acquired by aggressive pathogens.