Most of them were fungi, but there were also bacteria that can cause dysentery, tuberculosis and ulcers. (Illustration: C R Sasikumar) Most of them were fungi, but there were also bacteria that can cause dysentery, tuberculosis and ulcers. (Illustration: C R Sasikumar)

There are dozens of disease-causing micro-organisms travelling inside your wallet. A study by a group of scientists reached the conclusion after studying currency notes in denominations of Rs 10, Rs 20 and Rs 100, procured from markets in south Delhi.

Scientists at the Institute of Genomics and Integrative Biology (IGIB) — one of the top-ranking institutes under the Council of Scientific and Industrial Research (CSIR) — found traces of DNA footprints of at least 78 disease-causing micro-organisms on these notes, though not all of them on a single one.

Most of them were fungi, but there were also bacteria that can cause dysentery, tuberculosis and ulcers.

What the study implies is that currency notes often act as carriers of these micro-organisms and can spread microbial diseases.

“To be sure, the study only looked at finding traces of DNA. So we know what kind of organisms could have been on these notes. We do not know whether these organisms have the ability to infect people with the disease because we did not study that aspect. But what we can certainly say is that there is a possibility of diseases spreading through this manner because the microbes do actually travel through currency notes,” S Ramachandran, who led a group of five students for the project, told The Indian Express.

This is not the first time such a study has been conducted. A technology called Ribosomal RNA typing has been used to identify the taxonomy of organisms on objects like clothes, furniture, soaps, even computers.

“We have used a different technology — high-throughput DNA sequencing — for our study. This is a relatively new technology and much more powerful. Using this technology, we can extract lots of information even from a very small amount of DNA material. The other benefit of this method is that even those microbes which cannot be cultured can be detected,” Ramachandran said.

The notes were collected from street vendors, grocery shops, snack bars and local market places in south Delhi. The samples were put through the DNA sequencing technology and a bioinformatics algorithm was run on the results.

“We were actually surprised to find traces of so many organisms. It was only a student project. We found some antibiotic resistant genes as well. An infection by these can lead to the person developing resistance to certain antibiotics,” Ramachandran said.

He said a larger investigation was needed to assess the possibilities of diseases getting spread by currency notes.

“Our study is an eye-opener. But it was a small project. We should look at a larger area, use a greater sample and do a more comprehensive study on this,” he said.

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