According to this study, researchers proposed that swarms of flies can be used to help monitor disease outbreaks. This follows their research that shows how whole communities of bacteria known as a microbiome. This bacterium can "hitch a ride" on common carrion flies and can be transferred to any surface where the flies land. The study is published in Scientific Reports.

By sequencing the genetic material of 116 houseflies and blowflies along with all the microorganisms that they are carrying, the team found that each of these flies carried up to several hundred-different species of bacteria, some of which may be harmful to humans.

One of these, Helicobacter pylori, is a pathogen that can cause stomach ulcers in humans and is the strongest known risk factor for gastric cancer. Although known to be spread via body fluid and smear infections, this is the first time that H. pylori has been shown to be spread via flies in the environment.

"To date, diseases transmitted by a mechanical vector like flies have been a major overlooked pathway by both the medical and academic community. This is a great example of how observations from basic research on how diseases spread might be translated into viable and useful applications, opening new avenues for future technology."

New way of sequencing flies

The research findings were made possible thanks to a new way to collect flies without contaminating them with additional microorganisms, and then sequencing every single part of a fly's body from its head and thorax to its legs and wings. First, the flies are baited by a piece of rotting fish, followed by the researchers holding a container with dry ice close to the flies.

The cold vapour from the dry ice sedates the fly and it falls into the cold container untouched and uncontaminated. After the fly is defrosted in a sterile environment, the various parts are separated, crushed and then put into a gene sequencing machine. The resulting data is then sorted out by a supercomputer.

After filtering the genetic data from the fly's own chromosomes, mitochondria and symbiotic bacteria, what is left is the microbiome that can be matched to a database of all known bacteria DNA and RNA. Flies in the study were collected from four different continents around the world: Australia, Brazil, the United States and Singapore.

"There were quite a lot of flies landing on our sweaters at Prof Marshall's farm and it was really easy just putting small containers with dry ice to capture them. They were literally dropping like flies," said Prof Schuster.