New research indicates that those of us who are acutely sensitive to houseflies may have a point after all. A study published in Scientific Reports found that two of the most common or garden insects – houseflies and blowflies – are both capable of carrying hundreds of different bacteria. And the bad news is that a significant portion of this is ultimately harmful to humans.
Houseflies have always been seen as pestilent creatures, but this latest evidence is something of a revelation. It is known that flies are born from faecal matter and rot, so in the sense they hardly sound like the cleanest of creatures. But this study has been the first to analyze the gut content of these insects, and assess the potential of houseflies to carry and deliver dangerous germs.
Considering the prominence and propensity of houseflies, this obviously poses serious health implications. Donald Bryant, co-author of the new study and a professor at Penn State, suggested that the authorities must move now to acknowledge the risks entailed.
“We believe that this may show a mechanism for pathogen transmission that has been overlooked by public health officials, and flies may contribute to the rapid transmission of pathogens in outbreak situations,” Bryant commented.
Researchers analyzed the microbiome of 116 houseflies and blowflies spread across three different continents in the study, along with the microbial content of individual body parts. They discovered that the likes of houseflies are particularly responsible for transmitting germs and disease, and that this should be taken seriously by households across the world.
Study co-author Stephan Schuster explained the dangers involved. “The legs and wings show the highest microbial diversity in the fly body, suggesting that bacteria use the flies as airborne shuttles. It may be that bacteria survive their journey, growing and spreading on a new surface. In fact, the study shows that each step of hundreds that a fly has taken leaves behind a microbial colony track, if the new surface supports bacterial growth,” Schuster commented.
Traces of the human pathogen Helicobacter pylori where found in a 15 cases in Brazil, which should be considered fairly worrying considering that this blight can also cause ulcers in the human digestive system. Houseflies have never previously been considered as a possible carrier of this disease, and thus at least the new study has been significantly informative for health campaigners.
Rural / urban divides
Researchers also discovered that both houseflies and blowflies are rather similar in terms of stomach contents, sharing approximately half of their microbiome. Another interesting morsel of information which cropped up in the study is that houseflies residing in urban environments picked up more germs than those living in rural areas.
“It will really make you think twice about eating that potato salad that’s been sitting out at your next picnic. It might be better to have that picnic in the woods, far away from urban environments, not a central park,” Bryant suggested.