Flies are kind of disgusting, and definitely annoying. Since they’re so small and incredibly common, you might just swat them away when they land on your food and keep eating, but a study reveals that the little nuisances are even germier than previously thought. In fact, they can carry hundreds of different types of bacteria on their legs and wings. Cause for concern, or just disgustingly interesting? 
Researcher Donald Bryant of Penn State University said:
“People had some notion that there were pathogens that were carried by flies but had no idea of the extent to which this is true and the extent to which they are transferred.” 
“[The study] will really make you think twice about eating that potato salad that’s been sitting out at your next picnic. 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.”
For the study, researchers from Penn State, Singapore’s Nanyang Technological University, and the Federal University of Rio de Janeiro looked at data from 16 houseflies and blowflies collected from 3 different continents and sequenced the animals’ DNA to study their microbes.
The team found that houseflies carried about 351 different bacteria species, and the blowflies carried approximately 316. Both types of flies carried some of the same strains of bacteria.
The most common bacteria was determined to be Helicobacter pylori, or H. pylori, which can cause ulcers in the gut. Prior to the study, scientists hadn’t considered flies as a means of transmission for the bacteria.
Professor of genetics and genomics, Ana Carolina Junqueira said:
“This is the first study that depicts the entire microbial DNA content of insect vectors using unbiased methods.
Blowflies and houseflies are considered major mechanical vectors worldwide, but their full potential for microbial transmission was never analyzed comprehensively using modern molecular techniques and deep DNA sequencing.” 
Houseflies and blowflies pose the greatest risk to human health because they feed their young with feces and decaying organic matter, according to study co-author Stephan Schuster.
“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.”
So the next time you see a fly wobbling back and forth on Grandma’s jello mold, it may be time to reach for the trash can.
 Pulse Headlines
 New York Post