Why House Fly Barf is an overlooked potential disease vector: ScienceAlert

The next time a fly lands on your food, you may want to consider getting rid of that sting. A new review suggests that slime that vomits from flies could be infected with pathogens.

When you think of an insect that carries a disease, you likely imagine a mosquito or tick that sucks blood. But recent results indicate the average non-biting housefly (house fly) may pose a greater threat to human health than is often perceived.

House flies have an organ at the beginning of their intestine known as the crop, which stores food before digestion. This organ also provides a great hiding place for microbes and parasites.

When you land a fly on your foodThere is a good chance that the insect will vomit some of the contents of its crop and some digestive enzymes. Without teeth, this is how a fly splits its meal so it can be sucked through its straw-like mouth.

In addition to spewing enzymes, the fly can also arch Viruses and bacteria from his crop, which was previously captured from other food sources, such as wounds, saliva, mucus or feces.

A recent review was made on the transmission path that was initially ignored due to the outbreak COVID-19 pandemicwhen the author, entomologist John Stovolano, read a book called Repercussions: Animal Infection and the Next Human Epidemic.

As Stovolano flipped between the pages, he realized that the houseflies he’d been working on for more than half a century had been largely overlooked as disease vectors.

“I was working on it [non-biting] Fly since I was a graduate student in the 60’s. And the [non-biting] The flies were largely ignored,” Says Stoffolano of the University of Massachusetts Amherst.

“Flies that feed on blood may shed light, but we must pay attention to the flies that live among us because they get their nutrients from humans and animals that secrete pathogens in their tears, feces, and wounds.”

Because flies are attracted to filth, such as dead animals and their faeces, non-biting insects are more likely to spread pathogens from animal to animal as they buzz.

According to one recent studymore than 200 different pathogens have been found in adult house flies, including some bacteria, viruses, worms, and fungi.

In 2020 researchers show up In laboratory experiments that can be carried by house flies SARS-CoV-2live transmission mechanically virus For new hosts on their legs, wings, or mouth parts.

But it’s not just a mechanical transmission that we need to worry about. In the nineties, a study I found it Escherichia coli Bacteria can multiply in the mouth parts of house flies.

In hindsight, Stoffolano now thinks this is happening because flies are constantly spewing out the contents of their crop during feeding and grooming (the insects smear their vomit on themselves).

In 2021, for example, a study I found that houseflies are infected Chlamydia tachomatis They can keep this pathogen alive in their crop for 24 hours – plenty of time to fly and vomit on a new host.

else study The pathogens present in the crop can remain for at least 4 days.

As scientists continue their work to understand these filthy creatures, keep in mind, however, that the risks are low if food is not left outside for too long.

“While there is little doubt that flies can carry bacteria, viruses and parasites from waste to our food, it is unlikely that a one-off landing would trigger a chain reaction that would lead to illness in the average healthy person,” entomologist Cameron Webb at the University of Sydney. Wrote in 2015.

However, many studies to date that have examined the insides of flies for pathogens have not identified which part of the flies they dissected. Stefano says researchers should examine the crop because it has more fluid for microbes and possibly parasites to bathe.

Researchers should also note that some species of flies have larger crops and, therefore, may be able to transmit more pathogens, posing a greater risk when those insects roam.

“It is the little things that cause problems,” Stovolano Says. “Our health depends on paying closer attention to these flies that live with us.”

The study was published in an insect.