How do flies spread disease?

After a nasty experience overseas with flies crawling all over food, I ask myself, how do flies actually spread disease? We all kind of know this and spend our time shooing flies off food and drinks.

This is what I love about writing a blog, it gives me the opportunity to research a wide range of topics. I am researching this after another nasty bout of gastroenteritis; had attended a Balinese wedding where the flies had to been seen to be believed. It was like we were in a tent designed to keep the flies in with the flies contacting everything.

So my research tells me flies collect pathogens on both their legs and mouths carrying the diseases on the small hairs or bristles on their legs and bodies. So the next question is, what is a pathogen? A pathogen is an infectious agent that may also be described as a biological agent causing disease and illness.

We have all seen flies land on objects and rub their rear legs together so this makes sense. By rubbing its legs together, the fly is able to scrape of some of the material that has gathered on its bristles contaminating the area it has just landed on.

The diseases they carry include typhoid, cholera and dysentery - all diseases that will mess you up big time. More diseases, such as salmonella, anthrax and tuberculosis are carried by flies - but I'm guessing these diseases are less likely. Flies feed on feces and as were on a Balinese farm, they had a rich food source as the farm was unclean, you could smell it.

The farm really reeked of the foul stench of animal faces so I'm guessing they were not big on cleaning the animal stalls. The local population seemed none too bothered by all this and with all the rubbish including plastic around the area were not big on hygiene at all. I don't want to be a rich westerner looking down at poor people in developing nations; you can be poor and work hard to clean up where you live.

Due to their sponge type mouths, flies feed on liquids requiring them to liquefy their food through regurgitation. Flies eat by throwing up their stomach contents on their food source with the digestive juices breaking the solid matter into smaller chunks. Flies then use their proboscis to recover the stomach contents by drinking the digestive juices and dissolved food source.

Fortunately, despite the feeling of wanting to continually vomit and crap your pants with explosive diarrhea, the effects seem to wear off after a couple of days although diarrhea and dysentary is a leading cause of deaths in developing countries. In my case it wrecked Christmas day and a three-day trip to Rottnest Island on my return home.