The house flies is the aircraft carrier that stores millions of fleets of disease-causing microorganisms on their feet. Yes, of course this is possible because they often land in dirty places including feces, then colonize your food or drink.
That is their powerful way of paralyzing humans, thereby developing typhoid, dysentery, cholera, and even trachoma-causes of blindness due to the wounding of the cornea or the clear lining of the eye that lies in front of the iris and afflicting 500,000,000 worldwide.
There are also other types of flies that also spread the disease, for example: Tsetse flies that became a means of transmission of protozoa causes sleep disorders. Blackflies are the cause of river blindness in 400,000 Africans. Sand flies that cause leismaniasis-a set of diseases that cause paralysis, are destructive, and fatal.
All image im capture by macro lens