A science study conducted on 3 continents

Researchers from the NTU Singapore realised a science study with 62 species of blowflies and 53 species of houseflies on 3 continents (Brazil, the United States and Singapore).

• Urban sites included a food market, the emergency entrance of a public hospital, a public park in a metropolitan setting, a sanitary landfill for household waste and a hawker centre/food court.
• Natural environment included a protection area at the Instituto Nacional de Pesquisas Amazônicas in the Amazon rainforest.
• Rural sites included a poultry farm and a mixed farm with animal stables for pigs, horses, chickens and cattle.

The blowfly (species Chrysomya megacephala)
Picture by Muhammad Mahdi Karim

The housefly (species Musca domestica)
Picture by Muhammad Mahdi Karim

In total, 431 bacteria were found on the flies, of which 316 have been identified on blowflies and 351 on houseflies. 7 types of bacteria have been found on 80% of all analysed flies, which include Escherichia coli and Enterobacter cloacae (causing food poisoning, pneumonia, breathing problems or urinary tract infections) and Enterobacter cloacae (causing lower respiratory tract and urinary tract infections). Also, the bacterium Helicobacter pylori has been found, which was unknown to be carried by flies (causing stomach cancer and stomach ulcers).
Looking uniquely at bacteria, blowflies carried 79 specific bateria and houseflies carried 114 specific bacteria. The majority of all bateria were found on their legs and wings.

Courtesy of Nature

It is known that flies carry bacteria, mainly from feeding and breeding in fecal and decaying organic matter, but until now it remained unknown about the actual potential. The reason for this is that it rarely lead to a medicial condition and therefore never was considered necessary.

The conclusion is that flies are incredibly dirty, so keep them out as much as you can. Have another snack ;-)

Source:
Nature