This is the most important reason why flies are more than just an annoyance. A common housefly (
Musca domestica) carries over
60 types of pathogens on its body and in its gut, including:
- Salmonella — one of the leading causes of food poisoning
- E. coli — causes severe diarrhoea, particularly dangerous for young children
- Staphylococcus aureus — resistant to antibiotics in MRSA form
- Cholera and typhoid fever — rare, but documented in areas with poor sanitation
- Intestinal parasites — eggs of certain parasites are carried directly onto food
The mechanism is simple and unpleasant: a fly lands on faeces or rotting organic matter, then lands on your food. While feeding, it regurgitates digestive enzymes onto the surface — effectively vomiting onto what you eat. In one minute spent on your plate, it deposits hundreds of bacteria.
With young children or people with weakened immune systems in the house, a fly infestation is not a comfort issue — it is a genuine health risk.