Ways by which house fly are harmful

Disease Transmission: House flies feed on and breed in filth, such as feces, garbage, and decaying organic matter. Their bodies and legs pick up pathogens (bacteria, viruses, protozoa, and parasitic worm eggs) from these sources. When they then land on food, surfaces, or directly on people, they can transfer these pathogens, causing various illnesses. Examples include typhoid fever, cholera, dysentery, food poisoning (like salmonellosis), and trachoma (an eye infection).

Contamination of Food: Even without direct disease transmission, their presence can contaminate food. They regurgitate digestive fluids onto solid food to liquefy it before consumption, which can introduce pathogens into the food. Their feces also contaminate food and surfaces.

Nuisance and Psychological Impact: The sheer presence of flies can be a significant nuisance, causing discomfort and distress. This can impact the enjoyment of living spaces and the perception of hygiene in homes, restaurants, and public areas.