Whenever flies fly around your premise, especially in high numbers, it becomes a nuisance. There are also some species of fly that pose a health risk to humans. In addition to transmitting diseases like salmonella, dysentery, tuberculosis, and cholera, house flies also carry parasites. 

Flies pose a high risk of disease transmission in India. Flies often cause cholera and dysentery epidemics during emergency situations, when hygiene conditions are less than ideal. Even under normal conditions, children and the elderly are at greater risk of more common diseases, such as salmonella food poisoning. 

The breeding habits and feeding habits of flies contribute to the spread of diseases. A fly feeds on bacteria that gets stuck in its mouth and on its footpads, which spreads all over them. Imagine if it was exposed food you were about to eat.