Hi, Thanks for writing in HCM. Viruses and bacteria are very small organisms that cannot be seen by naked eyes. You need not get scared by the fact that your friend has told about it. But, any dirt ingestion can cause bacterial or viral infection of GI tract, which manifests in the form of fever, nausea, vomiting or diarrhoea. But these things can be prevented by taking antibiotics and other medications. Hence don t be worried as of now. If you get any or few of the above symptoms, seek medical help immediately. Hope the information provided would be useful.