There are doctors who rely on their sense of smell as a diagnostic tool, literally finding out what is wrong with a patient by using their noses. Certain diseases apparently have distinctive odors, caused by a change in metabolic processes associated with the patient's condition. A garlic odor is a sign of arsenic poisoning, and a fruity smell on the breath can mean either a diabetic or someone who is starving.
Here are some other illnesses and their distinct smells; German measles smells like plucked feathers; scrofula (a form of tuberculosis) smells like stale beer; typhoid like baking bread; yellow fever like a butcher's shop. Alert surgeons frequently check for bacterial infection by sniffing a patient's bandages. A musty cellar odor can mean an infected wound.