Typhus is a serious disease that people catch from the bite (or, more exactly, the droppings) of tiny insects that live on human and animal bodies — body lice, fleas, and mites. It gives you a very high fever, a bad headache, aching muscles, and usually a rash on the skin; before modern medicine it killed a lot of people. It is a formal, medical word. Where you meet it most is in history: it spread through armies, prisons, refugee camps, and ships — anywhere many people were crowded together, cold, and could not wash or change clothes. That is why it has old names like 'jail fever' and 'camp fever'. Today it is rare in places with clean water and washing machines, and antibiotics cure it, so most people know the word only from history books and films. Note that the insect does not really 'carry' the germ into you like a mosquito; you usually scratch the bite and rub the insect's dirt into the broken skin. Careful writers add a word in front — 'epidemic typhus', 'scrub typhus' — because these are somewhat different illnesses with the same family name.