rat flea

…distributed with some—such as the rat flea and the mouse flea—having been carried all over the world by humans. Native species of fleas are found in polar, temperate, and tropical regions.

…of infection—by bites of the rat flea. It is inappropriate to isolate human cases of a disease that is usually acquired by contact with infected farm animals or their products, as in the case of brucellosis. Even for diseases in which it may protect individuals, isolation will often have little…