Animated coloured scanning electron micrograph (SEM) of Cat flea (Ctenocephalides felis). It is the most common domestic flea and the adult cat flea, unlike many other fleas, remains on the host. Adults require a fresh blood meal in order to reproduce. Cat fleas are commonly found on both cats and dogs in North America, while dog fleas are found in Europe. The two species are distinguished by a slight morphological difference which is detectable only under high magnification. Cat fleas are capable of transmitting plague and murine typhus to humans, though such reports are rare. There are also varied allergic responses to their bites. Cat fleas serve as the intermediate host to an intestinal parasite, the dog tapeworm (Dipylidium caninum), which is transmitted to the pet when a flea carrying a tapeworm cyst is ingested.