Adult fleas are very small insects (up to 1/8 inch), so it is difficult
to see a number of the characteristics used to describe them. These
reddish brown to black, wingless insects are compressed from side to
side so that they look like they are walking "on edge." They have
piercing-sucking mouthparts through which they obtain blood meals from
their hosts.
The flea is suspected of transmitting murine typhus to humans, but its
primary importance is in its annoyance to people and pets. Cat fleas
readily try to feed on almost any warm-blooded animal. Some people are
bothered by the sensation of fleas walking on their skin, but bites are
the major nuisance. Bites tend to be concentrated on the lower legs but
can also occur on other parts of the body. The bite consists of a
small, central red spot surrounded by a red halo, usually without
excessive swelling. Flea bites usually cause minor itching but may
become increasingly irritating to people with sensitive or reactive
skin. Some people and pets suffer from flea bite allergic dermatitis,
characterized by intense itching, hair loss, reddening of the skin, and
secondary infection. Just one bite may initiate an allergic reaction,
and itching may persist up to 5 days after the bite. Fleas may also
serve as intermediary hosts of dog tapeworms. Cats or dogs may acquire
this intestinal parasite while grooming themselves by ingesting adult
fleas that contain a cyst of the tapeworm.
