This is indeed a flea, an insect of the order Siphonaptera. Adult fleas are characterized by their laterally flattened wingless bodies, long legs designed for jumping, and tube-like mouthparts for feeding on blood from their host. The presence of both genal and pronotal combs (shown below) with more than 5 "teeth" on the genal comb allow this flea to be identified as either Ctenocephalides felis or C. canis, the cat and dog flea respectively. Identification to the species level is based on more subtle characteristics of the hind tibiae and head.
For some additional Flea Fun, check out this YouTube video that shows how fleas jump using their "feet" rather than their "knees."
Of interest, knowing whether or not the patient has dogs or cats in their house does not help in differentiating between C. felis and C. canis since they can both feed on either host.
When Ctenocephalides felis and C. canis are ingested - usually accidentally - they can transmit the tapeworm, Dipylidium caninum.
And now, our poem from Blaine Mathison:
Ctenocephalides is known as the cat flea
and among Garfield’s fur lives so happily
but be careful not to ingest
this siphonapteran pest
or you’ll find D. caninum proglottids in your poopie