Xenopsylla Cheopis - The Oriental Rat Flea

This male Xenopsylla cheopis (oriental rat flea) is engorged with blood. Note the actual size of the flea (at the top of the photo) compared with the enlarged insect.

The oriental rat flea is the primary vector of plague (the "Black Death").  Male and female fleas can transmit the infection.

Credits

Photo, Center for Disease Control