Answer to Case 55
This was a case of tungiasis caused by Tunga penetrans, sometimes called a chigoe flea or jigger flea.  The inseminated female flea is about one millimeter in length.  She burrows into the skin of the feet or lower legs, often on or between the toes, and feeds on blood.  In the skin, the flea is oriented with her head facing away from the skin surface and her posterior end is sometimes visible as the characteristic black dot in the center of the lesion.  The flea both breathes and discharges waste and eggs from the posterior end.  After two weeks, the gravid female flea grows to a length of three to five millimeters and begins to discharge eggs.  The eggs hatch and the larvae develop into adults in about three weeks.  After copulation, the female flea searches for a warm-blooded mammalian host to which it will attach.  If it does not find a suitable host it will die.  Diagnostic features observed were:

• Typical painful, swollen lesion with a black center.
• Presence of flea as evidenced by legs and eggs embedded in tissue (Figures B, C, and D)

For more information about T. penetrans and to see an image of an adult flea, you may wish to visit the Ohio State University Web site at http://www.biosci.ohio-state.edu/~parasite/tunga.html.