Case #292 – February, 2011

Upon returning from a week-long business trip to Las Vegas, a 35-year-old man found what appeared to be insects among various articles of clothing. Due to the recent heightened awareness of bed bugs in hotels, he decided to bring the insects to the local extension office for identification help. The specimens, which measured on average 2 mm in length, were cleared and mounted in balsam for identification by the state entomologist. Figures A and B show two of the specimens. What is your diagnosis? Based on what criteria?

Figure A

Figure B

The organisms shown in this case were the pubic louse, Pthirus pubis. Diagnostic morphologic features included:

a size range compatible with P. pubis.
the presence of six legs ending with tarsi adapted for gripping hair shafts.
the presence of antennae, which ruled-out ticks and mites.

The specimen in Figure B was a gravid female, as an egg could be seen within her body (arrow, Figure B).

Figure B