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DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/lice/.
Pthiriasis
[Pthirus pubis]
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Pthirus pubis, adults and nymphs.
Adult pubic lice (Pthirus pubis) measure 1.5-2.0 mm long and are dorsoventrally-flattened. Adults are much broader in comparison to head and body lice. The second and third legs have a large modified claw with a thumb-like projection, used for grasping on to hair shafts. Nymphs resemble the adults but are smaller; there are three nymphal stages in the life cycle of P. pubis. Adults and nymphs require human blood and are found only on the human host; although they are most-commonly found in the pubic and perianal regions, they may also be found on armpit, mustache, and chest hairs.
Figure A: Adult female P. pubis. An egg can be seen within her body cavity.
Figure B: Adult male of P. pubis.
Figure C: Three specimens of P. pubis on a hair shaft.
Figure D: Nymph of P. pubis.
Pthirus pubis, eggs (nits).
Eggs (nits) of pubic lice (Pthirus pubis) are under 1 mm in length, dark brown in color and opalescent. Eggs are glued to a hair shaft. Eggs take about one week to hatch.
Figure A: Egg (nit) of P. pubis.
