A 25-year-old married male presented with itching in the
pubic area since two weeks. He gave a history of extramarital contact three
weeks ago. On examination he was found to have excoriated papules in lower
abdomen, pubic area and thighs. Close inspection revealed multiple brown
colored nits attached to the pubic hairs. A clinical diagnosis of phthiriasis
pubis was made. Other hair bearing areas including axilla, beard, mustache,
eyelids and scalp were examined and were found to be free from infestation. He
had no genital ulcer, urethral discharge or inguinal adenopathy. Serology for
syphilis and retroviral status were non reactive. Microscopic examination of
pubic hair revealed the presence of pubic louse with characteristic morphology
and a blood filled esophagus indicating a recent blood meal [Figure 1].
The Crab louse or Phthirus pubis is a
dorsoventrally flattened, wingless insect of order Anoplura and
familyPthiridae. Adult louse
measures about 1–2 mm with three parts namely head, thorax with three pairs of
legs, and abdomen. The terminal part of each leg has claw-like appendages whose
grasp is designed to match the diameter of pubic or axillary hair. The louse
buries sharp mouthpiece stylets inside the pubic hair follicle to obtain a
constant blood supply.[1]
Sexual transmission is considered the most
important means of crab louse transmission.[2] However, there are
documented cases of transmission from toilet seats, beds, and egg-infested
loose hairs dropped by infested persons on shared objects. Treatment options
include 1% permethrin rinse, 5% permethrin cream, 1% lindane shampoo, oral
ivermectin. Occlusive agents like vaseline, freshly prepared fluorescein
eyedrops and manual removal of nits are recommended in case the eyelashes are
infested.
Below: Crab louse with its characteristic morphology grasping the hair shaft with blood filled esophagus (40× magnification)
Via:
By:
Address
for correspondence: Dr. Arun Prasath
Palanisamy, Department of Dermatology and STD, Vinayaka Mission's Medical
College and Hospital, Karaikal - 609 609, Puducherry, India. E-mail: ni.oc.oohay@tri_lihumrd
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