Head Lice (Pediculosis capitis)

Dr. KS Prasanna, Director, Institute of Applied Dermatology, Kasaragod, Kerala

A beautiful crying girl accompanied by her mother to my OP the other day. I asked her mother, what is the problem? Why she is so sad and crying so much? Mother said “she had beautiful long hair. But just now, we went to the parlour and cut her hair despite her resistance, because I am not able to manage her hair due to head lice. It was her dream to have long hair. I am also pained to cut it, but I don`t have any other alternative, other than cutting her hair. When we take the treatment for one month, she is fine, again she gets this infection. Is there a permanent cure doctor?”. The cute little girl was looking at my face with anger still on her face.

Yes, head lice are found worldwide with all ages, gender, race, and socioeconomic class. Children between the age of 3-11years of age have the highest incidence, with the prevalence of as high as 60%. Infestation with head lice is more frequent in girls, probably due to long hair as well as the exchange of comb, brush, and other hair accessories such as clips, hairband, and rubber band, in addition to the close head-to-head contact in the school.

It is caused by a blood-sucking, wingless, six-legged insects called Pediculus humanus var capitis. It lives only on the hairs of the scalp. Head lice are spread by head-to-head contact as well as a fomite, helmet, bedding, clips, hat, headphones. etc. The head lice are a highly host-specific insect approximately the size of a sesame seed. These obligate human parasites feed on the blood of the host for approximately 4-6 hours. The female louse lives for 30 days, during which it lays between 5-10 eggs a day on the hair shaft. The oval egg capsule(nits) measure 0.8mm in length and are usually laid close to the scalp for warmth, in general eggs are located within 1cm of the scalp are unhatched. In warm climates however viable nits may be found 15cm or more from the scalp especially just above the neck. The nits are cemented to individual hairs through a proteinaceous material that closely resembles the amino acid constituents of the human hair shaft itself.

Intense itching of the scalp is a common symptom. The itching is due to the immunological reaction to the saliva and excreta of the louse. In reinfection, itching develops in 24-48 hours. Some people develop an infection with swelling on the nape of the neck. Patients present with low-grade fever and lymphadenopathy due to secondary bacterial infection. Diagnosis is made by the identification of adult lice or nits.

Medication that contains pyrethrin, permethrin, ivermectin, Spinosad, malathion, etc is toxic to lice. Wash your child`s hair with shampoo with no conditioner before using one of these treatments.

·       Pediculicides remain the mainstay of therapy. All the topical, as well as an oral preparation, should be done twice, one week apart to kill any nits that survived after the first treatment.

• All the family members should be treated together.
• Disinfect the bedsheet, comb, and other hair accessories like clip and rubber band.
• We need to physically remove the nits via combs with closely spaced teeth.
• Avoid sharing combs, brushes hats, and scarves.
• Don`t lie on beds, couches, or pillows that have been in contact with a person infected by head  lice.