PEDICULOSIS/ LICE INFESTATION

Lice are wingless, flattened, blood-sucking insects that are survive as surface parasites on birds and mammals.  

Pediculosis is a term used to denote infestation by Pediculus capitis  (head louse), Pediculus  humans (body  louse), or Phthirus  pubis (pubic louse). The bites of lice are painless and difficult to detect. The clinical signs and symptoms are the result of the patient’s reaction to the saliva and anticoagulant injected into the dermis by the louse at the time of feeding. Depending on the degree of sensitivity and previous exposure, the feeding sites produce reddish rash hours to days after feeding.

Itching (Pruritus) is the most common symptom of any type of pediculosis.

Lice cannot jump or fly. Pets are not vectors (carriers of insect). Diagnosis is made by seeing the lice or their eggs.

Lice feed approximately five times each day by piercing the skin with their claws, injecting irritating saliva, and sucking blood.

Lice are active and can travel very fast. That is why they can be transmitted so easily. The life cycle from egg to hatching of the insect, and then laying new egg is approximately 1 month.

NITS/LICE EGGS

The female lays approximately six eggs, or nits, each day for up to 1 month, and then dies. The louse incubates, hatches in 8 to 10 days, and reaches maturity in approximately 18 days. Nits are 0.8 mm long and are firmly cemented to the bases of hair shafts to close to the skin to acquire adequate for incubation. Nits are very difficult to remove from the hair shaft.

Clinical manifestations

Lice infestation of the scalp is most common in children. An average patient carries less than 20 adult lice. A small minority of patients can have more than 100 lice in the scalp. Scratching causes inflammation and secondary bacterial infection, with boils (pustules), crusting, and lumps in the neck (cervical lymphadenopathy).

The eyelashes may be involved, causing redness and swelling. Examination of the back of scalp shows few adult organisms but many nits. Nits are cemented to the hair, whereas dandruff scale can be easily moved along the hair shaft. Head lice can survive away from the human host for about 3 days, and nits can survive for up to 10 days.

Transmission

The main source of transmission is direct skin to skin contact. Other sources like hats, brushes, combs, earphones, bedding, furniture is common. Head lice do not carry or transmit any contagious infection.

Diagnosis

Lice are suspected when a patient complains of itching in a localized area without an apparent rash. The itching tends to very severe sometimes. Scalp and public lice will be apparent to those who carefully examine individual hairs. They are not apparent with only a cursory examination.

Finding nits does not indicate active infestation. Nits may persist for months after successful treatment. Live eggs reside within a quarter inch of the scalp.

COMBING

Combing the hair with a fine-toothed “nit,” or detection, comb is effective for detecting and removing live lice. The comb is inserted near the crown until it touches the scalp, and then drawn firmly down. The teeth of the comb should be 0.2 to 0.3 mm apart to trap lice. The entire head of hair should be examined for lice after each stroke. It usually takes 1 minute to find the first louse.

                                                    Lice and nits can be seen easily under a microscope and a hand lens.

Wood lamp examination

Live nits fluoresce and can be detected easily by Wood’s light examination, a technique that is especially useful for rapid examination of a large group of children. Nits that contain an unborn louse fluoresce white. Nits that are empty fluoresce gray.      

MANAGEMENT  STRATEGY

Infestation is most common among children 3-12 years of age and their parents. Identification of live lice is the gold standard of diagnosis; however, finding nits alone in a patient who has not been treated also warrants treatment.  Nits are easier to spot, especially at the nape of the neck and behind the ears. Hatched nits are white; unhatched nits are brown. Detection combing of wet hair with a fine-toothed  nit comb allows for efficient recovery of lice and nits for diagnosis.

Examination for nits and lice via nit combing

Nit combing is four times more efficient than and twice as fast as direct visual inspection.

FIRST-LINE THERAPIES

·         Malathion 0.5% lotion

·         Permethrin 1% cream rinse

·         Carbaryl  0.5% lotion

OTHER THERAPIES

Ø  Topical  crotamiton 10%

Ø  Nit picking

-          Bug Busting (wet combing)

Ø  Lindane 1%

Ø  Oral Ivermection

Ø  Topical lvermection

Ø  Trimethoprim /Sulfamethoxazole

Ø  Levamisole

Ø  Fomite control

Ø  Head shaving

Launderable items (worn clothing and used bedding, towels, scarves, and hats) should be placed in a dryer at 60°C for 10 minutes. Brushes, combs, and hair ornaments can be placed in hot water (60°C or more) for 10 minutes. Non-launderable   items (i.e, certain stuffed animals) should be placed in a bag for 3 days (not 15 days, as eggs laid off a host will probably not hatch close enough to a host to obtain their first blood meals).

Cloth furniture and rugs should be vacuumed. Fumigation of the home is not required.

Contacts of all detected cases, including classmates, should be screened. Empiric therapy for close household contacts is also recommended. Those likely to have had head-to head contact with the index case in the previous 4-6 weeks should be identified and screened. Children should not be excluded from school for head lice as the infestation often has been around for month prior to its detection. Hair grows 1cm per month, and lice lay eggs close to the scalp where it is moist and warm. Nits detected 2 cm from the scalp represent a 2 months old infestation. Therapy within a week of the detected infestation is more reasonable.

Dr Arika Sethi

Dr Pradeep Sethi

http://www.directhairtransplantation.com