Head lice

 

Head lice

General considerations

Most cases of head lice are asymptomatic. Head lice are detected when eggs are noticed in the hair, or when there is significant itching of the scalp and nape of the neck. Excoriations and papules can be present around the occiput and nape, and lymphadenopathy with or without secondary bacterial infection may occur.

Diagnosis of active lice infestation is confirmed by observing a moving louse. This can be achieved by wet combing. Apply a generous amount of hair conditioner to wet hair and comb with a fine-toothed comb (suitable combs are available from pharmacies). The conditioner stuns the lice and stops them crawling for about 20 minutes. Detangle the hair, divide into 3 to 4 cm sections, and comb each section. Wipe conditioner off the comb onto paper towel and look for lice and eggs (nits). In situations where head lice are common, repeat this method at regular intervals to detect head lice infestation.

Treatment

Wet combing can also be used to treat head lice (see method above; repeat daily until lice are not found); however, this method only has about a 40% success rate. Combing is easier with shorter hair styles, but shaving the head is not necessary.

The currently recommended topical insecticide treatments for head lice are:

1

maldison 0.5% topically, leave for 8 hours (not to be used for children younger than 6 months); repeat treatment in 7 days

OR

1

maldison 1% topically, leave for 30 minutes (not to be used for children younger than 6 months); repeat treatment in 7 days

OR

1

permethrin 1% topically, leave for a minimum of 10 minutes; repeat treatment in 7 days [Note 1]

OR

1

pyrethrins 0.165% + piperonyl butoxide 1.65% topically, leave for a minimum of 10 minutes; repeat treatment in 7 days.

Repeat head lice treatment in 7 days.

A number of proprietary products are marketed for the treatment of head lice; however, some do not contain one of the insecticides listed above.

Use the wet combing method the day after each treatment to check for live lice. If live lice are found despite treatment that has been correctly applied, the head lice are resistant to the product used (see Treatment failure).

In between treatments, use the same wet combing method twice, removing all eggs less than 1.5 cm from the scalp with the fine-toothed comb or by pulling them off with fingernails. The presence of eggs more than 1.5 cm from the scalp indicates previous, not active, infestation.

Wet combing should be repeated weekly for several weeks after cure to detect recurrence.

Wash pillow cases on hot cycle, and combs and brushes in hot water (60 C). Examine household members and close contacts and treat if live lice are found. When head lice are detected, notify the child’s school of the infestation. It is not necessary to exclude children from school after the initial treatment of head lice.

Treatment failure

Resistance to all topical insecticides is increasing, and can cause treatment failure. However, incorrectly applied treatment or re-infestation are also causes of treatment failure.

For head lice that are resistant to one of the recommended topical insecticides above, use:

1

a different topical insecticide from the list above

OR

2

the wet combing method (see above).

Occlusive products containing dimeticone have been used to treat head lice. While good quality data to support the use of dimeticone are lacking, it appears to be a safe alternative to topical insecticides without the risk of resistance, and may have a role when topical insecticides have failed. As with topical insecticides, repeat dimeticone application in 7 days.

If head lice are refractory to all of the treatments above, use:

ivermectin (adult and child 15 kg or more) 200 micrograms/kg orally with fatty food, as a single dose; repeat dose in 7 days

General considerations

Most cases of head lice (Pediculus humanus var. capitis) are asymptomatic. Head lice are detected when eggs are noticed in the hair, or when there is significant itching of the scalp and nape of the neck. Excoriations and papules can be present around the occiput and nape, and lymphadenopathy with or without secondary bacterial infection may occur.

Diagnosis of active lice infestation is confirmed by observing a moving louse. This can be achieved by wet combing. Apply a generous amount of hair conditioner to wet hair and comb with a fine-toothed comb (suitable combs are available from pharmacies). The conditioner stuns the lice and stops them crawling for about 20 minutes. Detangle the hair, divide into 3 to 4 cm sections, and comb each section. Wipe conditioner off the comb onto paper towel and look for lice and eggs (nits). In situations where head lice are common, repeat this method at regular intervals to detect head lice infestation.

Treatment

Wet combing can also be used to treat head lice (see method above; repeat daily until lice are not found); however, this method only has about a 40% success rate. Combing is easier with shorter hair styles, but shaving the head is not necessary.

The currently recommended topical insecticide treatments for head lice are:

1

maldison 0.5% topically, leave for 8 hours (not to be used for children younger than 6 months); repeat treatment in 7 days

OR

1

maldison 1% topically, leave for 30 minutes (not to be used for children younger than 6 months); repeat treatment in 7 days

OR

1

permethrin 1% topically, leave for a minimum of 10 minutes; repeat treatment in 7 days [Note 1]

OR

1

pyrethrins 0.165% + piperonyl butoxide 1.65% topically, leave for a minimum of 10 minutes; repeat treatment in 7 days.

Repeat head lice treatment in 7 days.

A number of proprietary products are marketed for the treatment of head lice; however, some do not contain one of the insecticides listed above.

Use the wet combing method the day after each treatment to check for live lice. If live lice are found despite treatment that has been correctly applied, the head lice are resistant to the product used (see Treatment failure).

In between treatments, use the same wet combing method twice, removing all eggs less than 1.5 cm from the scalp with the fine-toothed comb or by pulling them off with fingernails. The presence of eggs more than 1.5 cm from the scalp indicates previous, not active, infestation.

Wet combing should be repeated weekly for several weeks after cure to detect recurrence.

Wash pillow cases on hot cycle, and combs and brushes in hot water (60 C). Examine household members and close contacts and treat if live lice are found. When head lice are detected, notify the child’s school of the infestation. It is not necessary to exclude children from school after the initial treatment of head lice.

Treatment failure

Resistance to all topical insecticides is increasing, and can cause treatment failure. However, incorrectly applied treatment or re-infestation are also causes of treatment failure.

For head lice that are resistant to one of the recommended topical insecticides above, use:

1

a different topical insecticide from the list above

OR

2

the wet combing method (see above).

Occlusive products containing dimeticone have been used to treat head lice. While good quality data to support the use of dimeticone are lacking, it appears to be a safe alternative to topical insecticides without the risk of resistance, and may have a role when topical insecticides have failed. As with topical insecticides, repeat dimeticone application in 7 days.

If head lice are refractory to all of the treatments above, use:

ivermectin (adult and child 15 kg or more) 200 micrograms/kg orally with fatty food, as a single dose; repeat dose in 7 days [Note 2