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Head lice: School of thought

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Head lice: School of thought

With the new school term in full swing, pharmacies are likely to experience an increase in parents asking for advice on preventing and managing head lice infestations in their children.

 

Learning objectives

After reading this feature you should be able to:

• Identify the symptoms and treatment options for head lice
• Explain why outbreaks of head lice and other parasitic infections occur
• Advise customers who may be travelling to affected areas about the Zika virus.

 

Anyone can catch head lice but pre-school and primary school children and their families are most at risk.1

When children play together, their heads are likely to come into close contact, allowing lice to pass from one head to another. Head lice are white or grey-brown in colour and can range in size from a pinhead to a sesame seed. Parents may not be aware their child has a lice infestation, so they need to look out for the following:

• Lice on the scalp
Lice are difficult to spot because they are small, avoid light and move quickly, but they are often visible when the hair is separated. When fully grown, head lice can be 3mm in length. Lice usually spread through direct head-to-head contact but they can survive for a short period on clothing or other personal items. Lice cannot jump or fly from one person to another.

• Itching
Lice bite the skin to feed on the blood of the host. The saliva from these bites causes an allergic reaction, which may result in itching on the neck, scalp and ears. When a child has an infestation for the first time, itching may not occur for two to six weeks, depending on the child’s sensitivity and history of lice infestation.

Frequent itching can cause broken skin, which can result in sores on the scalp that can become infected. Parents should be advised to seek medical advice if:
• The skin becomes red, swollen or painful
• The lymph nodes in the neck become tender
• There is a fever of 38°C (100°F) or higher.

• Nits (lice eggs)
Nits are the egg cases from which the lice hatch. Attached to hair shafts, they are easiest to spot around the ears and the hairline of the neck. Empty nits are sometimes easier to spot because they are lighter in colour, but the presence of nits doesn’t always indicate that there is an active infestation.

 

A Hedrin ‘Check-Treat-Complete’ 30-minute educational module is available, written in partnership with experts and accredited by the Royal Pharmaceutical Society, so pharmacy staff can refresh their knowledge on head lice as part of their ongoing learning.

 

Treatment methods

The head lice treatment market has changed almost beyond recognition in the past 10 years, says Caroline Wheeler, marketing manager for Hedrin. “The old challenges of resistance associated with pesticides are no longer a problem with the newer products, as these physically kill the lice instead of poisoning them,” she says.

“Past head louse treatments have included insecticide-based products, herbal remedies and physically acting preparations. The current trend is towards physically acting products as potentially there is no resistance to these formulations.”

The two main treatment methods are lotions/sprays and wet combing.

Lotions and sprays (chemical removal)

There are a number of different lotions and sprays that can be applied to the scalp and hair to kill head lice2, including:
• Dimeticone 4% lotion – applied and left on for eight hours
• Dimeticone 4% spray gel – applied and left on for 15 minutes
• Mineral oil and dimeticone 4% lotion and spray – applied and left on for 15 minutes
• Permethrin 1% creme rinse – applied and left on for 10 minutes
• Isopropyl myristate and cyclomethicone solution – applied and left on for 10 minutes
• Isopropyl myristate and isopropyl alcohol mousse – applied and left on for 15 minutes.

“There is strong evidence that the head lice population already has, and continues to develop, resistance to the traditional pesticides, permethrin and malathion,” says Caroline Wheeler. “In part, this is a result of inappropriate and overuse of these agents over a long period. Non-pesticide treatments have been shown to be more effective than pesticides because lice have no known mechanism for developing resistance to them.”

Wet combing (mechanical removal)

Wet combing involves methodically combing wet hair with a fine-toothed head lice comb to remove the lice. The Primary Care Dermatology Society (PCDS) advises that this is undertaken for three to four sessions over two weeks. After shampooing and conditioning the hair, a detection comb should be used to comb the whole head and the hair rinsed again.

Wet combing should be repeated until no full-grown lice have been detected for three consecutive sessions. Current evidence suggests that wet combing is less effective than insecticide use.3

“Some parents prefer mechanical methods such as wet combing with conditioner, which must be done methodically and regularly over several weeks. Trials have shown these to be effective in up to 57 per cent of those treated,” says Wheeler.(4)

Wet combing has some potential drawbacks, says Elizabeth Brunton, deputy director, Insect Research & Development Ltd. “Many people use the wrong kit and most do not comb with enough intensity. You need a detection comb and you need to comb at least every four days for at least two weeks, maybe more.

“The main problem people encounter is removing a few lice, thinking they have done a good job, and then stopping. Customers really have to do a thorough job of getting right down to the skin with the comb, but not scratching it, and using repeated strokes over the same area,” she says. 

Alternative treatments

A number of products based on alternative approaches are currently available, although there is little clinical evidence to support their effectiveness. Elizabeth Brunton warns that herbal treatments have not been clinically tested in rigorous clinical trials. “Using a normal tea tree shampoo might reduce dandruff but it only makes lice cleaner and smell different,” she says.

“Also, many essential oils have the same mode of action as pesticides, so are often affected by resistance.”

Head lice protection/repellent preparations are also available but expert opinion is divided as to the evidence regarding their effectiveness.

Why do outbreaks occur?

Head lice outbreaks are very common because the lice can spread quite rapidly if a child isn’t treated straightaway and has close head-to-head contact with his or her friends.

“It is important that parents check their child’s hair regularly. A good way to remind parents is our ‘once a week, take a peek’ initiative,” says Caroline Wheeler. (See onceaweektakeapeek.co.uk)

Despite treatments improving greatly over the past decade, it is difficult to establish why some treatments sometimes appear to fail and some children are more prone to infections than others. Wheeler has a theory.

“We found that nearly one in 10 school children may have head lice at any time but it is difficult to say whether or not these numbers are changing on a UK-wide basis. Children are more prone to get head lice if they have a lot of contact with each other.

“Children aged from four to 11 years are most at risk, but no one is immune. Girls and women tend to be more prone as they tend to interact more closely with one another. There are unfortunately still a few myths which suggest that having head lice has something to do with personal hygiene. However, head lice can live on all types of hair and no preference exists between clean or dirty hair.”

Elizabeth Brunton suggests that some of the formulations that are available are becoming less effective, but admits it is difficult to say whether this is to do with treatments not being applied properly, not left on for long enough, or whether there has been some small change in the physiology of head lice that allows them to cope better with a physically acting formulation.

If a head lice treatment appears to fail, she suggests pharma-cists advise customers to use a detection comb a couple of days after the treatment is applied to check that there are no surviving head lice.

“If problems persist, consumers should change to a different product or method to see if that resolves the situation,” she says.

References

1. gov.uk/guidance/head-lice-pediculosis
2. nhs.uk/conditions/head-lice/pages/treatment.aspx
3. pcds.org.uk/clinical-guidance/pediculosis
4. Hill N, Moor G, Cameron MM et al. Single blind, randomised, comparative study of the Bug Buster kit and over-the-counter pediculicide treatments against head lice in the United Kingdom. British Medical Journal 2005, 331: 384-7
5. cdc.gov/zika/about/index.html

 

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