Cathy Cooke shares the latest advice for pharmacists to share with patients on this common lice infestation
Key learning points
Requests for advice and treatment for head lice infestation are a regular occurrence in community pharmacy. Parents finding evidence of lice on their child for the first time are often shocked and embarrassed.
Therefore, the provision of accurate, practical information can reassure and help with effective treatment of the individuals, as well as contributing to the control of infestation in the wider community. The current prevalence of infestation in the UK isn’t accurately known, but historic data1 suggested between four and 22% of school age children could be affected at any one time.
A wingless insect 1 to 3 mm long, the ectoparasite Pediculus humanus capitis spends its entire life on the human head, feeding several times a day exclusively on blood. The eggs are oval, translucent and firmly attached with a glue-like substance to hairs, close to the scalp.
When the eggs hatch after about seven to 10 days, the empty egg cases (nits) become yellowish white and are more noticeable. The immature lice (nymphs) take a further seven to 10 days to mature into adults, when they start to reproduce, with females laying up to eight eggs a day. Adult lice have a lifespan of about 30 days. 1-3
Head lice can neither fly nor jump. The mode of transmission is thought to be almost entirely by head to head contact. They can live for a short period off the human head; estimates vary within the range 12 to 48 hours, so if they become dislodged transfer is possible via direct contact with inanimate objects such as shared headgear. 1,2
Although head lice infestation can affect people of any age, it is most common in children of primary school age (four to 11 years) with a peak at seven to eight years. 1-3
Evidence on risk factors comes from a Belgian study4 investigating the independent association between characteristics of the child, family socio-economic status and head lice. The authors identified hair length, hair colour, socio-economic status and the number of children in the family as the only statistically significant factors for head lice in children.
Hair length and colour may relate to the difficulty of treating long hair and of noticing signs of infestation. Larger families may face practical difficulties in checking and treating all children. The requirement to purchase treatment products can disadvantage families of low socio-economic status.
Clustering of children, such as in large families or in class at school, was judged to have more influence on prevalence compared with characteristics such as hair length or socio-economic status.
Head lice infestation commonly presents when nits or adult lice are spotted, or with itching. The presence of nits alone does not confirm a current infestation, as the empty egg cases remain firmly attached to the hair shafts and persist following eradication of lice.
Itching usually develops between two to six weeks after first exposure to feeding lice, typically from an immune-mediated hypersensitivity reaction. In the event of a future infestation, itching can develop in one to two days from exposure.
Pharmacists should advise patients to use a fine-toothed plastic detection comb, with teeth 0.2 to 0.3mm apart, to confirm the presence of lice. Dry combing or wet combing can be used for detection; wet combing with conditioner has the advantage that the conditioner immobilises the lice so they are easy to see on the comb.
When infestation has been confirmed by the presence of a live louse, treatment can be started. All affected members of the household should be treated at the same time. There is limited evidence on the effectiveness of different head lice treatments and no clear superiority of one method, so factors such as contraindications, cautions, individual choice and previous product or method used should be considered.
Compliance with treatment instructions is important for optimising its effectiveness, so ensuring that the customer understands the regime and the need to complete all stages, including checking the success of the treatment, is a key intervention.
There are three treatment options available:
There are advantages and disadvantages for each option but wet combing or dimeticone 4% lotion is recommended as first-line choice for:
Detection combing should be carried out to check if treatment was successful. With insecticides, recommendations vary on the frequency of detection combing. One regimen is to check two to three days after treatment and again seven days later; another suggests checking at days five, nine and 12 to 13 after the first application. With wet combing, a fifth session is carried out on day 17.
If there is treatment failure, check that the relevant procedure was followed correctly. The same treatment can be repeated but used accurately, or a different treatment option can be tried.
Prevention measures are generally of limited success. Keeping long hair tied back and regular combing with a fine-toothed comb may help. Don’t use insecticides for prevention.
Further information and patient leaflets
Cathy Cooke is a clinical pharmacist with experience of community pharmacy, primary care, urgent care, social care, secure environments.