Head lice
A Summary of The Guidance by The Public Health Medicine Environmental Group
1. Detection
The old-fashioned system of mass head checks is not effective in detecting small numbers of lice - parents are now in the "front line" of head louse detection.
To perform this task effectively they need informed advice from healthcare professionals and a fine-toothed detector comb: the sequence is as follows:
- Make sure you have plenty of light - ideally daylight
- Wash the hair with ordinary shampoo and towel it until it is damp but not dripping.
- Comb damp hair with an ordinary comb to remove the tangles...
- ...then touch the teeth of the detection comb to the skin of the scalp at the cop of the head and draw the comb carefully to the edge of the hair, keeping the teeth of the detection comb in contact with the scalp at all times.
- Do this over and over again, working round the head - it should take about 10-15 minutes to do properly.
- After each stroke look closely at the teeth of the comb for lice.
- It may help to rub conditioner into the hair before it is combed to make the combing easier; if so, use a tissue to wipe the conditioner off the comb and look for lice in it.
- If lice are present, you will see them - they are often not much bigger than a pinhead, but can be the size of a sesame seed.
Though this procedure may seem complex to parents at first, it can quickly become routine.
If living moving lice are found, infection is confirmed - the next step is to identify associated cases.
2. Contact Tracing
This is as vital as correct detection - failure to contact trace effectively can lead to re-infection.
Immediate family and close friends are the most likely sources of infection - people who have direct sustained head-to-head contact. These should be checked by detection combing. All confirmed cases should then be treated at the same time.
3. Treatment
Treatment should not take place unless a living, moving louse has been found, or a recovered louse is presented to the doctor, nurse or pharmacist - hearsay or unsupported concern is not sufficient reason for treatment.
Chemical insecticides - Malathion, carbaril (carbaryl) and the pyrethroids - are the only methods which have been scientifically demonstrated to be effective in the community. Chemical treatments will only be effective if applied adequately and appropriately.
Treatment methodology
Confirming British National Formulatory recommendations, the guidance states that two 12 hour or overnight chemical applications, 7 days apart, constitute one treatment.
Two applications are necessary to break the life cycle of the louse, the second application killing lice hatched from eggs unharmed by the lirst application before they have a chance to lay eggs of their own.
Treatment formulations
Water based liquids are effective and can be used on all patients from 6 months to adult.
Alcohol-based lotions are effective but are contraindicated for people with asthma or eczema and should be used in ventilated spaces. (Care should be taken to avoid naked flames)
Insecticidal shampoos are not effective and are not recommended in the guidance.
4. Treatment Failure
Though some treatment failures have been reported, so-called "resistance" may well be due to poor application methods, failure to identify and treat all infected contacts, subsequent re-infection, mistaken diagnosis of nits or itching as a continuing infection or a futile attempt to treat "imaginary" lice as a result of alert letters or rumoured infections.
Treatment should only be judged a failure after proper professional assessment of the case - as the causes listed above may well be responsible rather than true resistance to insecticides.
A step-by-step analysis after the apparent failure of a chemical treatment is therefore necessary before prescribing or recommending a different or repeat treatment.
Direct supervision of the application may be necessary to ensure that the treatment has the potential to be effective.
5. Insecticide Safety
The guidance states that the three insecticide groups have a good safety record over many years of use - humans metabolise the current insecticides much more rapidly than lice, so a lethal dose to a louse is practically harmless to a human.
Indeed, in over 25 years of use, there have only been 26 reported side effects to malathion with just 18 individuals affected. (Correct at May 1998)
6. Nostrums and Potions
"Alternative" head louse treatments ranging from tea tree oil to petrol have received publicity recently, - the guidance states categorically that these should not be used.
Their saftey profiles have not been evaluated fully and some - like petrol - are potentially lethal.
7. Rotational and Mosaic Policies
The guidance raises several objections to rotational policy including the loss of Health Authority control over distribution and doubts about the scientific grounds for single-insecticide treatment over a period of years.
Instead of rotation they now support a "mosaic" policy which involves changing active ingredients on an individual basis.
For instance, if a pyrethroid is used and professional assessment confirms that the treatment has failed, the doctor, nurse or pharmacist may suggest malathion - and if the infection persists, the doctor may prescibe carbaril (carbaryl).
The guidance also states that prescribing of head louse treatments should continue, just as prescriptions continue for antibiotics.
8. Wet Combing
Some people recommend wet combing with or without conditioner as a sole treatment for the head louse, but the guidance states that there is no authoritative evidence for its effectiveness at a community level.
However, wet combing is a good method of detection.
9. Advice and Support
The guidance states that schools should let head louse control became the community's responsibility, putting parents and primary healthcare staff at the front line.
Since many head louse treatments are bought over the counter, pharmacy staff are as vital a source of information to the public as nurses and doctors.
All primary healthcare staff need to be fully informed of the best methods of louse detection, contact tracing and treatment and pass these on to their patients.
This is only a brief summary of the point covered in the guidance - for further information, please contact your local Consultant in Communicable Disease Control (CCDC).