Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial

Since publication of the report of our clinical study using 4%
dimeticone lotion to treat head louse infestation,[1] I have received
numerous enquiries about just how dimeticone fits in with current
approaches to head louse treatment. More recently I have been made aware
of a related debate that has circulated amongst members of the Public
Health Environmental Group (PHMEG) and has also been raised by several of
the local Minor Ailment and Pharmacist prescribing schemes.

The questions centre upon two points:

1.When the Stafford Group reported to the PHMEG [2] it was at a time
when scientific interest in head lice was still in the doldrums and many
of the guidance points included were based on experience, common sense,
and the best of the older literature.

There was little direct guidance on treatment, other than that what
evidence was available indicated that insecticides had a higher level of
evidence in their favour than otherwise and there were no or fewer
alternative options.

It was also advised, for example, that treatments should not be
applied further down long hair than the positioning of a ponytail band
simply because the authors agreed that a single 50mL bottle should be
spread no further and that under normal circumstances lice would not be
found far away from the scalp.

However, when we used 4% dimeticone we found that the highly mobile
fluid spread along hair shafts and lice “fled” from it, moving away from
the scalp necessitating application of the product to the tips of the
hairs. We found a similar effect, but to a lesser degree, with the
aqueous phenothrin comparator meaning that the guidance requires some
updating at least in that respect.

We also found that some guidance on quantities of product used are
required as the doses we had used to obtain an adequate coverage and a
good therapeutic effect were greater than any previous investigators had
indicated.[1]

2.When several of the Minor Ailment Pharmacy prescribing schemes were
set up, I was asked to provide introductory guidance for staff involved,
including sessions on louse biology and treatment. At the time the best
guidance I was able to offer on insecticide treatment was based on what we
could determine from in vitro studies, determination of resistance
distribution patterns, and latterly from the one clinical study of the
time comparing malathion with wet combing.[3]

That evidence suggested the treatment most likely to be successful in
dealing with most head louse infestations was alcoholic malathion lotion.
As a result, several of the schemes adopted this formulation as their
first line treatment option. Where alcoholic malathion failed, or where
it was unsuitable for a patient, different options were adopted by
different groups, none of which offered a clear solution to the problem.

How does 4% dimeticone fit into the current prescribing schemes? The
answer is that it offers an alternative option for treatment.

Where that option is placed is a matter for local policy makers.
However, as we stated in our report, the product is odourless and non
irritant and will not be affected by resistance to conventional
insecticides.[1]

Since some of the products most favoured by prescribers for those
with sensitive skin and asthma appear to be those most likely to fail due
to insecticide resistance [4] it would seem reasonable that this factor
should be a starting point for those deciding policies related to head
louse treatment, and they should also consider it as an alternative that
may help reduce the overall prevalence of lice by reducing some of the
risks of treatment failure for those families with longer term
infestations.

Irrespective of policy, it will be the public who will ultimately
guide the decision making process by buying treatment over the counter.
Most are prepared to try something new, especially if they have already
experienced large-scale treatment failure with other medications.

Ian F Burgess

ian@insectresearch.com

References

1.Burgess IF, Brown CM, Lee PN. Treatment of head louse infestation
with 4% dimeticone lotion: randomised controlled equivalence trial BMJ.
2005; 330 (7505): 1423-5

2.Stafford Group. Head lice: evidence-based guidelines based on the
Stafford Report. J Fam Health Care. 2002; 12 (Suppl): 1-21.

3.Roberts RJ, Casey D, Morgan DA, Petrovic M. Comparison of wet
combing with malathion for treatment of head lice in the UK: a pragmatic
randomized controlled trial. Lancet. 2000; 356:540-44.

4.Hill N, Moor G, Cameron MM, Butlin A, Preston S, Williamson MS,
Bass C. Single blind, randomised, comparative study of the Bug Buster kit
and over the counter pediculicide treatments against head lice in the
United Kingdom. BMJ. 2005; 331: 384-7.

Competing interests:
IB is a consultant to various companies making pediculicides and combs

There are many combing methods in current use for the detection and
treatment of head lice. In comparisons of their effectiveness it is
necessary to be precise. Burgess, Brown and Lee do not state how many
of their trial participants had been provided with a genuine Bug Buster
Kit (www.chc.org) with which to undertake wet combing.(1) A Bug Buster Kit
contains all the appropriate combs and step by step illustrated
instructions for their use plus essential information on breaking the
life-cycle by methodical louse removal, e.g. that the incubation period of
the egg can last 10 days. It cannot be supposed that parents told to use
a ‘nit comb’ with conditioner are testing bug busting wet combing. Also,
Burgess, Brown and Lee are mistaken in thinking that the Kit was submitted
to trial by De Maeseneer and colleagues.(2) The Belgian observational
study used a derivative of the bug busting wet combing protocol, adapted
for mass screening in school, where hair wetting was substituted for hair
washing.(3)

For measuring the outcome of treatment the most sensitive method
should
be used. It remains to be proved in a scientifically designed trial
that combing dry hair with a fine-tooth comb is superior to using a Bug
Buster comb according to the manufacturer’s instructions.

Moreover, without a co-ordinated programme to detect asymptomatic
cases
and treat them at the same time as obvious cases, the recommended
‘whole school approach’, described in the Department of Health leaflet
‘The Prevention and Treatment of Head Lice’(4), much expenditure of
professional and parental time and on products, is wasted.

Community Hygiene Concern, Reg Charity No: 801371
www.chc.org
bugbusters2k@yahoo.co.uk

References

1 Burgess IF, Brown CM, Lee PN. Treatment of head louse infestation
with 4% dimeticone lotion: randomised controlled equivalence trial.
BMJ, doi:10.1136/bmj.38497.506481.8F(10 June 2005).

2 De Maeseneer J, Blokland I, Willems S, Vander Stichele R,
Meersschaut F. Wet combing versus traditional scalp inspection to detect
head lice in schoolchildren: observational study. BMJ 2000;321:1187-1188.

3 Fry F, Ibarra J, Smith J, Wickenden C. Wet combing to eradicate
head lice. J R Soc Med. 2002;95:630-1.

4 www.dh.gov.uk/assetRoot/04/07/59/63/04075963.pdf; available free to
schools from: Department of Health, PO Box 777, London SE1 6XH
(Email:doh@prolog.uk.com)

Competing interests: Community Hygiene Concern is a charity, part-
funded by sales of the Bug Buster Kit on a non-profit making basis.

Competing interests:
Community Hygiene Concern is a charity, part-funded by sales of the Bug Buster Kit on a non-profit making basis.

There is always some uncertainty about the sensitivity of any
methodology used for assessment of head louse infestation. Curiously this
infestation is one of the few infectious conditions in which absolute cure
could possibly be determined. However, purity of results must be
subservient to ethical considerations, especially in paediatric studies.

We cannot imagine any ethics committee granting authorisation for a
study in which every participant is effectively cured prior to admission,
and then being reinfected, just so investigators could demonstrate exactly
how many insects were killed by yet another intervention. Also we can
just envisage the look on the faces of some of the parents of our
participants had we proposed to reapply the several hundred, or sometimes
thousands, of lice that would have been removed from their children had we
gone down this path. In a few cases it would have taken all day just to
count the lice from children who were reportedly regularly treated using
the bug busting wet combing method of treatment prior to enrolment in the
study.

If the Lice Snatcher is only as effective as the Bug Buster kit, as
reported by Ms Olsen, it would not have improved the sensitivity of our
detection method as the one trial of Bug busting as a detection method (1)
showed poor sensitivity compared with scalp inspection (2), which in turn
has been shown to be less sensitive than dry combing (3).

Ian F Burgess, Christine M Brown, Peter N Lee.

References:

1. De Maeseneer J, Blokland I, Willems S, Vander Stichele R,
Meersschaut F. Wet combing versus traditional scalp inspection to detect
head lice in schoolchildren: observational study. BMJ 2000; 321: 1187-8.

2. Berger MY, Bueving HJ, Konig S, Schouten BWV. Wet combing no
better than classical scalp inspection to detect head lice. BMJ
http://bmj.bmjjournals.com/cgi/eletters/321/7270/1187#11085 (1 December
2000)

3. Mumcuoglu KY, Friger M, Ioffe-Uspensky I, Ben-Ishai F, Miller J.
Louse comb versus direct visual examination for the diagnosis of head
louse infestations. Pediatr Dermatol 2001; 18: 9-12.

Competing interests:
IFB has been a consultant to various makers of pharmaceutical products, alternative therapies, and combs for treating louse infestations. PNL has analysed similar studies for other pharmaceutical companies.