Australasian Journal of Dermatology
David de Berker1 and Rodney Sinclair2
1Bristol Dermatology Centre, Bristol Royal Infirmary, Bristol, United Kingdom,
2Department of Dermatology, St. Vincent’s Hospital, Fitzroy, Victoria, Australia
into three categories: biological resistance to a range of chemical insecticides; practical and social problems with the
application of physical therapies; and re-infestation. It is
Dermatologists are the nominal experts in the
notable that Bailey and Prociv felt the last aspect was not
management of head lice in Australia, yet many
contributory to their protracted problem.
dermatologists infrequently treat patients with thiscondition. Most people are managed in the com-
munity by school nurses, local council health officers,pharmacists, paediatricians or general practitioners.
Reports of resistance began to emerge from all over the
Only a small number will present to the dermatologist
world4–12 soon after the introduction of insecticides for the
and commonly these patients will have tried a variety
treatment of head lice. In the 1980s, dichlorodiphenyl
of treatments and failed to respond. Resistance is
trichloroethane (DDT)4 was the first agent suspected, followed
reported to all of the currently available insecticide
by lindane5,6,12 and latterly malathion,6–12 permethrin6,12 and
treatments and this makes management of this com-
pyrethrins with piperonyl butoxide8 (Table 1). Some lice
mon community-acquired infestation more involved.
now appear to be multiply resistant, with levels of in vivo
Key words: cotrimoxazole, DDT, ivermectin, lin-
resistance to permethrin rising to 87% in an urban setting such
dane, malathion, pediculosis capitis, permethrin,
as Bristol, England, with coincident resistance to malathion
piperonyl butoxide, public health, pyrethrins, resis-
of 64%.12 These figures represent children undergoing
supervised applications by medical staff. Head lice harvestedfrom the same group of children were tested in vitro
to representative concentrations of both insecticides and to DDT and carbaryl. The patterns of resistance mimicked the clinical resistance in the first three, with only carbaryl
The article in this issue by Bailey and Prociv1 on head lice will
allowing survival of less than 5% of tested lice. Permethrin,
strike a familiar note with parents and doctors alike. Their
pyrethrins with piperonyl butoxide and malathion are avail-
account is similar to that given by another medical family
able over the counter in the United Kingdom (UK), as in many
other parts of the world, and these patterns of resistance are
The natural history of infestation has been described in a
volunteer to continuous exposure to lice bites.3 The sequence
Cotrimoxazole has been reported as an effective treatment
of skin reactions were: phase 1, no clinical symptoms; phase
for head lice.13 The putative mechanism of action is on
2, pruritic papules; phase 3, immediate wheal formation after
symbiotic Gram-negative bacteria in the gut of the louse that
bites, followed by an intensely itchy delayed papular eruption;
are required for digestion of ingested blood products.
phase 4, papular reaction with diminished skin reactivity and
Unfortunately, it is only effective against adult and nymphal
mild pruritus. Healed bite reactions reappeared when other
stages but not the eggs, so prolonged courses are required.14
parts of the skin were again exposed to lice.
Newer agents such as ivermectin15 may hold promise, but
Head lice are seldom cited as a health risk, but rather a
there are reports of fatal toxicity in veterinary use and a fear
source of domestic frustration and upheaval in the school,
of increased susceptibility to neurological side-effects in
home and doctor’s office. The difficulties in treatment fall
children.16 A 1% shampoo formulation warrants furtherinvestigation.17
However, the adaptability of head lice is well proven and it
Correspondence: Rodney Sinclair, Department of Dermatology, St
is likely that resistance will also develop in time to these new
Vincent’s Hospital, Fitzroy, Vic. 3065, Australia. Email: firstname.lastname@example.org
agents. It is this setting that makes physical treatments an
Rodney Sinclair, FACD. David de Berker, MRCP.
PHYSICAL THERAPIES AND THEIR
lence of infestation in those schools had risen.20 This could
represent a failure of the educational process, poor motivationwithin the family, or some other biological or social process
Physical therapies are legion and are poorly studied. They
resulting in increased infestation. Limited trials on a modest
utilize a range of approaches; the most popular is extraction
scale suggest that combing might work, but it may still be
of eggs and lice with a fine comb. Metal combs are better than
difficult to achieve success across the board.
plastic and it is useful to have a lubricant (such as conditioner)to assist clearing knots and to make the process more com-fortable. Combing regimens are not specific but are designed
RE-INFESTATION AND SCHOOL EXCLUSION
to remove mature lice which might otherwise lay eggs and
One modality that combines physical treatment and moti-
perpetuate the life cycle. If no adult lice have been found for
vation is school exclusion. This is common in schools in
2 weeks, it is likely that the cycle has been broken. Combing
Australia and the United States of America. For the strategy to
can be undertaken every one to 3 days.
be successful, all children in the class must be evaluated by
Although there are reputable claims that this method is
health professionals after the reporting of a single case. All
effective18 there are no good randomized or controlled trials.
those affected must be excluded. Exclusion could be overnight
As Bailey and Prociv point out, it is difficult to comb effectively
during treatment21 or for 2 weeks, depending on whether the
and to be sure that all the lice on the scalp are found when
aim is to ensure therapy or cure. Theoretically, re-admission
the hair is long and thick, and residual lice could easily result
is only after clearance has been confirmed by examination.
in treatment failure.1 Eighty percent of infestations represent
There is no recent evidence that exclusion is effective in
a load of only 1–10 lice, which means that it is easy to miss
controlling head lice in school children. Possibly this is
because it is difficult and expensive to fully enforce. Failure
Alternatives include killing the adults with an electric
is likely in areas of pharmacological resistance, where
comb that discharges a small shock, shaving the hair, or using
re-infestation occurs within the family or where motivation
agents such as petrolatum, olive oil or even mayonnaise that
is lacking and family order less defined. Some children could
suffocate the lice. To suffocate the lice, a generous quantity of
continue to be excluded for prolonged periods, based on social
grease is massaged into the scalp and over the hair. It is then
factors that reduce the chances of effective treatment. These
washed out over successive nights with shampoo. This is time
kinds of consideration must bring exclusion into question and
consuming, particularly when the hair is long or thick.
it has been challenged by some authorities.21
Petrolatum is, of course, not to be confused with petrol orkerosene; both have been advocated, but are dangerouslyflammable, a problem shared with alcohol-based topical
products that also have the potential for exacerbating asthma.
From the account of Bailey and Prociv,1 it seems that a
So what is the cost? There are the costs of chemicals, family
combination of shorter hair and diligent combing was
time, and potential social and educational costs. The pharma-
eventually successful. From the domestic angle, it is difficult
ceutical industry is likely to continue to produce new chem-
to get young children to be still for 20 min each, while the wet
icals that will gradually increase in cost and provide only
or lubricated hair is combed with a fine nit comb, a procedure
temporary benefit. Prescriptions for pediculocides in England
that may have to be repeated for weeks on end.
rose 500% between 1985 and 1995, reflecting a combination
In principal, shaving, petrolatum or combing might be 100%
of resistance and increased prevalence.22 Families are variable
effective. However, on a population basis, the results are less
in their ability to apply treatments, with a mixture of poor
encouraging. Twelve months after an educational programme
information and confusion complicating the situation. Sources
to describe ‘nit busting’ in local primary schools, the preva-
of clear information may not always be to hand for clinicianor patient (Table 2). The emerging patterns of resistance
Reports of insecticide resistance in the treatment of head
Sources of information on the Internet, including patient
Well balanced, comprehensive website useful to clinicians
Designed by an interest group with a heavy emphasis on
eradication. Contains an aggressive protocol for combing and
Background information and a good description of combing
‘Head lice’ search at this site yields several pages, includingprofessional notes and a multilingual patient information
DDT, Dichlorodiphenyl trichloroethane; Ref., reference number.
sheet. No mention of combing or insecticide resistance
International surveys of head lice infestation in school
2. Dawes M, Hicks NR, Fleminger M et al.
Treatment for head lice.
3. Mumcuoglu KY, Klaus S, Kafka D, Teiler M, Miller J. Clinical
observations related to head lice infestation. J. Am. Acad.
4. Sinniah B, Sinniah D. Resistance of head louse (Pediculus humanus
capitis de Geer
) to DDT in Malaysia. Trans. R. Soc. Trop. Med. Hyg.
5. Kucirka SA, Parish LC, Witkowski JA. The story of lindane
resistance and head lice. Int. J. Dermatol.
6. Goldsmid JM. Head louse treatment. Is there an insecticide
resistance problem? Med. J. Aust.
7. Rupes V, Moravec J, Chmela J, Ledvinka J, Zelenkova J. A
resistance of head lice (Pediculus capitis
) to permethrin in Czech
Republic. Cent. Eur. J. Public Health
: 30–2 (English
mean that last year’s literature may be misleading. Although
a systematic review23 concluded permethrin was the only drug
8. Burgess IF, Brown CM, Peock S, Kaufman J. Head lice resistant
to be supported on the basis of the evidence, it is also the drug
to pyrethroid insecticides in Britain. BMJ
for which there is most evidence of resistance. In this partic-
9. Mumcuoglu KY, Hemingway J, Miller J et al.
ular review, other drugs, such as carbaryl, were excluded
in the head louse Pediculus capitis
from Israel. Med. Vet. Entomol.
because of lack of studies, not evidence of lack of efficacy.23
10. Picollo MI, Vassena CV, Casadio AA, Massimo J, Zerba EN.
Can head lice spread serious diseases? Impetigo may be a
Laboratory studies of susceptibility and resistance to insecticides
complication. Where typhus is prevalent, as in some African
in Pediculus capitis
(Anoplura; Pediculidae). J. Med. Entomol.
countries, body lice may contain Rickettsia prowazekii
Although mentioned in a recent review,25 there is no modern
11. Pollack RJ, Kiszewski A, Armstrong P et al.
English language literature concerning head lice as a vector
susceptibility of head lice sampled in the United States and Borneo.Arch. Pediatr. Adolesc. Med.
for typhus or trench fever. To a great extent, the problem, if it
12. Downs AMR, Stafford KA, Harvey I, Coles GC. Evidence for
is a problem, is seen as one affecting the school and educa-
double resistance of permethrin and malathion in head lice.
tional process. Data from schools in different parts of the
Br. J. Dermatol.
world26–29 illustrate that infestation is common (Table 3).
13. Burns DA. Action of cotrimoxazole on head lice. Br. J. Dermatol.
Within Australian schools, infestation rates of 72% and zero
have been reported in separate classrooms of the same
14. Morsy TA, Ramadan NI, Mahmoud MS, Lashen AH. On the
efficacy of co-trimoxazole as an oral treatment for pediculosis
school.26 Perhaps the classroom is where the problem should
capitis infestation. J. Egypt. Soc. Parasitol.
be tackled. If the efficacy of combing could be established, in
15. Burkhart CG, Burkhart CN, Burkhart KM. An assessment of
endemic areas this cheap and non-toxic treatment could be
topical and oral prescription and over the counter treatments for
headlice. J. Am. Acad. Dermatol.
Until this becomes the case, an approach to treatment
16. Burkhart CN, Burkhart CG. Another look at ivermectin in the
could be an initial treatment with a pediculocide alone or
treatment of scabies and head lice. Int. J. Dermatol.
together with daily combing, depending on preference.30 The
17. Youssef MY, Sadaka HA, Eissa MM, el-Ariny AF. Topical appli-
pediculocide could be permethrin or malathion or pyrethrins
cation of ivermectin for human ectoparasites. Amer. J. Trop. Med.
with piperonyl butoxide, depending on local experience. If
there is treatment failure, a different pediculocide should
18. Lewendon G. Head lice can be controlled without application of
be used, with carbaryl representing the agent with least
insecticide lotions. BMJ
reported resistance. Alternatively, combing alone could be
19. Fan PC, Chung WC, Kuo CL et al.
Evaluation of efficacy of four
encouraged where the situation suggests that it will be done
pediculocides against head louse (Pediculus capitis
) infestation.Kao Hsiung I Hsueh Ko Hsueh Tsa Chih
diligently. In all cases, combing should be used as
20. Downs AMR, Stafford KE, Stewart Coles GC. Factors that may
part of scalp assessment and continued surveillance of the
influencing the prevalence of head lice in British school children.
affected child and other family members. In resistant cases,
cotrimoxazole or ivermectin can be used. Patients can be
21. Department of Human Services, Victoria.http://www.dhs.vic.gov.
referred to websites with reasonable advice, or material can
be downloaded for dissemination by the health professional
22. Harvard School of Public Health. http://www.hsph.harvard.edu/
(Table 2). This includes detailed advice on combing and treat-
23. Vander Stichele RH, Dezeure EM, Bogaert MG. Systematic review
ment of potential fomites. The latter are not a major problem
of clinical efficacy of topical treatments forhead lice. BMJ
and a hot wash of bedding linen and clothes should normally
24. Roux V, Raoult D. Body lice as tools for diagnosis and surveillance
of re-emerging diseases. J. Clin. Microbiol.
25. Chosidow O. Scabies and pediculosis. Lancet
26. Speare R, Buettner PG. Head lice in pupils of a primary school in
Australia and implications for control. Int. J. Dermatol.
1. Bailey A, Prociv P. Persistent head lice following multiple treat-
27. Downs AMR, Stafford KA, Coles GC. Head lice: Prevalence in
ments: Evidence for insecticide resistance in Pediculus humanus
schoolchildren and insecticide resistance. Parasitol. Today.
. Australas. J. Dermatol.
28. Hong HK, Kim CM, Lee JS, Lee WJ, Yang YC. Infestation rate of
) infestation among inhabitants of the Niger Delta. Trop.
head lice in primary school children in Inchon, Korea. Korean J.
: 243–4 (English abstract).
30. Therapeutic Guidelines Limited. Therapeutic Guidelines: Derma-
29. Arene FO, Ukaulor AL. Prevalence of head louse (Pediculus
, v.1. Melbourne: Therapeutic Guidelines Ltd, 1999.
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