Response to Commentary on:
Head lice: boring for doctors, important to patients
Bailey AM
& H. Phillip Petersen. Head
lice: update on biology and control. (electronic
response letter) eBMJ 12 June 2003
Head Lice: update on biology and control 12 June 2003
*Anita M. Bailey & H.
Phillip Petersen,
*Independent researcher
C/O Microbiology & Parasitology
Dpt,
University
of Queensland, St Lucia 4072, Australia
Email Anita M. Bailey, et
al.: hlresearch@iprimus.com.au
Editor, recent lice articles, including 'BestTreatments'1,
need updating. Without serious medical investigation, head lice advice has
sometimes relied on speculation from a few entomologists. For example, advice
to avoid hair-cutting originated from a well-meaning but baseless suggestion in
the 1970's.
Resistance to pediculicides is well-documented.
Over-reliance on insecticidal treatment is putting
children's health at risk. Non-drug measures should be recommended. Unchecked
transmission in schools is causing higher prevalence. Routine screening is
advised. Without it, treatment decisions should take into account repeated
exposure.2,3
Head lice are not harmless. They can cause dermal injury and
sensitization. Some people resort to household poisons to relieve persistent cases.
A disproportionate amount of family time and money is wasted. Millions are
spent in each of the UK,
USA and Australia
on louse treatment annually.3
Detection and removal of lice in some hairstyles is more
difficult than previously thought. Our group has confirmed life-stage sizes as
small as 0.6mm. Louse camouflage and various hair factors can cause false
negatives and underestimations. Without such knowledge, clinical product assessments
are questionable.4
Those who use a tiered diagnostic approach to screening have
found that manual treatment is more successful than chemical. Fine-toothed
combing is so helpful that it is one of the tools by which therapies are better
assessed. Perhaps only head-shaving and microscopic examination are the gold standard.2,3,4
Dry-hair parting with a lamp-magnifier can help
practitioners to identify continuous egg deposition at the scalp-hair margin
outwards of chronic cases. Old 'nit' removal facilitates examination. Patients
who remove eggs may also find hidden lice. Further fine-combing may helpfully confirm
the live lice.2,3,4
Removed head lice are alive but probably less of a concern
than direct transmission or unrecognized relapses. Longer or thicker hair
impedes detection and removal of resistant infestations. Hair-shortening
improves comfort and access to residual lice. Pediculosis is not self-limiting
and undetected failures (some relapsing monthly for years) are common in longer
hair of girls.3
Lice can transfer instantly across hair tresses with a vigorous
rub. Severely neglected head lice may also bite further down the body. New
biological findings place head and body lice in the same species. Body lice
carry typhus, relapsing fever and trench fever, which are reemerging overseas.
We suggest that pediculicides should be reserved to assist with control of such
outbreaks. Lack of thorough screening and treatment will allow more resistant
lice to proliferate.5
1.
Nash B. Treating
head lice BMJ 2003; 326: 1256-8.
2.
Bailey AM, Prociv P. Persistent head lice
following multiple treatments: Evidence for insecticide resistance in Pediculus
humanus capitis. Australas J Dermatol
2000; 41: 250-54.
3.
Bailey AM, Prociv P. Pediculus humanus capitis infestations in the
community: A pilot study into transmission, treatment and factors affecting
control. Australian Infection Control 2001; 6: 95-101.
4.
Bailey AM, Prociv P. Head lice appearance and behaviour:
implications for epidemiology and control. Australian Infection Control 2002;
7: 62-71.
5.
Bailey AM, Prociv P, Petersen HP. 2003.
Head lice and body lice: shared traits invalidate assumptions about
evolutionary and medical distinctions. Australian Journal of Medical Science
2003; 24: 48-62.
Competing interests: None declared
