Head Lice: Independent Study – wet combing with a Bug Buster comb better than dry combing for detection

Independent study proves that wet combing with a Bug Buster comb greatly surpasses dry combing to diagnose head lice

Fine-tooth comb used

The 1998 Bug Buster® comb used by Lapeere et al, 2007, can be distinguished from other fine-tooth combs with square-cornered tooth shanks by the deeply bevelled leading edge of the teeth. The instruction to hold the bevelled side towards the scalp is embossed on the comb. Using action research methodology (1996-8) it was found by CHC researchers that the deep slant of the tooth resting against the scalp balances with the slim handle, and this ensures that the comb enters the hair at precisely the correct angle to slide under lice, which are often found in the roots (Ibarra et al, 2002a). Keeping gentle contact with the scalp for as long as possible, the comb is then drawn through to the tips of the hair. In wet combing, this action picks up lice, immobilised by moisture, in the path of the comb, with no dependence on seeing them in the hair.  Wiping both sides of the comb on paper towel between strokes removes the lice easily and allows both carer and child to inspect them whilst still motionless (Bug Buster Kit instructions 1998 onwards).

Study objective and location

Lapeere et al 2007, compared the reliability of Wet combing with conditioner (WCWC) with Dry combing (DC) and Visual inspection (VI) for the detection of head lice. The study was carried out in primary schools in Gent, Belgium.

Method and Results The 1998 Bug Buster (BB) comb was used for WCWC and DC. The procedure for WCWC is: Thorough wetting of hair | Conditioner | comb | Rinse | comb. At each combing, the hair is first straightened with a wide tooth comb and when it can be run freely through the hair, the BB comb is substituted.

The sensitivity of WCWC was found to be 1.25 times higher than DC and 2.47 times higher than VI (same day consecutive screening of 608 children; 3 different, blinded screening teams of volunteers trained at one information session). The procedures were timed from initiation (e.g. from wetting the hair in the case of WCWC), and it was found that the median time needed to detect the first louse in infested children was VI 2’54’, DC 2’02’ and WCWC 3’34’.

‘The detection rate of head lice is highest with WCWC in every category of sex, age, hair length, hair type and colour’ The sensitivity of WCWC in brown hair is 3.3 times higher than VI, whereas in fair hair it is 1.6 times higher than VI (Lapeere et al, 2007). The likely reason for this is that lice are more conspicuous in fair hair (Willems et al, 2005).

Study conclusion

It was concluded that WCWC should be the first choice for assessing the outcome in clinical trials of treatment products, and for use by parents and health providers, with DC as second best.

Comment

Bug Busting wet combing (BBWC) has not been directly compared with WCWC, but is likely to be a little more sensitive because shampooing ensures that lice at the roots of the hair are thoroughly wet. The procedure for BBWC is: Shampoo hair | Rinse | Conditioner |comb | Rinse | comb. At each combing, the hair is first straightened with a wide tooth comb and when it can be run freely through the hair, the BB comb is substituted. There is another method of ‘diagnostic wet combing’ (Jahnke et al 2009) in use for measuring trial outcomes and in some communities e.g. Australia, where there is no initial wetting of hair. ‘Leave-in’ conditioner (no rinsing out required) is applied to dry hair before fine-tooth combing.

This procedure is unlikely to be as sensitive as either WCWC or Bug Busting wet combing, firstly because less immobilising moisture may reach the lice at the roots of the hair, their main habitat. Secondly there is no failsafe second combing in the rinsed hair. This procedure is described as ‘conditioned combing (CC)’ by Lapeere 2007.

To access the full study report

You can find Lapeere H, Naeyaert J-M, De Bacquer D et al (2007) Diagnostic value of screening methods for head lice, in Lapeere H, ed. Development of an evidence-based management of pediculosis capitis and scabies.
Ghent University Hospital, Gent, Belgium 2007: 121–140
(PhD dissertation).

Click on https://biblio.ugent.be/publication/810574 and then scroll to Deel_3_Summary_research_papers.pdf pp 121–140. (2nd PDF down on the right hand side).

Updates on evidence and practical guidance on diagnosis, treatment and prevention are available from the NHS Clinical Knowledge Summary on head lice, accessible at:
https://cks.nice.org.uk/head-lice#!topicsummary