Treating head lice

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Editor, – I refer to Dr Orli Wargon's article 'Treating head lice' (Aust Prescr 2000;23:62-3). I was surprised by the recommendation that all clothes, head gear etc. be washed on the grounds that head lice can survive away from the host for three days and eggs can survive for 10 days.

I had understood this advice to be outdated on the basis that live lice which become detached from the head are at the end of their days anyway. Eggs should not be acquired from fomites as there is no glue to attach them to a hair shaft. Further, egg hatching is highly dependent on temperature and humidity with few eggs hatching at under 22°C. If a few do, they would need lottery-winning style luck to find a human for that all-important first blood meal.

Fraser M. Hadden

Editor, – Dr Orli Wargon's article 'Treating head lice' (Aust Prescr 2000;23:62-3) was useful, as this is a common problem which disrupts schools and disturbs parents, but it was not comprehensive enough in its approach.

Professor Richard Speare of James Cook University has conducted extensive tests to determine the effectiveness of current products on the market to treat head lice and has concluded that, while resistance is growing towards permethrin and maldison, those products containing pyrethrum together with aromatic oils and natural repellents not only kill the head lice, but also dissolve the glue that sticks them to the hair.1

This is advantageous for children with long hair, where fine-tooth combing with vinegar/water solution to remove the eggs after treatment is a painful experience. Herbal oils which dissolve the glue allow simple shampooing after treatment to remove the eggs.

A recent addition to the market is preventive headbands, cap inserts and scrunchies impregnated with pyrethrum, rosemary and citronella. These can be worn to school and discourage the spread of head lice by direct contact in much the same way as a dog flea collar!

Richard Lord
Narooma, NSW

Dr Orli Wargon, the author of 'Treating head lice', comments:

In reply to Dr F. Hadden, there are references to support washing clothes and headgear, for example, the most recent edition (1999) of Fitzpatrick's Dermatology in General Medicine (page 2683) which also refers (page 2681) to transmission by shared towels, brushes and combs playing a significant role.

Regarding Richard Lord's interesting letter, the textbook also mentions that natural pyrethrin products containing refined kerosene or petroleum distillates may cause eye irritation and that care must be exercised to avoid eye contact, but this is difficult in children. Other references mention using 30-40 g of standard petrolatum to the entire surface of the hair and scalp left overnight with a shower cap to clog the respiratory spiracles of the adult louse and block efficient air exchange.1 This, however, then requires 7-10 days of diligent shampooing to remove the residue.