Fine combing of wet hair is far more effective than pharmacy-bought chemical lotions for eliminating head lice, say researchers.

People who used wet combing were four times more likely to rid themselves of head lice than those who used insecticide products, they found.

Head lice have developed resistance to common over the counter products.

The London School of Hygiene and Tropical Medicine research is published in the British Medical Journal.

Delousing

Head lice live close to the scalp, where there is warmth, food and shelter.

They cannot fly, jump or hop and are spread when people's heads touch each other.

To reproduce, they lay eggs that stick to the hair and hatch baby lice.

If the adult lice are removed from the head they cannot survive for more than about 24 hours.

Wet combing works by removing the adult lice, thereby stopping them laying any more eggs which should eventually stop the infestation.

Chemical lotions work by killing the adult lice and unhatched eggs.

However, neither treatment is 100% effective all of the time.

Frequent, repeated use of insecticide products is not recommended and lice are beginning to develop resistance to these chemicals, called pediculicides.

Head to head

Nigel Hill and his team asked the parents of 126 children aged 2-15 with head louse infestations to use pharmacy-bought insecticide products or the wet combing method, called Bug Busting, after washing the hair with normal shampoo and conditioner.

Overall, 56 of the children were treated using the Bug Busting method and 70 using over-the-counter delousing products.

The researchers then checked how many still had head lice two to four days after the volunteers had finished their treatment.

The cure rate of the Bug Busting method was far higher than that of the chemical treatment - 57% compared to 13%.

The authors said: "For every two or three people using the Bug Buster kit rather than pediculicides an extra person would be cured."

However, only one dose of insecticide was used in the study as recommended by manufacturers.

Need for new treatments

In the UK, experts generally recommend a further dose is used a week later to catch any eggs that evaded the first treatment and have hatched.

A past study showed this double dose had a cure rate nearer 80%.

Also, the current study authors said the Bug Busting's cure rate of 57% may still be too low to provide an efficient treatment against head lice.

"At present there are no readily available products that provide fully effective control of head lice and there is an urgent need," they said.

Dr Richard Roberts, consultant in clinical disease control at the National Public Health Service for Wales, said: "This shows that Bug Busting can work.

"To treat head lice, you need a mixture of treatments. It depends on the parent."

He said some parents might get on better using the lotions, while others who have more time to dedicate to combing out the lice, which can take up to half an hour if the child has very long hair, might prefer non-chemical Bug Busting.

Also, pregnant women and children under the age of one should not use the chemical lotions, he said.

Some parents do not want to use chemical treatments for their child and opt to use herbal products.

However, Dr Roberts warned that these were unregulated and were potentially harmful.

He agreed that new treatment options were needed.

He said a promising experimental treatment was silicone-based gels that encase the louse and stop it feeding so it dies.