My children go to a really lousy school. In fact all the schools they’ve gone to have been lousy. And I don’t mean educationally. By lousy I mean exactly that: louse infested. The head louse, Pediculus humanus capitas, is making a comeback. Big time. And this is in spite of improvements in public health and personal hygiene, not to mention insecticides. Head lice have evolved themselves right out of these tight spots. Now in Europe and America, except for the common cold, head lice infestation occurs more often than all the other childhood diseases combined.

The Scottish Centre for Infection and Environmental Health in Glasgow has no statistics on lice infestation because it is not a notifiable disease. But the information the consultant did offer was the same I had been hearing from teachers and nurses in both the state and independent sector. Lice infestation is becoming more frequent and more intractable.

The Health Education Board for Scotland is unequivocal on the matter:

“Every child will encounter the problem at some point in their school career.” Down south, two out of three children are estimated to have headlice during the academic year and ministers are considering the reintroduction of nit nurses.

Head lice outbreaks mostly occur in primary schools. Teenagers and adults are believed to wash their hair too frequently and put too much gunk on it to give lice a chance. And younger children, in their daily rough and tumble, are in closer physical contact and reinfect each other.

After years of smug little asides to my husband about how our children never got lice, one of them did. The scratching of the head and neck were a dead give away. When I first combed our son’s short hair over some white paper all the stages of the life cycle fell out: big mothers, fathers, brothers, sisters and nits. It was disgusting. Just remembering it makes my skin crawl.

The lice swiftly spread. Shocked, dismayed, and absolutely mortified, I got as much information as I could from books, the Internet, the labels of various over the counter lotions, and the Bug Busting Kit my children’s school bought in to deal with yet another outbreak. I instinctively disliked the sound of the fast acting chemical treatments. Besides, the horrible hard little nits or eggs are impervious to them.

So I went for the Bug Buster regime put together by the health charity Community Hygiene Concern. It’s an ideal opportunity for more co-operation between teachers and school health service staff. HEBS has actively encouraged such co-operation ever since a study in Fife showed it was woefully inadequate.

The Lothian Health Board regularly holds “Headlice Awareness Weeks” for primary schools. The next one is at the end of this month. Isn’t this yet another imposition on class time? Wrong! Dealing with lice can be worked into the 5-14 curriculum. No problem. Take environmental studies. There you find the topics “understanding living things and the processes of life” and “the interaction of living things with their environment.”

Children think parasites are great. Get them to do a project. How about Lice and Soldiers? Tell them that in the Second World War one American GI was given a once-over by the health officials and they stopped counting after the 16,000th louse. He lived.

The Bug Busting method eschews the use of pesticides and instead favours a completely mechanical, whole-school approach. A nit comb and ordinary shampoo and conditioner are all you need. And time. The itching and scratching may clear up in a matter of days. But you may have missed some of the nits. Continue the protocol for two weeks so you can zap them too. (See the box on the next page.) If you think parents haven’t got time for the two week routine, read on. Learn about the quick cure insecticide lotions they can buy over the counter - the ones that parents might soak their child’s head in.

These chemicals are called synthetic pyrethroids - SPs for short. They act as nerve toxins. SPs were modelled after pyrethrum compounds, the natural and extremely powerful insecticides found in certain chrysanthemum plants. Over 2,000 years ago the Chinese used these dried flowers to rid themselves of lice and fleas. Pyrethrum and the synthetic pyrethroids work as nerve toxins on insect pests - and on us. But because we metabolise them swiftly and get rid of them, they are considered of low toxicity to humans.

SPs go by the names of permethrin, resmethrin, allethrin, tetramethrin, cyfluthrin, fluvalinate, fenvalerate, cypermethrin and phenothrin. You will find the SP phenothrin at the concentration of 0.20 per cent in the over the counter lice lotion Full Marks. I nearly put that on my children’s heads. For two hours. That’s what the instructions said.

Intrigued, I checked the can of fly spray I keep under the kitchen sink. It contains less of the SP allethrin (0.18 per cent) than Full Marks. My fly spray has Control of Substances Hazardous to Health (COSHH) regulations printed on it, and cautionary statements like: “Keep off skin. Wash hands and exposed skin after use. Keep in a safe place away from children.”

Would you spray insecticide on your child’s head and leave it for two hours? Then why soak your child’s hair in an even stronger concentration of insecticide?

Confused? So was the Massachusetts Department of Public Health web page fact sheet. It warned that precautions were necessary in the use of mosquito repellents that contain SPs. Yet its web page on the treatment of lice says to wash using the SP lotions and shampoos available over the counter.

The various SPs are strong stuff. If they’re not supposed to be toxic to humans, then why all the warnings on the insecticide spray cans? SPs can cause many health reactions, including allergic reactions and respiratory reactions - especially in asthmatics. And their use as pesticides is universal.

It gets more confusing. Piperonyl butoxide or PBO is an extra toxin added to make the SPs less quickly metabolised and therefore more effective in killing insects. PBO is in some lice treatment lotions and you will almost certainly see it as an ingredient of your pet flea killer.

As if all this wasn’t bad enough, only now are studies beginning to show what school health officials and parents have known for a long time. These chemicals do not seem to be as effective as they used to be.

Lice have been exposed to SPs, particularly permethrin, for years. Have we inadvertently selected for the strongest, most resistant lice? That has yet to be proved, but it is the only satisfactory explanation for persistent small outbreaks of lice. In Scotland local health authorities advocate the use of only one lice treatment lotion at a time. They rotate the recommendation from year to year to help reduce the build up of insecticide resistance in the louse population.

May I suggest a less toxic treatment? Just run a hot bath. Have a soak and shampoo to kill all the hatched lice, then follow the instructions in the box on the next page to get rid of the nits.

Let’s not expose our children, ourselves or our environment to potentially hazardous pesticides that seem to be losing their punch anyway. We need to do what all the experts recommend: nit pick.

Pamela Maitland teaches biology at George Watson’s College, Edinburgh. Her e-mail address is p.maitland @watsons.edin.sch.uk

FOR FURTHER INFORMATION

Contact the Bug Buster Hotline on 0181 341 7167 or at www.chc.orgbugbusting. Other useful organisations are:

* National Pediculosis Association at www.headlice.org

* Scottish Centre for Infection and Environmental Health on 0141 300 1100

* Health Education Board for Scotland on 0131 536 5500 or at www.hebs.scot.nhs.uk

* Lothian Health Board on 0131 536 9194

SHAMPOO

Lice can’t swim. In fact they drown. That’s why shampooing will keep them under control. With the lice all washed away, no more nits will be laid.

Shampoo everybody’s hair every day for two weeks. Everybody in your household, young and old. A parasitologist on a committee set up by the health department of Queensland, Australia, to combat local lice epidemics found that on a number of occasions asymptomatic grannies were the chronic reservoir of infection for household children.

After each shampoo, deal with everyone’s nits. They are the key to louse control. The nits are different from the lice because they do not die in the water. Nor do they float away.

Nits look like miniature wax tear drops attached firmly to the base of the hair shaft, and have to be removed with a nit comb.

Put on gobs of conditioner. Brush or comb the hair as usual, then go through the hair, section by section, with a fine toothed metal nit comb. You can get one from the chemist for less than pound;4.

The plastic nit combs in the Bug Busting Kit are not as effective. When they were handed out at our children’s school, they ended up as bookmarks.

Use more gobs of conditioner if the hair is long. My little girl has waist long hair, and I was using half a bottle every night.

It’s worth it. The nit comb becomes easier to use, and it’s harder for the nits to hang on when the hair shafts are like greased poles.

You can do all of this in or out of the bath. It is a very satisfying experience to collect the nits and lice in a plastic cup full of water. Do this by dipping the comb in the cup after every stroke through the hair.

It can also be gratifying to examine the bottom of the bath after the water has slowly drained away. Count the enemy dead.

A LOUSY LIFE

Throughout the life cycle from nit to nymph to adult, lice are completely dependent on the ecosystem of our scalps. The warmth, the humidity and the blood they drink are necessary to the lice. The hair shafts are essential, because it is there the female lice attach their nits. No hair, no nits.

Until the Second World War, shaving heads was the standard way to deal with Pediculus humanus capitas. Adult head lice look like sesame seeds with legs. Each of the six legs has claws which help them cling to the hair. The male adult louse is 1.0-1.5mm long. The female is bigger, about 1.8-2.0mm. For such small, soft creatures, they can move surprisingly quickly through the hair.

A louse appears to have a red body right after a blood meal. Later, when the blood has been digested, the body looks dark brown or black.

The female lays anything from 50 to 150 nits in her lifetime of up to one month. She attaches them at an angle with a glue like substance, one per hair shaft, right next to the scalp. Chances are you will find a group of nits about 0.5 cm along hair shafts - this is because the hair has grown.

The nits hatch after about eight or 10 days into tiny nymphs very similar to adult lice. Young nymphs are able to feed immediately, twice a day. Like the adults, one set of mouthparts attaches to the skin while other mouthparts pierce and suck.

A nymph has to shed its skin three times to reach adulthood in about 10 days. The nymphs and adult lice can only live between 20 and 48 hours without a blood meal - and only for a few hours if separated from the warm, humid conditions of their host.

Nobody knows exactly how lice spread. It is presumed that the lice crawl from person to person when there is close contact, and the nits are transferred when we share brushes, combs and hats.