Aren't they cute, trundling off to school with their little books, pencil boxes, lunch boxes and caps? They make friends, trade sandwiches, pencils, books . . . and caps.

And then they come home, with the wages of childhood friendship nestled against their little scalps.

Nits.

Nits, the eggs of head lice, have very little to do with cleanliness or suburbs versus city, or good habits, or economic background. Nits are often spread through the sharing of caps and combs, or by children tumbling around together in roughneck play.

Because the head louse prefers to lay its eggs in straight hair, it was thought this made them less troublesome to blacks. This has become less true in recent years, possibly, some speculate, because of natural hair styles.

The head louse and its nits have been epidemic in the past few years -- maybe 10 million infested heads a year -- and show no signs of slowing down.

It is certainly an unpleasant phenomenon -- and once entrenched in a family sometimes hard to eradicate -- but it is something less than the noisome and disease-carrying body louse, which is linked clearly to unclean, unsanitary conditions.

Nor does the head louse require that the head of its innocent host be shaved nor even shorn. Especially, parents should not rush to pour on prescription insecticides at the first sign of the telltale nit. Most of these preparations contain lindane, a DDT relative and are considered potentially dangerous not only to the lice, but to the host.

Non-prescription preparations containing pyrethrins are considered safer -- pyrethrins are made from chrysanthemums -- but still may cause occasional allergic reactions, and usually require more effort to assure their effectiveness.

Fine-tooth combs to take out the nits -- usually laid close to the scalp -- plus daily changing of bed linens and personal clothing, their laundering in very hot water (at least 130 degrees) and constant vigilance should prevent recurrence. A new, patented comb (with a small magnifying glass in the handle) was reportedly highly successful in a Greenwich, Conn., school trial and should be on the market this fall.

For more information on the comb, a free booklet on Treating Lice Infestation or a poster called the ABC's of Lice, write Pfizer, Inc. (manufacturers of one of the pyrethrin-based products, RID) 235 East 42nd St. N.Y., N.Y. 10017.

Flu view: Last year turned out to be a relatively mild flu season in most of the U.S., but it's probably too much to hope for another.

Flu shots are important for especially vulnerable populations--old people, young children and the chronically ill -- but there are some new weapons in the anti-flu arsenal.

New tests of the anti-viral agents amantadine and rimantadine seem to confirm earlier studies indicating their effectiveness against the flu bugs. Amantadine is FDA-approved and marketed in this country as Symmetrel. Rimantadine has not yet been approved for use in this country, but in a study published recently in the New England Journal of Medicine, it appeared to have fewer side effects (like jitteriness or insomnia) than amantadine.

Some experts have expressed concern that these anti-flu pills might be so over-prescribed that the adaptable flu bugs would quickly build up resistant strains, but NEJR editorial writer Dr. R. Gordon Douglas Jr., suggests that "in an epidemic of influenza, amantadine would be indicated for many persons," including those for whom vaccines may not be enough protection or those in institutions, for example, during an outbreak.

E experiments: For some time, health-food buffs have been promoting Vitamin E (mainly a substance called alpha tocopherol) as a cure for the painful breast cysts many women develop, usually before their menstrual periods. The ailment is known as fibrocystic breast disease or cystic mastitis.

Dr. Robert London, director of clinical research in the department of Obstetrics and Gynecology at Sinai Hospital in Baltimore, has been studying the potential benefits of Vitamin E for this possibly pre-cancerous condition. He has found that Vitamin E does affect the blood level of certain hormones and may alter levels of lipids. Early results strongly suggest a beneficial effect on some patients with the disease.

Sinai Hospital and Dr. London are seeking volunteers to continue their study. They should be healthy women over 18 with regular menstrual cycles, not taking hormones. They must be willing to be examined twice during a three-month period. Free breast examinations, laboratory tests and therapy will be provided.

London emphasizes that no woman with lumps in her breasts should try to treat herself with Vitamin E (or anything else) but should be under a physician's care.

Other approaches to the problem have involved drug therapy and a diet free of caffeine and other members of the class of chemicals called methylxanthines. Dr. John Peter Minton of Ohio State University has found that the ubiquitous chemicals interfere with the cell's ability to turn off the functions that produce the cysts. Diets free of coffee, tea, chocolate, cola and other caffeine-containing products appear to lessen or eliminate the disease, according to his studies. However, subsequent studies have not borne up his initial findings.

"It would be nice if something as benign as a vitamin could be shown to be useful," says London, who emphasizes that his work is still preliminary.

Volunteers should call 301-578-5535 (in Baltimore) for information.