by Dr. Andrew Reekie, 15 Oct 98
Shock, horror - there are lice about
again. The abhorrent reaction of the middle class Mum to lice is only exceeded
by their response to roundworms emerging from you know where. . . . Actually
most of you are perfectly sensible about lice: they are probably currently
on the increase, perhaps due to increasing resistance to insecticide and
are certainly no respecters of diplomatic status or social position.
Can I make the following points, most
of which are obvious:
A brief account of the natural history
must be added. The lice live in the nice warm environment of the scalp,
feeding on blood. They lay their eggs at the base of the hairs and you
can get some idea of the period of infection by the distance of the eggs
from the scalp: hair grows at approximately 1 cm/week. Eggs hatch after
7 - 10 days and take a further 10 days to become fully developed adults,
after three larval stages. Hence the egg to egg time is 17 - 20 days. This
is why mechanical methods are only effective if maintained for at least
Lice do not jump. They are spread
to head, or rather hair to hair, contact. Girls tend to go into a huddle
more often than boys and may have longer and more straggly hair. Hence
they have a considerably higher incidence than boys. Changing hair style
is well worth considering although it is not absolutely necessary to shave
the head Bangladeshi style!
None of the modern insecticides (Malathion,
Carbaryl and Permethin) are any longer totally reliable. Resistance exists
to all of them. The shampoo preparations may kill the adult lice but are
much less effective against the eggs. Alcoholic solutions with which all
the hair must be thoroughly wetted are much better although less pleasant.
They must be used cautiously in asthmatics and avoided in babies under
six months. Moreover there is some evidence that they are inactivated by
the chlorine in swimming pools and I suggest children are stopped from
swimming for two days after application.
All these insecticides are slightly toxic.
You should not therefore use them without evidence of active infection
which involves combing. Although a second application one week after the
first improves the efficiency, more tli an two applications must be avoided.
Mechanical methods of removing lice are
worth using but are labour intensive and require a heavy commitment by
parents. They are probably best used in conjunction with one application
of insecticide at the end. They are also appropriate when insecticides
have been shown to have failed or in families where organic techniques
are favoured!! You need a special louse comb with very fine teeth. The
hair is saturated with conditioner and combing is carried out until there
are no more lice found, every fourth day for a minimum of six times - this
means about half an hours combing. For every session in which an adult
louse is found, the treatment period must be extended by another four days.
Finally, those of you with school age
children should be vigilant and, ideally, examine your children's scalps
with a fine tooth comb about every week. In this way you will pick up the