Lice
Lice are barely visible
blood-sucking parasites that live on hairy parts of the human body.
Lice
seldom cause serious medical problems, but are very contagious and can be
annoying.
Intense scratching can break the skin
and lead to bacterial infections.
There are three types of lice: head
lice, body lice and pubic lice. Treatment depends on the area infected.
Contrary to popular belief, head lice
are not related to poor hygiene.
Treatment must kill the adult lice and eggs (nits) on the body, bedding and
clothing to be effective
Description
Lice are barely visible, wingless insects between 1 and 3 mm in size
that live on human beings and feed on blood. These parasites seldom cause
serious medical problems, but are annoying and very contagious, spreading easily
from person to person by body contact and shared clothing and other personal
items. Every four hours or so, a louse bites into a tiny blood vessel for a
meal. Because it injects an anaesthetic, you won’t feel the initial bite.
However, as its saliva gets under your skin, bites begin to itch. Intense
scratching often breaks the skin, and can lead to bacterial infections.
There
are three types of lice: head lice, body lice and pubic lice.
Head lice
Head
lice (Pediculus humanus capitis) are about the size of a sesame seed, and
can easily be seen, although they hide quickly when exposed to light. Their
eggs, called nits, are barely visible whitish ovals cemented to hair shafts.
Head
lice are spread by personal contact and by shared brushes, combs, hats and other
personal items. The infestation sometimes extends into the eyebrows, eyelashes,
and beard. Head lice are a common scourge of school children of all social
strata.
Body lice
Body
lice (Pediculus humanus corporis) look very much like those found on the
head, but are actually a different species. While they aren’t as easily
transmitted as head lice are, they are more difficult to spot, hiding in the
seams of clothing and folds of bedding when not actually feeding.
Body
lice infestation is usually found in people who have poor hygiene and those
living in close quarters or crowded institutions. These lice can carry diseases
such as typhus, trench fever and relapsing fever.
Pubic lice
Pubic lice (Phthirius pubis) are yellow-grey insects found in
the pubic region, and are typically spread during sexual contact. The size of a
pinhead, they are slightly translucent and barely visible against light-coloured
skin. With their shorter, rounder body shape and crab-like claws with which they
cling to hair, they resemble crabs – hence their popular name. The eggs, which
are barely visible, are tiny white particles glued so firmly to hair shafts that
they cannot be removed by normal washing.
Cause
Contrary to popular belief, contracting lice is not related to poor
hygiene – in fact, head lice are thought to prefer clean hair to dirty hair.
However, good hygiene can combat body lice.
Symptoms
Head
lice: intense itching on the scalp, especially behind the ears and at the nape
of the neck. Children may hardly notice head lice or may have only a vague scalp
irritation in the beginning. With advanced infestation, the scalp may become red
and inflamed, with swollen glands near the area where the lice are living.
Body
lice: itching is generally most intense on the shoulders, buttocks and abdomen.
Signs of lice include unexplained scratch marks on the body, hives, eczema, or
small red pimples on the shoulders or torso. If the lice are not treated, welts
may develop.
Pubic
lice: Pubic lice causes continual itching around the penis, vagina and anus, and
perhaps a rash.
Prevalence
Lice live successfully all over the world, wherever people gather in
close proximity, for example in schools.
Course
Once you have been infected with adult lice, they will attach their
eggs (nits) to hair shafts on various parts of the body. The nits hatch in eight
to ten days, producing more lice. Lice can live up to a week on items such as
bedding, sleeping bags, clothing and towels.
When to
see a doctor
Call your doctor if you need help getting rid of lice, or if
scratching has led to an infection.
Diagnosis
Head
lice: itching and scratching is the hallmark of this condition. Your doctor will
examine the scalp for tiny grey insects, usually at the nape of the neck or back
of the head where there is the most hair. The doctor will also look for shiny,
small, greyish-white oval-shaped eggs (nits) firmly stuck close to the base of
hair shafts. They look like flakes of dandruff that cannot be brushed off.
Body
lice: Because body lice are difficult to spot, intense itching on the shoulders,
buttocks and abdomen, together with unexplained scratch marks on the body,
hives, eczema, and small red pimples on the shoulders or torso are taken as
signs of their presence.
Pubic lice: Pubic lice are
particularly difficult to find and may appear as tiny bluish spots on the skin.
However, they do leave a scattering of miniscule, dark-brown specks (louse
excrement) on underwear where it comes into contact with the genitals and anus,
and these can form the basis of a diagnosis.
Treatment
The goal of treatment is to remove all lice and nits. This usually
requires repeated efforts, because a few adult lice may escape by hiding in
clothing or bedding, and eggs are difficult to kill.
Head lice
The most common treatment for head lice is to kill the adults with an
insecticidal shampoo and to clear out the nits with a special fine-toothed comb.
Of the medications for lice, permethrin is the safest, most effective, and most
pleasant to use, and is available over the counter. For best results, follow the
directions exactly. Other family members should be treated too – about 60% of
infected children have relatives who carry lice.
To
eliminate all lice and successfully prevent reinfection, wash all clothing,
towels and bed linen in hot, soapy water, and dry them in a hot dryer. You can
also disinfect bedding and other items such as hats and clothing by placing them
in a sealed plastic bag for 14 days; the nits will hatch in about a week and die
of starvation. Brushes and combs can be disinfected by soaking them in hot,
soapy water for 10 minutes.
If you
prefer to avoid the use of insecticides, try a "combing only" technique. Wash
the hair with an ordinary shampoo and conditioner and leave wet. With a
fine-toothed comb, stroke slowly outward from the roots through one lock of hair
at a time. Lice will land on the back of the comb, get caught between the teeth,
or fall off. Space at least 30 strokes over the head. Repeat every three days.
Because new-born lice do not lay eggs for the first week, all lice should
disappear after about two weeks of combing.
Body lice
To treat body lice, wash the entire body with soap and water. If this
is not effective, you may have to use an insecticidal preparation, which usually
kills all the lice. Wash all clothing and bedding in hot water and dry them in a
hot dryer. Store clothes for two weeks in sealed plastic bags or place them in
dry heat of 60 °C for three to five days.
Pubic lice
Pubic lice can be treated with non-prescription medications
containing pyrethrins (natural insecticides). Sexual partners will also have to
be treated. "Crabs" are sometimes found on eyelashes and eyebrows, where they
are difficult to treat. Remove them with tweezers, or use an ophthalmic ointment
such as physostigmine. Ordinary petroleum jelly may kill or weaken lice on
eyelashes too.
Prevention
Prevention of head lice is difficult, especially among children,
since lice spread quickly from head to head. To help prevent lice, prevent
children from sharing hats, hooded coats, scarves, combs, brushes, pillows, and
soft toys. If you discover lice on your child, notify school or day-care
authorities immediately, since classmates are likely to be infected. Infected
children should be kept home from school until they are treated.
The best
way to prevent lice in the genital area is monogamy or avoidance of intimate
sexual contact. Condoms are not a good protection against lice because they do
not cover the hairy areas where the lice live. You should also avoid contact
with contaminated clothing, bed linen and toilet seats.
