The bacteria commonly responsible for
food poisoning belong to the groups
SALM ON ELLA, CAMPYLOBACTER,
E . COLL,
certain strains of which are able to mul-
tiply rapidly in the intestines to cause
widespread inflammation. Food poison-
ing may also be caused by
l l s t e r l a
is an uncommon,
life-threatening form of food poisoning
caused by a bacterial toxin.
The viruses that most commonly cause
food poisoning are astravirus, rotavirus,
and Norwalk virus (which affects shell-
fish). This can occur when raw or partly
cooked foods have been in contact with
water contaminated by human excrement.
Non-infective causes include poison-
ous mushrooms and toadstools (see
fresh fruit and veg-
etables contaminated with high doses
of insecticide, and chemical poisoning
from foods such as fruit juice stored in
containers made partly from zinc.
The onset of symptoms depends on the
cause of poisoning. Symptoms usually
develop within 30 minutes in cases of
chemical poisoning, between 1
hours in cases of bacterial toxins, and
between 12 and 48 hours with most
bacterial and viral infections. Symptoms
usually include nausea and vomiting,
diarrhoea, stomach pain, and, in severe
and collapse. Botulism af-
fects the nervous system, causing visual
disturbances, difficulty with speech, para-
lysis, and vomiting.
The diagnosis of bacterial food poi-
soning can usually be confirmed from
examination of a sample of faeces.
Chemical poisoning can often be diag-
nosed from a description of what the
person has eaten, and from analysis of
a sample of the suspect food.
Mild cases can be treated at home.
Lost fluids should be replaced by intake
of plenty of clear fluids (see
In severe cases, hospital treat-
ment may be necessary. Except for
botulism, and some cases of mushroom
poisoning, most food poisoning is not
serious, and recovery generally occurs
within 3 days. However, some strains of
can seriously damage red blood
cells and cause
The foot has 2 vital functions: to
support the weight of the body in
standing or walking and to act as a lever
to propel the body forwards.
The largest bone of the foot, the heel-
is jointed with the
ankle bone (the talus). In front of the
talus and calcaneus are the tarsal
bones, which are jointed the 5 meta-
tarsals. The phalanges are the bones of
the toes; the big toe has 2 phalanges;
all the other toes have 3.
BONES OF FOOT
Tendons passing around the ankle
connect the muscles that act on the
foot bones. The main blood vessels and
nerves pass in front of and behind the
inside of the ankle to supply the foot.
The undersurface of the normal foot
forms an arch supported by ligaments
and muscles. Fascia (fibrous tissue) and
fat form the sole of the foot, which is
covered by a layer of tough skin.
Injuries to the foot commonly result in
of the metatarsals and phal-
anges. Congenital foot abnormalities
are fairly common and include club-foot
common deformity in which a thickened
(fluid-filled pad) lies over the
joint at the base of the big toe.
are small areas of thickened skin and
are usually a result of tight-fitting
develop on the soles of the feet.
is a fungal infection that
mainly affects the skin in between the
often affects the joint at the
base of the big toe. An ingrowing toe-