Bma Illustrated Medical Dictionary

The bacteria commonly responsible for

food poisoning belong to the groups

SALMONELLA, CAMPYLOBACTER, and E. COLI,

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 LISTERIA(see

listeriosis). Botulismis 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

mushroom poisoning), 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 and 12

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

cases, shockand 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 rehydration

therapy). 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

E. COLIcan seriously damage red blood

cells and cause kidney failure. (See also

cholera; dysentery; typhoid fever.)

footThe 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-

bone (see calcaneus), 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.

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

fractureof the metatarsals and phal-

anges. Congenital foot abnormalities

are fairly common and include club-foot

(see talipes), and claw-foot. A bunionis a

common deformity in which a thickened

bursa(fluid-filled pad) lies over the

joint at the base of the big toe. Corns

are small areas of thickened skin and

are usually a result of tight-fitting

shoes. Verrucas (see plantar warts)

develop on the soles of the feet. Ath-

lete’s footis a fungal infection that

mainly affects the skin in between the

toes. Goutoften affects the joint at the

base of the big toe. An ingrowing toe-

nail (see toenail, ingrowing) commonly

FOOT FOOT

F

Phalanges

FOOT

Tarsals

Metatarsals

Calcaneus

BONES OF FOOT