T
TOURETTE'S SYNDROME
TOXOPLASMOSIS
TOUCH
TOUCH RECEPTORS IN SKIN
cornea is several hundred times more
sensitive to painful stimuli than the
soles of the feet. (See also
sensation.)
Tourette's syndrome See
Giles de la
Tourette's syndrome.
tourniquet A device placed around a
limb to compress blood vessels. A tour-
niquet may be used to help locate a
vein for an intravenous injection or for
the withdrawal of blood. An inflatable
tourniquet, called an
Esmarch's bandage
,
is used to control blood flow in some
limb operations. The use of a tourniquet
as a first-aid measure to stop severe
bleeding can cause
gangrene.
toxaemia Presence in the bloodstream
of
toxins
produced by
bacteria.
(See also
preeclampsia; toxic shock syndrome.)
toxaemia
of
pregnancy See
pre-
eclampsia.
toxicity The property of being toxic (pois-
onous). Toxicity also refers to the severity
of adverse effects or illness produced by
a
toxin
, a
poison
, or a drug overdose.
toxicology The study of
poisons
. (See
also
poisoning.)
toxic shock syndrome An uncommon,
severe illness caused by a
toxin
pro-
duced by the bacterium
staphylococcus
aureus.
Many cases occur in women
using vaginal tampons. Other cases have
been linked to use of a contraceptive
cap, diaphragm, or sponge (see
contra-
ception),
or to skin wounds or infections
by the bacterium elsewhere in the body.
A high fever, vomiting, diarrhoea, head-
ache, muscle aches and pains, dizziness,
and disorientation develop suddenly. A
widespread skin rash that resembles sun-
burn and also affects the palms and
soles, develops. Blood pressure may fall
dangerously low, and
shock
may develop.
Other complications include
kidney fail-
ure
and
liver failure
. Treatment in an
intensive care unit may be needed.
toxin A poisonous protein produced by
pathogenic (disease-causing) bacteria,
various animals, or some plants. Bacte-
rial toxins are sometimes subdivided into
3
categories:
endotoxins,
which
are
released from dead bacteria;
exotoxins
,
which are released from live bacteria; and
enterotoxins
, which inflame the intestine.
(See also
poison; poisoning; toxaemia.)
toxocariasis An infestation of humans,
usually children, with the larvae of
toxo-
cara canis:
a small, threadlike worm
that lives in the intestines of dogs.
Children who play with an infested dog
or soil contaminated with dog faeces,
and who then put their fingers in their
mouths, may swallow some of the worm
eggs. The eggs hatch in the intestines,
and the released larvae migrate to organs
such as the liver, lungs, brain, and eyes.
Usually, infestation causes mild fever
and
malaise
, which soon clears up; but
heavy infestation may lead to
pneumonia
and
seizures
. Loss of vision may occur if
larvae enter the eye and die there.
A diagnosis is made from sputum
analysis, and by a
liver biopsy
. Severe
cases require treatment in hospital with
tiabendazole
and an
anticonvulsant drug.
toxoid An inactivated bacterial
toxin.
Cer-
tain toxoids are used to immunize against
specific diseases, such as
tetanus.
toxoplasmosis An infection caused by
the
protozoan toxop^ sma gondii
that is
often caused by eating undercooked
meat from infected animals, or by hand-
ling faeces from infected cats. In most
cases there are no symptoms, but some-
times there may be a feverish illness
that resembles infectious
mononucleosis
.
Retinitis (inflammation of the retina)
and
choroiditis
may also develop. In peo-
ple with an
immunodeficiency disorder
toxoplasmosis may cause lung and heart
damage and severe
encephalitis
.
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