Preventive measures should be taken in
any area where mosquitoes are ram-
pant. The most effective measures are
wearing long sleeves and socks, placing
mosquito screens over windows, and
using insect-repellent sprays or slow-
burning coils that release insecticidal
smoke. Mosquito nets should be placed
over beds. (See also
insect bites; insects
A condition that some
people experience during road, sea,
or air travel. Symptoms range from un-
easiness and headache to distress,
excessive sweating and salivation, pal-
lor, nausea, and vomiting.
Motion sickness is caused by the effect
of repetitive movement on the organ of
balance in the inner ear. Factors such as
anxiety, a fume-laden atmosphere, or
the sight of food may make the condi-
tion worse. So, too, can focusing on
nearby objects; sufferers should look at
a point on the horizon.
Motion sickness may be prevented or
acupressure bands worn on the wrist.
A term used to describe anything
that brings about movement, such as a
motor neuron disease
A group of dis-
orders in which there is degeneration
central nervous sys-
that control muscular activity. This
causes weakness and wasting of the
muscles. The cause is unknown.
The most common type of motor neu-
sclerosis (ALS or Lou Gehrig's disease).
It usually affects people over the age of
50 and is more common in men. Some
cases run in families. Usually, symp-
toms start with weakness in the hands
and arms or legs, and muscle wasting.
There may be irregular muscle contrac-
tions, and muscle cramps or stiffness.
All four extremities are soon affected.
Progressive muscular atrophy and pro-
gressive bulbar palsy both start with
patterns of muscle weakness different
from ALS but usually develop into ALS.
There are 2 types of motor neuron dis-
ease that first appear in childhood or
adolescence. In most cases, these con-
ditions are inherited.
affects infants at birth or soon
afterwards. In almost all cases, progres-
sive muscle weakness leads to death
within several years.
muscular atrophy begins in childhood or
adolescence, causing progressive weak-
ness but not always serious disability.
There are no specific tests for motor
neuron disease. Diagnosis is based on
careful clinical examination by a neurol-
ogist. Tests including
may be performed.
The disease typically goes on to affect
the muscles involved in breathing and
swallowing, leading to death within 2-4
years. However, about 10 per cent of
sufferers survive for
Nerve degeneration cannot be slowed
and the use of
various aids may help to reduce dis-
ability. The drug riluzole is used to
extend life (or the time until mechanical
Any of a large group of
exist as many-celled, filamentous col-
onies. Some moulds are the source of
Others can cause dis-
eases such as
An illness that can
affect people who have ascended rapidly
to heights above 2,400m-3,000m. Moun-
tain sickness is caused by the reduced
atmospheric pressure and oxygen levels
that occur at high altitude.
The oral cavity, which breaks
food down for swallowing (see
) and is used in breathing. In
addition, it helps to convert sound
vibrations from the
tumour that affect the lips, tongue, and
oral cavity. Lip cancer and tongue can-
cer are the most common types.
Predisposing causes of mouth cancer
, drinking alcoholic
spirits, tobacco-smoking, chewing tob-
acco, and inhaling snuff. Irritation from
ill-fitting dentures or jagged teeth are
other factors. Men are affected twice as
often as women; most cases occur in
men over the age of 40.
Mouth cancer usually begins with
a whitish patch, called
small lump. These may cause a burning