treating the disorder. In severe cases,
intravenous infusion of nutrients is
needed (see feeding, artificial).
maladjustmentFailure to adapt to a
change in one’s environment, resulting
in inability to cope with work or social
activities. Maladjustment can occur as a
reaction to stressful situations, such as
divorce or moving house. There may be
feelings of depressionor anxiety, or
behavioural problems in childrenand in
adolescents. Maladjustment usually dis-
appears when a person is removed from
the stressful situation or adapts to it.
malaiseA vague feeling of being unwell.
malalignmentPositioning of teethin
the jawso that they do not form a
smooth arch shape when viewed from
above or below (see malocclusion).
Malalignment may also refer to a
fracturein which the bone ends are
not in a straight line.
malar flushA high colour over the
cheekbones, with a bluish tinge caused
by reduced oxygen concentration in the
blood. Malar flush is considered to be a
sign of mitral stenosis, which often fol-
lows rheumatic fever. However, malar
flush is not always present in mitral
stenosis, and many people with this
colouring do not have heart disease.
malariaA serious disease caused by
parasitic protozoa called plasmodia.
The infection is spread by the bite of
anopheles mosquitoes and is prevalent
throughout the tropics. Malaria causes
severe fever, and, in some cases, fatal
complications affecting the kidneys,
liver, brain, and blood.
There are 4 species of plasmodia that
cause malaria: PLASMODIUMFALCIPARUM,
PLASMODIUMVIVAX, PLASMODIUMOVALE,
and PLASMODIUM MALARIAE. When a
mosquito carrying any of these species
bites a human, the plasmodia enter the
bloodstream. They invade the liver and
red blood cells, where they multiply.
The red cells then rupture, releasing the
new parasites. Some of them infect new
red cells, and the others develop into
forms that can infect more mosquitoes.
Falciparum malaria infects more red
cells than the other species and there-
fore causes a more serious infection.
Most cases of this form occur in Africa.
Symptoms of malaria include fever,
shaking, and chills. There may also be
severe headache, general malaise, and
vomiting. The fever often develops in
cycles, occurring every other day (in
vivax and ovale infections) or every 3rd
day (in malariae infections).
Falciparum malaria can be fatal within
days. Infected red cells become sticky
and block blood vessels in vital organs.
The spleenbecomes enlarged and the
brainmay be affected, leading to coma
and convulsions. Destruction of blood
cells causes haemolytic anaemia (see
anaemia, haemolytic). Kidney failure and
jaundice often occur.
A diagnosis is made by examining a
blood sample under a microscope to
view the parasites. Chloroquineis the
usual treatment for species other than
falciparum. Falciparum malaria is treat-
ed with quinine, mefloquine, or with
proguaniland atovaquone. People with
vivax or ovale malaria must also take
the drug primaquine. In severe cases,
blood transfusions may be needed.
Preventive antimalarial drugs should
be taken by all visitors to malarial coun-
tries. Doctors should be consulted for
up-to-date advice on the choice and
dosages of drugs to be taken.
malathionAn antiparasitic drug, which
is used to treat skin or hair infestations
such as liceand scabies.
malformationA deformity, particularly
one resulting from faulty development.
malignantA condition that tends to be-
come progressively worse and to result
in death. The term is primarily used to
refer to a cancerous tumourthat spreads
from its original location to form second-
ary tumours in other parts of the body.
malignant melanomaSee melanoma,
malignant.
malingeringThe deliberate simulation
of symptoms for a purpose, such as
taking time off work or obtaining com-
pensation. Malingering is different from
factitious disordersand hypochondriasis,
in which symptoms are not under the
individual’s voluntary control.
mallet fingerInjury to the tendon or
bone in a fingertip that forces the tip into
a bent position. A common sports injury,
it occurs when a ball strikes a finger.MALADJUSTMENT MALLET FINGER
M