enzyme. Drugs include lamivudine, zido-
vudine(AZT), efavirenz, and stavudine.
Reye’s syndromeA rare disorder in
which brain and liver damage follow a
viral infection. Children over 15 are rarely
affected. The cause is unknown, but aspi-
rin seems to be a predisposing factor to
developing the condition and is there-
fore not recommended for children.
The disorder starts as the child recov-
ers from the infection. Symptoms include
uncontrollable vomiting, lethargy, mem-
ory loss, and disorientation. Swelling of
the brain may cause seizures, distur-
bances in heart rhythm, coma, and
cessation of breathing.
Brain swelling may be controlled by
corticosteroid drugsand byintravenous
infusionsof mannitol. Dialysisor blood
transfusionsmay be needed. If breathing
stops, a ventilatoris used.
The death rate is around 10 per cent,
and higher for those who have seizures,
lapse into deep coma, and stop breath-
ing. Permanent brain damage may occur.
rhabdomyolysisDestruction of mus-
cle tissue accompanied by the release
of myoglobininto the blood. The com-
monest cause is a severe, crushing
muscle injury (see crush syndrome).
Other causes include polymyositisand,
rarely, excessive exercise. There is usually
temporary paralysisor weakness of the
affected muscle. Except in cases of
severe injury, the condition clears up
without treatment.
rhabdomyosarcomaA very rare can-
cerous muscle tumour. Treatment is by
surgical removal, radiotherapy, and anti-
cancer drugs.
rhesus immunoglobulinSee anti-
D(Rh 0 ) immunoglobulin.
rhesus incompatibilityA mismatch
between the blood group of a Rhesus
(Rh)-negative pregnant woman and that
of her baby. In certain circumstances,
this mismatch leads to haemolytic dis-
ease of the newborn.
The Rh system is based on the pres-
ence or absence in the blood of several
factors, the most important of which is
a substance called D antigen. Rh-positive
blood contains D antigen, whereas Rh-
negative blood does not. The blood
type is determined by genes.
Rhesus incompatibility results if a Rh-
negative woman is exposed to the
blood of her Rh-positive baby while it is
being born. There are usually no prob-
lems during the first pregnancy with a
Rh-positive baby. However, the woman
may produce antibodiesagainst the D
antigen; in a subsequent pregnancy
with a Rh-positive baby, these antibod-
ies may cross the placenta and attack
the red blood cells of the fetus. A Rh-
negative woman can also be sensitized
if she has had a miscarriage, abortion, or
amniocentesis, in which the fetus’s Rh-
positive blood enters her circulation.
Rhesus incompatibility is now uncom-
mon because injections of anti-D(Rh 0 )
immunoglobulinare given routinely to
Rh-negative women during pregnancy
and at delivery. They are also given after
miscarriage, abortion, amniocentesis, or
any procedure that might result in expo-
sure of the mother to fetal blood cells.
Rhesus isoimmunizationThe devel-
opment of antibodies against Rhesus
(Rh)-positive blood in a person who has
Rh-negative blood (see haemolytic disease
of the newborn; Rhesus incompatibility).
rheumatic feverA disease that causes
inflammation throughout the body, espe-
cially in the joints. Now rare in developed
countries, it is an important cause of
heart disease in developing countries. It
is most common in children aged 5–15.
Rheumatic fever is believed to be an
autoimmune disorderinduced by certain
strains of streptococcal bacteria, and
always follows a throat infection. It can
usually be prevented by antibiotic drugs.
The disease causes fever with pain,
inflammation, and swelling of the larger
joints. The heart valvesmay be scarred,
leading to mitral stenosisor mitral incom-
petence. Involvement of the nervous
system may cause Sydenham’s chorea.
The condition may be suspected when
arthritis moves from joint to joint but
may be discovered only after develop-
ment of heart failureor a heart murmur.
Treatment is with penicillin drugs,
aspirinor other salicylate drugs, and, in
some cases, corticosteroid drugs.
rheumatismA popular term for any
disorder that causes pain and stiffness
in musclesand joints.REYE’S SYNDROME RHEUMATISM
R