Book of Medical Disorders in Pregnancy - Tintash

organization, 1,612 million people live
in 107 countries where malaria is
endemic. More than 1.25 million people
died of malaria in 1977. The disease is
usually acquired by the bite of an
infected female anopheles mosquito, but
it can be transmitted by infected blood
trans-fusion. Sporozoite released in the
blood stream enters the liver cells
(exoerythrocytic stage) and divide. The
sporozoite matures into merozoite inside
the liver cells. The liver cell ruptures and
the merozoite are released they invade
red blood cells (erythrocytic stage). The
intra erythrocytic parasite divides again
and the infected red blood cell ruptures.
The cycle is repeated again by invasion
of other red blood cells. This process
takes 72 hours for P. malariae and 48
hours for the other species. Some
merozoite develops into male and female
gametocytes and initiates the sexual
cycle of reproduction.
Gametocytes usually appear in the blood
of the infected host in about two weeks
after the onset of symptoms. If they are
ingested by a female anopheles mosquito
during the bite~ the male and female
gametocytes unite in the stomach of the
mosquito. The sporozoite takes 1 to 5
weeks to develop, depending on their
species. Sporozoites become concentrated
in the salivary glands of the
mosquito and are injected into man
during the bite.
When sporozoite of P. vivax or P. ovale
which have persisted in the liver mature
into merozoite and are released into the
bloodstream> relapse of symptoms occurs.
PJalciparum and P. malariae do not
persist in the liver, but can remain
dormant within the erythrocyte and the
infection may reoccur after many
months or years.
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Pathology - The disease is caused by
four different species of plasmodium.
The plasmodium vivax, and plasmodium
malariae, is transmitted to man by anopheles
mosquitoes. It is occasionally
seen in patients who have received a
blood transfusion from an infected donor
and in heroin addicts. Infrequently, it can
be transmitted by mother to the fetus in
utero. The pathological lesions which
occur can be due to changes caused by
the parasite i.e. the reaction which the
host produces in response to the
presence of parasite and the effect of the
infection on the individual organs.
The pathophysiology of malaria is basically
the result of local disturbances of
the microcirculation, particularly in the
brain, liver, lungs and kidneys.
A major factor in malaria pathogenesis is
the disturbance this infection causes to
tissue oxygenation. Local tissue anoxia
occurs due to stasis and is aggravated by
anemia produced by hemolysis. Sometimes
anoxia is so severe that complete
circulation is block· ed. Disseminated intravascular
coagulopathy can be initiated
and tissues may be severely damaged.
When the host is non immune, death
from malaria is often seen in P.
falciparum infection. Shock secondary to
hypovolemia, adrenal insufficiency,
renal failure, hepatic insufficiency,
pulmonary edema, or cerebral ischemia
is usually the cause of death. In P. vivax
infection, death is occasionally caused
by splenic rupture. Nephrotic syndrome
can occur as a result of longstanding P.
malariae infection, but this is not very
common.
Clinical features - An infected
mosquito bites a susceptible woman and
infests her with plasmodia in the