•The infected female anopheline mosquito injects sporozoits that go to
The Disease Malaria
•There are four plasmodium’s that are specific for humans: P.
falciparum, P. vivax, P. ovale, and p. malariae. They are transmitted
through the bite of an infected anopheline mosquito, which injects
sporozoits from her salivary glands when feeding.
•The number of sporozoits inoculated is usually less than 25.
•The sporozoits travel via the bloodstream to the liver cells.
•The entire process takes less than 1 hour.
•The parasite multiples asexually to produce 10000 or more infective
•They then invade erythrocytes.
•They reproduce asexually producing merozoites, which are the
pathogenesis of the disease.
•Merozoites released from the erythrocytes invade other red cells and
continue the cycle of 10-fold parasite multiplication with extensive red
blood cell destruction.
•Some of the merozoits do not divide; instead they differentiate into
male or female gametocytes.
•When injected by a female mosquito, the male gametocyte divides into
eight-flagellated microgamete’s which escape from the red cells this
process is called exflagellation. They swim to the macrogamete and
one fertilizes it.
•The motile zygote, called the ookinete moves either between or through
the cells of the stomach wall
•The encysted zygote on the outside of the mosquito’s stomach is an
oocyst and multiplies and produces threadlike sporozoits
•The oocyst bursts releasing its sporozoits into the body cavity.
•The sporozoits find their way to the salivary glands.
•When the female feeds again, the transmission cycle has been
•In P. vivax, P. ovale and P. falciparum the period between fever bursts
is 48 hours, and for P. malariae it is 72 hours.
•The fever may reach up to 41 degrees and corresponds to the rupture of
the red cell as merozoites are released from the infected red cell.
•During the first few weeks of infection the spleen is palpable because it
is swollen from the accumulation of the parasitized red cells and the
proliferation of white cells.