Plasmodium vivax causes
benign or vivax malaria. The development of this plasmodium, includes; the
pre-erythrocytic and exco-erythrocytic cycles in the liver. Morphogically
unstained preparations show the vivax trophozoite to appear in the red blood
cells as a small disc, which becomes amoeboid with characteristic rapid
movement that justifies the name vivax.
The gametocyte show no evidence of
segmentation P. vivax has a striking
effect on the invaded red blood corpuscles that gradually enlarge and becomes
decolourized.
B. Plasmodium falciparum
Majority of death in sub-Saharan-Africa as well as in Ebonyi State
is as a result of P. facliparum
infect. One of the reasons why it continued to thrive is because the most
dangerous vectors of malaria parasite are Anopheles
funestus and Anopheles gambiae
exist here. Pre-erythrocytic schizonts of P.
falciparum release more menozoites than those of other species affecting
man. It is the Chief infection in areas of endemic malaria in Africa
because development in the mosquito is retarded when the temperature falls,
below 200C. Even at this temperature about 3 weeks are required for
the maturation of the sporozoites.
The asexual development of P. falciparum in the liver involves a
pre-erythrocytic phase there is no exo-erythrocytic phase giving rise to long
term relapses, such as occur in vivax and ovale. The young ring (trophozoites)
form of P.falciparum as seen in the
peripherial blood are very small, measuring about 1/6 of the diameter of a red
blood corpuscle. The mature schizont of P.
facliparum is smaller than that of any malaria parasite.
The distribution
of the parasite in organs of tissue of the human body varies on different
cases, this accounts for the diversity of clinical manifestation observed in
falciparum malaria. Most of the severe and fatal cases are due to blocking of
the capilliaties by clumps of red blood corpuscles harbouring developing
parasites.
C. Plasmodium malariae
This
is the causal organism of quartan malaria because the paroxysms of fever occur
every fourth day after two days interval. This parasite differs from the other
species affecting man by it morphological characters which indicates that it is
characterized by a compact parasite (call stages) and does not alter the host
erythrocyte or cause enlargement or development in both human and insect host.
The cause of the disease is not unduly severe but its long persistence is
notorious. It causes glomeruloephritis and nephritic syndrome in children.
Atkinson (1987) described the fine structure of the erythrocytic stages of P. malaria.
D. Pasmodium ovale;
This is the least common of the species that affect man. Diagnostically, the
sporozite stage is plump, elongated and pointed at one end. The schizonts are large
and quite distinctive. It has numerous nuclei. P. ovale produces fever similar to that of vivax malaria but often
with prolonged latency lesser tendency to relapse and generally milder clinical
symptoms.
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