TYPES OF MALARIAL PARASITES1.PLASMODIUM VIVAX2.PLASMODIUM FALCIPARUM3.PLASMODIUM MALARIAE4.PLASMODIUM OVALE

PLASMODIUM VIVAX

• Vivax - actively motile trophozoite• It has widest geographical distribution,it accounts for 80% of all

malarial infections.• It is common in asia and america and less common in africa.• It causes benign tertian malaria with few relapses.

PLASMODIUM VIVAX

Sporozoites of p.vivax are narrow and slightly curved. On entering hepatic cell some develops into exoerythrocytic schizonts

and some into hypnozoites. There may be two types of sporozoites 1.tachysporozoites 2.brady sporozoites.the merogony lasts for 8 days avg no. of merozoites 10,000.Erythrocyte preference - reticulocytes and young R.B.C.ALL STAGES ARE FOUND IN THE PEREFERAL BLOOD

PLASMODIUM VIVAX

Ring stage:it is well defined with a prominent central vacuole, one side of ring is thicker and other side is thin, where the nucleus is situated.it is about 1/3 of size of R.B.C.

The infected R.B.C show schuffner’s dots The schizont appears in 36-40hr.it occupies whole of the enlarged red

cell. The schizont mature in the next 6-8 hr with the development of merozoites each with central nucleus and surrounding cytoplasm.this stage presents a rosette appearance. There are 12-24 merozoites per schizont.

Erythrocytic schizogony –48hr. The red cell which now measures about 10 micro meter in diameter is heavily stippled and often distorted it bursts to liberate the merozoite and pigment .

Merozoite- 1.5 micro meter and no pigment. Gametocytes usually appear with in 4 days after the trophozoites first

appear. Macrogametocyte-dense cytoplasm staining deep blue and a small

compact nucleus Microgametocyte –pale staining cytoplasm and a large diffuse nucleus.

Plasmodium Vivax

Plasmodium falciparum

Falciparum-sickle shaped gametocytes. It is highly pathogenic of all the plasmodia and hence the name

malignant tertian or pernicious malaria. Schizogony- the sporozoites are sickle shaped. No hypnozoite

occur.mature liver schizont releases 30,000 merozoites. R.B.C preference young erythrocytes and also infect all stages of

erythrocytes. Only rings and gametocytes are seen in peripheral blood

Ring form- delicate , small ,1.5 micrometer, double chromatin and multiple rings are common resembling stereo headphones in appearance.

The presence of p.falciparum schizonts in peripheral smear indicates bad prognosis.

The mature schizont is smaller and has 8-24 merozoites. The erythrocytic schizogony takes about 48hrs or less.

Very high intensity of parasitization (may even up to 50%)

Plasmodium falciparum

Plasmodium malariae

This was the first malarial parasite discovered and is discovered by laveran in 1880 and the name malariae Is given by him.

It cause QUARTAN malariae. The disease is generally mild but is notorious for it’s long persistence

in circulation in undetectable levels for 50 years or more.Recrudescence may be provoked by splenectomy or immune suppression.

The development of the parasite in mosquito and man is much slower.chimpanzees may be naturally infected with p.malariae and may constitute a natural reservoir.

It occurs in tropical africa,srilanka,burma and parts of INDIA. Sporozoites are relatively thick.merogony takes about 15 days. Each

schizont releases 15,000 merozoites. Hypnozoites do not occur. The long latency – due to persistence of small no. of erythroctic forms

in some internal organs.

R.B.C preference old erythrocytes and low degree of parasitization. All forms seen in peripheral blood.

Ring forms—resemble those of p.vivax although thicker and more intensely stained.old trophozoites are sometimes seen stretched across the R.B.C as a broad band which is unique feature of p.malariae.

Numerous large pigment granules are seen in ring forms

The schizont appears in 50hrs and mature during next 18hrs.mature schizont has an average of 8 merozoites, which usually present as a ROSETTE appearance

The infected R.B.C are of normal size or slightly smaller. Fine stippling called ziemann’s stippling may be seen with special stains.erythrocytic schizogony takes 72hrs.

Gametocytes develop In internal organs and appear in peripheral circulation.

Microgametocyte-pale blue cytoplasm with large diffuse nucleus. Macrogametocyte-deep blue cytoplasm and a small compact nucleus.

Plasmodium malariae

Plasmodium ovale

Ovale-oval appearance of infected erythrocyte. It produces tertian fever resembling p.vivax but with milder

symptoms,prolonged latency and fewer relapses. It is the rarest of all plasmodia and is seen mostly in tropical africa

particularly along the west coast The merogony extends for 9 days. Hepatocytes contains schizonts

usually have enlarged nuclei. The mature liver schizont releases about 15,000 merozoites. Hypnozoites are present.

The trophozoites resemble those in p.vivax but are usually more compact with less amoeboid appearance. Schuffner’s dots appears earlier and are more abundant and prominent than in p.vivax.

The infected erythrocytes are slightly enlarged in thin films, many of them present an oval shape with fimbriated margins.

The schizont resemble those of p.malariae except the pigment is darker and R.B.C is usually oval prominent with schuffner’s dots.

Micro and macrogametocytes resembles vivax.

Plasmodium ovale

Mixed Infections

In endemic areas it is common to find mixed infections with 2 or more species of malaria parasite in the same individual.

Most common combination of mixed infection with p.vivax and p.falciparum.

The clinical picture may be atypical with bouts of occurring daily. Diagnosis made by demonstrating characteristic parasitic forms in thin

films.

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