TYPES OF MALARIAL PARASITES

PREPARED BY KIMS COLLEGE

1. TYPES OF MALARIAL
PARASITES
1.PLASMODIUM VIVAX
2.PLASMODIUM FALCIPARUM
3.PLASMODIUM MALARIAE
4.PLASMODIUM OVALE

2. PLASMODIUM VIVAX
•Vivax-actively motile trophozoite
•It has widest geographical distribution,itaccounts for 80% of all malarial
infections.
•It is common in asiaand americaand less common in africa.
•It causes benign tertian malaria with few relapses.

3. PLASMODIUM VIVAX
Sporozoitesof p.vivaxare narrow and slightly curved.
On entering hepatic cell some develops into exoerythrocyticschizontsand some
into hypnozoites.
There may be two types of sporozoites
 1.tachysporozoites
 2.brady sporozoites
.the merogonylasts for 8 days avgno. of merozoites10,000.
Erythrocyte preference -reticulocytesand young R.B.C.
ALL STAGES ARE FOUND IN THE PEREFERAL BLOOD

4. PLASMODIUM VIVAX
Ring stage:itis well defined with a prominent central vacuole, one side of ring is
thicker and other side is thin, where the nucleus is situated.itis about 1/3 of size
of R.B.C.
The infected R.B.C show schuffner’sdots
The schizontappears in 36-40hr.it occupies whole of the enlarged red cell. The
schizontmature in the next 6-8 hr with the development of merozoiteseach with
central nucleus and surrounding cytoplasm.thisstage presents a rosette
appearance. There are 12-24 merozoitesper schizont.

5. Erythrocyticschizogony–48hr. The red cell which now measures about 10 micro
meter in diameter is heavily stippled and often distorted it bursts to liberate the
merozoiteand pigment .
Merozoite-1.5 micro meter and no pigment.
Gametocytes usually appear with in 4 days after the trophozoitesfirst appear.
Macrogametocyte-dense cytoplasm staining deep blue and a small compact
nucleus
Microgametocyte –pale staining cytoplasm and a large diffuse nucleus.

6. Plasmodium Vivax

7. 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 sporozoitesare sickle shaped. No hypnozoiteoccur.mature
schizontreleases 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

8. Ring form-delicate , small ,1.5 micrometer, double chromatin and multiple rings
are common resembling stereo headphones in appearance.
The presence of p.falciparumschizontsin peripheral smear indicates bad
prognosis.
The mature schizontis smaller and has 8-24 merozoites. The erythrocytic
schizogonytakes about 48hrs or less.
Very high intensity of parasitization(may even up to 50%)

9. Plasmodium falciparum

10. Plasmodium malariae
This was the first malarial parasite discovered and is discovered by laveranin
1880 and the name malariaeIs 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.Recrudescencemay be
provoked by splenectomyor immune suppression.

11. The development of the parasite in mosquito and man is much
slower.chimpanzeesmay be naturally infected with p.malariaeand may constitute
a natural reservoir.
It occurs in tropical africa,srilanka,burmaand parts of INDIA.
Sporozoitesare relatively thick.merogonytakes about 15 days. Each schizont
releases 15,000 merozoites. Hypnozoitesdo not occur.
The long latency –due to persistence of small no. of erythrocticforms in some
internal organs.

12. R.B.C preference old erythrocytes and low degree of parasitization. All forms seen
in peripheral blood.
Ring forms—resemble those of p.vivaxalthough thicker and more intensely
stained.oldtrophozoitesare 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

13. The schizontappears in 50hrs and mature during next 18hrs.mature schizonthas
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’sstippling may be seen with special stains.erythrocyticschizogonytakes
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.

14. Plasmodium malariae

15. Plasmodium ovale
Ovale-oval appearance of infected erythrocyte.
It produces tertian fever resembling p.vivaxbut with milder symptoms,prolonged
latency and fewer relapses.
It is the rarest of all plasmodia and is seen mostly in tropical africaparticularly
along the west coast
The merogonyextends for 9 days. Hepatocytescontains schizontsusually have
enlarged nuclei. The mature liver schizontreleases about 15,000 merozoites.
Hypnozoitesare present.

16. The trophozoitesresemble those in p.vivaxbut are usually more compact with
less amoeboid appearance. Schuffner’sdots 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 fimbriatedmargins.
The schizontresemble those of p.malariaeexcept the pigment is darker and
R.B.C is usually oval prominent with schuffner’sdots.
Micro and macrogametocytesresembles vivax.

17. Plasmodium ovale

18. 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.vivaxand 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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