Plasmodium

Question 1

Plasmodium falciparum

Answer 1

infected blood cells are normal size

only trophozoites and gametocytes seen

no schuffners dots but cells containing late stage trophozoites usually contain maurers clefts

cells may contain multiple parasites

many parasites may be present

most widespread

usually die out within 1 year of primary attack

Question 2

Plasmodium malariae

Answer 2

found in tropics and subtropics

low prevalence

can persist for many years after an attack

rarely more than 1% of cells become parasitised

trophozoites, schizonts and gametocytes can be seen

host red cell not enlarged and no schuffners dots or maurers clefts

rare for more than one parasite to parasitise a cell

Question 3

Plasmodium vivax

Answer 3

most widespread in temperate regions and in subtropics

parasite forms hypnozoites causing relapses - usually dies out within 3 to 5 years of initial attack

parasites invade immature red cells

trophozoites, schizonts and gametocytes can be seen

host cell enlarged and irregular in shape

schuffners dots present

Question 4

Plasmodium ovale

Answer 4

found mainly in west africa

low prev

parasites form hypnozoites but relapses are few

rarely more than 2% of cells infected

trophozoites, schizonts and gametes seen

20-30% cells become fimbriated and are slightly enlarged

Question 5

Answer 5

Plasmodium falciparum trophozoite

mainly small and delicate rings (thin film) or small pieces of cytoplasm with chromatin dot in thick film

may have a double chromatin dot

rbc normal size and shape

high levels of parasitaemia

accole form on the surface of the rbc

multiple invasion

red chromatin dot and blue cytoplasm

Question 6

Answer 6

Plasmodium falciparum gametocyte

crescent shaped gametocyte

haemozoin seen around the nucleus

nucleus stained purple and cytoplasm stained blue

Question 7

Answer 7

Plasmodium malariae trophozoite

rbc normal sized or microcytic

no schuffners or maurers

trophozoites are thick, compact and densely stained

characteristic band forms

thickened cytoplasmic ring

birds eye form with chromatin dot in centre of cytoplasm

Question 8

Answer 8

Plasmodium malariae schizont

early schizont - enlarged parasite - chromatin divided into two or more discrete areas but cytoplasm not divided - pigment present

mature - 6-12 merozoites in rosette form with coarse pigment clump in the centre

Question 9

Answer 9

Plasmodium malariae gametocyte

round or oval with coarse dark pigment

nucleus usually lies to one side

dark brown pigment easily seen

Question 10

Answer 10

Plasmodium vivax trophozoite

red blood cells slightly enlarged

schuffners dots present in all stages except early ring form

occasional multiple invasion

amoeboid common

fine pigment granules may be seen in the cytoplasm

squiggly apart from early ring

half to third of the cell with heavy chromatin dot

Question 11

Answer 11

Plasmodium vivax schizont

developing schizont has enlarged parasite with chromatin divided into two or more discrete red areas but cytoplasm not divided and pigment present

large, round or irregular in form

12 to 24 merozoites in rosette filling the whole RBC with central pigment

Question 12

Answer 12

Plasmodium vivax gametocyte

round or oval shape

contains scattered pigment granules

Question 13

Answer 13

Plasmodium ovale trophozoite

RBC larger than normal and some have fimbriation

schuffners dots present

occasional multiple infection

ring half to a third of the cell with heavy chromatin dot

Question 14

Answer 14

Plasmodium ovale schizont

8-12 merozoites in rosette

less pigment than malariae although similar

developing schizont has enlarged parasite with chromatin divided into two or more discrete red areas but cytoplasm not divided and pigment present

Question 15

Answer 15

Plasmodium ovale gametocyte

round or oval but smaller than vivax

nucleus usually lies to one side