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A
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A
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A:
Normal red blood cell and ring-form trophozoites (rings) of P. knowlesi. Fig. 1: Normal red cell; Figs. 2-10: Increasingly mature ring-form parasites.
Early ring-form
trophozoites (rings) of P. knowlesi are similar to P. falciparum,
as rings may show double chromatin dots. Appliqué
forms may appear, as well as rectangular rings harboring one or more
accessory chromatin dots. Red blood cells may also be
multiply-infected. When full-grown, non-amoeboid rings may occupy half
or more of the host RBC.
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| A | B |
A,
B:
Ring-form trophozoites of P. knowlesi in a Giemsa-stained thin blood
smear from a human patient that traveled to the Philippines. Note a
multiply-infected RBC in Figure A. Images courtesy of the
Wadsworth Center, New York State Department of Health.
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| C | D |
C,
D:
Ring-form trophozoites of P. knowlesi in a Giemsa-stained thin blood
smear from a human patient that traveled to the Philippines. Note a
multiply-infected RBC in Figure C. Images courtesy of the
Wadsworth Center, New York State Department of Health.
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| E | F |
E, F:
Ring-form trophozoites of P. knowlesi in a Giemsa-stained thin blood
smear from a human patient that traveled to the Philippines. Note a
multiply-infected RBC in Figure F. Images courtesy of the
Wadsworth Center, New York State Department of Health.
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| A |
A:
Developing trophozoites of P. knowlesi. Figs. 11-12: Developing
trophozoites; Figs. 13-15: Mature trophozoites.
In developing
trophozoites of P. knowlesi, band forms may appear that are similar
in appearance to P. malariae. As the vacuole is lost during
maturation of the trophozoite stage, the parasite becomes smaller and more
compact. The pigment appears as dark grains and the red nucleus
increases in size. Stippling appears, often referred to as 'Sinton and
Mulligan's' stippling, as it is not of the Schüffner
type.
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| A | B |
A: Band-form
trophozoite of P. knowlesi in a Giemsa-stained thin blood smear from
a human patient that traveled to the Philippines. Image courtesy of
the Wadsworth Center, New York State Department of Health.
B: Band-form (upper) and ring-form (lower) trophozoites of P. knowlesi, from the same specimen as Figure A.
B: Band-form (upper) and ring-form (lower) trophozoites of P. knowlesi, from the same specimen as Figure A.
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| A |
A:
Gametocytes of P. knowlesi.
Fig. 24: Mature
macrogametocyte; Fig. 25: Mature microgametocyte.
In developing
schizonts, Sinton and Mulligan's stippling may be observed. The
nucleus continues to divide until there are up to 16 (average 10)
merozoites. As the schizont matures, it fills the host RBC and the
pigment collects into one or a few masses. In the mature schizont, the
merozoites may appear 'segmented' and the pigment has collected into a
single mass.
 |
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| A | B |
A,
B: Mature
schizonts in a Giemsa-stained thin blood smear from a patient that traveled
to the Philippines. Note also a ring-form trophozoite to the right of
the schizont in Figure B. Images courtesy of the Wadsworth
Center, New York State Department of Health.
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| C | D |
C: Developing
schizont in a Giemsa-stained thin blood smear from the same patient seen in
Figures A and B.
D: Mature schizont in a Giemsa-stained thin blood smear from the same patient seen in Figures A-C.
D: Mature schizont in a Giemsa-stained thin blood smear from the same patient seen in Figures A-C.
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| E |
E: Developing schizont in a
Giemsa-stained thin blood smear from the same patient as Figures A-D.
Mature
macrogametocytes of P. knowlesi are usually spherical and fill the
host RBC. The cytoplasm stains blue and the eccentric nucleus stains
red. Pigment is coarse and black, and is scattered irregularly in the
cytoplasm. The microgametocyte is often, but not always, smaller than
the macrogametocyte. The cytoplasm usually stains a pale pink, while
the nucleus stains a darker red. The nucleus may make up half the parasite.
The coarse, black pigment is scattered irregularly thought the cytoplasm.
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| A | B |
A,
B: Gametocytes
of P. knowlesi in a Giemsa-stained thin blood smear from a patient
that traveled to the Philippines. Note also a ring-form trophozoite in
the lower left of Figure B. Images courtesy of the Wadsworth
Center, New York State Department of Health.
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| A |
A:
Schizonts of P. knowlesi. Figs. 16-20: Developing
schizonts. Figs. 20-22: Nearly mature schizonts.
Fig. 23: Mature schizont.
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