 |
| A |
Developing
schizonts of P. vivax are large and amoeboid. Chromatin is
arranged in two or more masses; pigment is also usually arranged in more
than one mass. Mature schizonts contain 12-24 merozoites, each of
which contains a dot of chromatin and a mass of cytoplasm. Pigment is
usually organized in one or two clumps. Like other stages, infected
RBCs are usually larger than uninfected RBCs.
 |
 |
| A | B |
A,
B: Schizonts of P. vivax in thin blood smears.
 |
 |
| C | D |
C: Schizont of P. vivax
in a thin blood smear.
D: Ruptured schizont of P. vivax in a thin blood smear, showing free merozoites and pigment.
D: Ruptured schizont of P. vivax in a thin blood smear, showing free merozoites and pigment.
Ring-form
trophozoites of P. vivax usually have a thick cytoplasm with a
single, large chromatin dot. Rings may be difficult to distinguish
from those of P. ovale. The cytoplasm becomes amoeboid and Schüffner's
dots may appear as the trophozoites mature. Infected RBCs are often
larger than uninfected RBCs. Multiply-infected RBCs are not uncommon.
 |
 |
| A | B |
A, B: Ring-form
trophozoites of P. vivax in thin blood smears.
 |
 |
| C | D |
C,
D: Ring-form trophozoites of P. vivax in thin blood smears.
 |
| E |
E: Ring-form
trophozoites of P. vivax in a thin blood smear.
----------------------------------------------------------------
Ring-form
trophozoites of P. vivax usually have a thick cytoplasm with a
single, large chromatin dot. Rings may be difficult to distinguish
from those of P. ovale. The cytoplasm becomes amoeboid and Schüffner's
dots may appear as the trophozoites mature. Infected RBCs are often
larger than uninfected RBCs. Multiply-infected RBCs are not uncommon.
 |
 |
| A | B |
A, B: Ring-form
trophozoites of P. vivax in a thick blood smear.
----------------------------
Developing
trophozoites of P. vivax become increasingly amoeboid, with tenuous
pseudopodial processes and large vacuoles. Schüffner's
dots are visible with proper staining. Pigment tends to be fine and
brown. Infected RBCs are usually noticeably larger than uninfected
RBCs.
 |
| A |
A:
Trophozoite of P. vivax in a thick blood smear.
Developing
trophozoites of P. vivax become increasingly amoeboid, with tenuous
pseudopodial processes and large vacuoles. Schüffner's
dots are visible with proper staining. Pigment tends to be fine and
brown. Infected RBCs are usually noticeably larger than uninfected
RBCs.
 |
 |
| A | B |
A, B:
Trophozoites of P. vivax in thin blood smears. Note the
amoeboid appearance, Schüffner's dots
and enlarged infected RBCs.
 |
 |
| C | D |
C, D: Trophozoites
of P. vivax in thin blood smears. Note the amoeboid
appearance, Schüffner's dots and
enlarged infected RBCs.
 |
 |
| E | F |
E, F: Trophozoites
of P. vivax in a thin blood smear. Note the band-like
appearance of the trophozoite in Figure F that may be mistaken
for a band-form trophozoite of P. malariae. Note however
the fine, light brown pigment that is distributed throughout the
cytoplasm (pigment in P. malariae is usually darker and coarser
and distributed on the periphery of the cytoplasm). The infected
RBCs are also noticeably larger than the uninfected RBCs.
 |
| A |
A:
Gametocytes of P. vivax. Fig. 28: Developing
macrogametocyte; Fig. 29: Mature macrogametocyte (female); Fig.
30: Mature microgametocyte (male).
Illustrations from:
Coatney GR, Collins WE, Warren M, Contacos PG. The Primate Malarias. Bethesda: U.S.
Department of Health, Education and Welfare; 1971.
acrogametocytes
of P. vivax are round to oval and usually fill the host cell.
The infected RBC is usually noticeably larger than uninfected RBCs.
The cytoplasm is usually a darker blue and contains fine brown pigment
throughout. Schüffner's dots may
be seen with proper staining. Microgametocytes are usually the size of
an uninfected RBC and have a paler blue, pink or gray cytoplasm.
 |
 |
| A | B |
A:
Gametocyte (upper) and trophozoite (lower) of P. vivax in a thick
blood smear.
B: Gametocyte of P. vivax in a thick blood smear.
B: Gametocyte of P. vivax in a thick blood smear.
Developing
schizonts of P. vivax are large and amoeboid. Chromatin is
arranged in two or more masses; pigment is also usually arranged in more
than one mass. Mature schizonts contain 12-24 merozoites, each of
which contains a dot of chromatin and a mass of cytoplasm. Pigment is
usually organized in one or two clumps. Like other stages, infected
RBCs are usually larger than uninfected RBCs.
 |
 |
| A | B |
A,
B: Schizonts of P. vivax in thick blood smears.
 |
 |
| C | D |
C, D: Schizonts of
P. vivax in thick blood smears.
 |
| E |
E: Schizont of P. vivax
in a thick blood smear.
---------------------
Macrogametocytes
of P. vivax are round to oval and usually fill the host cell.
The infected RBC is usually noticeably larger than uninfected RBCs.
The cytoplasm is usually a darker blue and contains fine brown pigment
throughout. Schüffner's dots may
be seen with proper staining. Microgametocytes are usually the size of
an uninfected RBC and have a paler blue, pink or gray cytoplasm.
 |
 |
| A | B |
A,
B: Macrogametocytes of P. vivax in thin blood smears.
Note the enlargement of the gametocytes compared to uninfected RBCs.
 |
 |
| C | D |
C,
D: Macrogametocytes of P. vivax in a thin blood smear.
Note the enlargement of the gametocytes compared to uninfected RBCs.
 |
 |
| E | F |
E, F:
Macrogametocytes of P. vivax in thin blood smears.
Developing
schizonts of P. vivax are large and amoeboid. Chromatin is
arranged in two or more masses; pigment is also usually arranged in more
than one mass. Mature schizonts contain 12-24 merozoites, each of
which contains a dot of chromatin and a mass of cytoplasm. Pigment is
usually organized in one or two clumps. Like other stages, infected
RBCs are usually larger than uninfected RBCs.
|
|
| A | B |
A,
B: Schizonts of P. vivax in thin blood smears.
|
|
| C | D |
C: Schizont of P. vivax
in a thin blood smear.
D: Ruptured schizont of P. vivax in a thin blood smear, showing free merozoites and pigmen
D: Ruptured schizont of P. vivax in a thin blood smear, showing free merozoites and pigmen
Ookinetes are
motile zygotes formed by the combination of macrogametocytes and
exflagellated microgametocytes in the mid-gut of the mosquito host.
Ookinetes invade epithelial cells of the mosquito's mid-gut where an oocyst
is formed. Ookinetes are not found in peripheral blood in the human
host and are very rarely found on blood smears. Their presence on
smears usually indicates a substantial delay occurred between the time the
blood was collected and the time the slide was prepared. The following
ookinetes were observed on a specimen courtesy of the Florida State
Department of Health. The patient had traveled to India.
 |
 |
| A | B |
A,
B: Ookinetes of P. vivax in a thick blood smear.
 |
 |
| C | D |
C: Ookinete of P. vivax
in a thick blood smear.
D: Ookinete of P. vivax in a thin blood smear.
D: Ookinete of P. vivax in a thin blood smear.
 |
| E |
E: Ookinete of P. vivax
in a thin blood smear.
 |
| A |
A:
Schizonts of P. vivax. Figs. 19-21: Early schizonts;
Figs. 22-24: Developing schizonts; Figs. 25-27: Nearly
mature to mature schizonts.
Illustrations from:
Coatney GR, Collins WE, Warren M, Contacos PG. The Primate Malarias. Bethesda: U.S.
Department of Health, Education and Welfare; 1971.
Malaria is transmitted by mosquitoes in the genus
Anopheles. These mosquitoes are not only vectors of malaria,
but also serve as the definitive host for Plasmodium spp., as the
sexual stages of the parasite take place in the mosquito.
Different species and species complexes of Anopheles transmit
malaria in different parts of the world. However, of the over 200
species of Anopheles in the world, less than half are vectors of
human malaria. Anopheline mosquitoes can be separated by other
genera by possessing palps that extend the same length as the proboscis.
Also, many anopheline mosquitoes assume a "head-stand" position when
taking a blood meal from the mammalian host.
 |
 |
| A |
B
|
A,
B:
Adults of A. freeborni.
 |
 |
| C |
D
|
C:
Adult of A. quadrimaculatus.
D: Close-up of the head of Anopheles sp., showing the length of the palps (red arrow) in relation to the proboscis (blue arrow).
D: Close-up of the head of Anopheles sp., showing the length of the palps (red arrow) in relation to the proboscis (blue arrow).
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