Plasmodium fieldi
Encyclopedia
Plasmodium fieldi is a parasite of the genus Plasmodium
sub genus Plasmodium
found in Malaysia.
This species is related to Plasmodium ovale
and Plasmodium simiovale. Like all Plasmodium species P. fieldi has both vertebrate
and insect
hosts. The vertebrate hosts for this parasite are primate
s.
The asexual cycle is 48 hours in length
Ring forms: These measure about 3 micrometres in diameter and double chromatin bodies may be present. Multiple infections of the erythrocyte are uncommon.
Trophozoites: The cytoplasm
is compact, staining a deep blue while the nucleus
stains deep red. Pigment
is dark and made up of fine grains. Schüffner-type stippling also taking a deep red stain appears about half way though this stage. Older trophozoites are compact, rounded or oval and display very little amoeboidity. The vacuole
may be diminished or lost. Aggregates of dark eosinophilic masses sometimes larger than the nuclei may be present. Some host cells are oval-shaped and may be slightly enlarged.
Schizonts: Immature forms have dense blue-staining cytoplasm and relatively large deep red nuclei. The pigment is granular, well distributed and generally black in colour. Heavy stippling is present. As schizogony proceeds, the eosinophilic masses approximate forming a deep red border around the developing schizont. At this stage the host cell may be appreciably enlarged and some may assume an oval shape. Mature schizonts produce 4 to 16 (mean 12) large merozoites. The golden brown pigment forms a large mass in the center of the schizont. The host cell may become greatly distorted. This characteristic distortion appears to be distinctive for this parasite.
Gametocyte
s: Mature macrogametocytes have an off-centre, dark red nucleus. The deep blue cytoplasm has delicate, dark pigmentgranules scattered within it. The host cell, which may be slightly enlarged, has a red ring of eosinophilic stippling within it.
Mature microgametocytes occupy the entire the host cell and have dark pink cytoplasm. The off center nucleus stains red and has a deep red bar-like mass. Pigment granules are heavy and fairly evenly distributed in the cytoplasm. The host cells show a pronounced stippling and may have fimbriated edges.
Liver stages: These have been studied 6–14 days post infection. The exoerythrocytic bodies are circular to elliptical in shape and measure 20 micrometres in diameter at day 6 and 40-60 micrometres at day 14. The cytoplasm stains pale blue. The nucleus is about 1 micrometre in diameter. There are no morphological features to distinguish them from any other Plasmodium species.
The life cycle in the mosquito
has been studied in several species. Although the details differ somewhat between species the outline is broadly similar. The oocysts have a maximum diameter between 30 and 100 micrometres (mean 60 micrometres). Sporozoites appear in the salivary gland
s about day 14.
Transmission to human volunteers has not been successful.
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
sub genus Plasmodium
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
found in Malaysia.
This species is related to Plasmodium ovale
Plasmodium ovale
Plasmodium ovale is a species of parasitic protozoa that causes tertian malaria in humans. It is closely related to Plasmodium falciparum and Plasmodium vivax, which are responsible for most malaria. It is rare compared to these two parasites, and substantially less dangerous than P...
and Plasmodium simiovale. Like all Plasmodium species P. fieldi has both vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
hosts. The vertebrate hosts for this parasite are primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s.
Description
This species was first described by Eyles, Laing and Fong in 1962. The parasite was identified in a pig-tailed macaque (Macaca nemestrina) that Eyles purchased in peninsular Malaysia in mid-August 1960. It was named after the malariologist Dr. John W. Field.The asexual cycle is 48 hours in length
Ring forms: These measure about 3 micrometres in diameter and double chromatin bodies may be present. Multiple infections of the erythrocyte are uncommon.
Trophozoites: The cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
is compact, staining a deep blue while the nucleus
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
stains deep red. Pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
is dark and made up of fine grains. Schüffner-type stippling also taking a deep red stain appears about half way though this stage. Older trophozoites are compact, rounded or oval and display very little amoeboidity. The vacuole
Vacuole
A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain...
may be diminished or lost. Aggregates of dark eosinophilic masses sometimes larger than the nuclei may be present. Some host cells are oval-shaped and may be slightly enlarged.
Schizonts: Immature forms have dense blue-staining cytoplasm and relatively large deep red nuclei. The pigment is granular, well distributed and generally black in colour. Heavy stippling is present. As schizogony proceeds, the eosinophilic masses approximate forming a deep red border around the developing schizont. At this stage the host cell may be appreciably enlarged and some may assume an oval shape. Mature schizonts produce 4 to 16 (mean 12) large merozoites. The golden brown pigment forms a large mass in the center of the schizont. The host cell may become greatly distorted. This characteristic distortion appears to be distinctive for this parasite.
Gametocyte
Gametocyte
A gametocyte is a eukaryotic germ cell that divides by mitosis into other gametocytes or by meiosis into gametids during gametogenesis. Male gametocytes are called spermatocytes, and female gametocytes are called oocytes....
s: Mature macrogametocytes have an off-centre, dark red nucleus. The deep blue cytoplasm has delicate, dark pigmentgranules scattered within it. The host cell, which may be slightly enlarged, has a red ring of eosinophilic stippling within it.
Mature microgametocytes occupy the entire the host cell and have dark pink cytoplasm. The off center nucleus stains red and has a deep red bar-like mass. Pigment granules are heavy and fairly evenly distributed in the cytoplasm. The host cells show a pronounced stippling and may have fimbriated edges.
Liver stages: These have been studied 6–14 days post infection. The exoerythrocytic bodies are circular to elliptical in shape and measure 20 micrometres in diameter at day 6 and 40-60 micrometres at day 14. The cytoplasm stains pale blue. The nucleus is about 1 micrometre in diameter. There are no morphological features to distinguish them from any other Plasmodium species.
The life cycle in the mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
has been studied in several species. Although the details differ somewhat between species the outline is broadly similar. The oocysts have a maximum diameter between 30 and 100 micrometres (mean 60 micrometres). Sporozoites appear in the salivary gland
Salivary gland
The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
s about day 14.
Transmission to human volunteers has not been successful.
Vectors
- Anopheles (Nyssorhynchus) albimanusAnopheles albimanusAnopheles albimanus is a species of mosquito.-Habitat:Larvae of this species live in a wide range of permanent freshwater habitats. They are, however, salt tolerant. They live in sites that contain abundant amounts of floating, emergent vegetation. The larvae can also live in floating algae and scum...
- Anopheles (Anopheles) argyropus
- Anopheles (Anopheles) atroparvus
- Anopheles (Cellia) balabacensis balabacensis
- Anopheles (Cellia) balabacensis introlatus
- Anopheles (Cellia) dirusAnopheles dirusAnopheles dirus is a vector of malaria in Asian forested zones.-Taxonomy:It is often seen as a species complex including at least seven closely related and efficient forest-based malaria vectors in Asia. Hence, its geographical distribution is overlapping with areas of high malaria prevalence rates...
- Anopheles (Anopheles) donaldi
- Anopheles (Anopheles) freeborni
- Anopheles (Cellia) hackeri
- Anopheles (Cellia) kochi
- Anopheles (Anopheles) letifer
- Anopheles (Cellia) maculatus
- Anopheles (Anopheles) peditaeniatus
- Anopheles (Cellia) philippinensis
- Anopheles (Anopheles) quadrimaculatus
- Anopheles (Anopheles) sinensis
- Anopheles (Cellia) stephensiAnopheles stephensiAnopheles albimanus is a species of mosquito....
- Anopheles (Cellia) vagus