Plasmodium eylesi
Encyclopedia
Plasmodium eylesi is a parasite of the genus Plasmodium
subgenus Plasmodium
.
Like all Plasmodium species P. eylesi has both vertebrate
and insect
hosts. The vertebrate hosts for this parasite are mammal
s.
It is believed that this species is related to Plasmodium hylobati, Plasmodium jefferyi and Plasmodium youngi
but this putative relationship awaits examination by DNA
based methods.
The parasite prefers to infect reticulocytes but will infect older erythrocytes. Multiple infections like those of Plasmodium falciparum
are common with up to six ring forms.
Almost immediately on infection the erythrocyte enlarges. Schüffner's dots
are rapidly apparent. Pigment is scarce, granular and yellowish-brown.
Young schizonts almost fill the host cell except for small areas where Schüffner’s dots may be found. Oval
shaped forms may occur.
Each schizont may give rise to 20 - 34 merozoites (average: 25).
The mature macrogametocytes which stain stain a grayish-blue fill the enlarged host cell. Also present is a coarse, granular pigment
which is scattered evenly throughout the parasite. The generally oval nucleus
is deep staining and may have an adjacent vacuole
.
The mature microgametocytes are found within an enlarged, circular to oval, host cell and take a deep brilliant reddish-purple stain
. The nucleus stains slightly more deeply. Pigment is scattered throughout the cytoplasm
.
The mature oocytes in the mosquito average 53 micrometre
s (µm) in size (range: 27 to 69 µm). Sporozoites appear in the salivary glands between day 9 and 10 and are infectious by day 12.
(Hylobates lar).
Mosquito vectors of this parasite include Anopheles b. introlatus, Anopheles kochi, Anopheles lesteri, Anopheles letifer, Anopheles leucosphyrus, Anopheles maculatus, Anopheles roperi, Anopheles riparis macarthuri, Anopheles sinensis, Anopheles sundaicus, Anopheles umbrosus and Anopheles vagus.
One case of possibly human infection is known. In 1968 Dr Gordon F. Bennett was bitten by an infected Anopheles kochi. After 15 days he developed a fever. Parasites were evident in his blood for a week. It was not possible to transfer the infection to a gibbon. Doubts remain about the cause of the fever because Dr Bennett had previous been infected by Plasmodium cynomolgi which is not known to be infectious to gibbons.
A second case reported in 1977 may have been a case of P. eylesi but the author was not certain of the infecting species.
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...
subgenus 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...
.
Like all Plasmodium species P. eylesi 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 mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s.
Description
The parasite was first described by Warren et al. in 1965. and is named after the malariologist Dr. Don E. Eyles.It is believed that this species is related to Plasmodium hylobati, Plasmodium jefferyi and Plasmodium youngi
Plasmodium youngi
Plasmodium youngi is a parasite of the genus Plasmodium subgenus Plasmodium.Like all Plasmodium species P. youngi has both vertebrate and insect hosts. The vertebrate hosts for this parasite are mammals....
but this putative relationship awaits examination by DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
based methods.
The parasite prefers to infect reticulocytes but will infect older erythrocytes. Multiple infections like those of Plasmodium falciparum
Plasmodium falciparum
Plasmodium falciparum is a protozoan parasite, one of the species of Plasmodium that cause malaria in humans. It is transmitted by the female Anopheles mosquito. Malaria caused by this species is the most dangerous form of malaria, with the highest rates of complications and mortality...
are common with up to six ring forms.
Almost immediately on infection the erythrocyte enlarges. Schüffner's dots
Schüffner's dots
Schüffner's dots refers to a hematological finding that is associated with malaria, exclusively found in Plasmodium ovale and Plasmodium vivax....
are rapidly apparent. Pigment is scarce, granular and yellowish-brown.
Young schizonts almost fill the host cell except for small areas where Schüffner’s dots may be found. Oval
Oval
An oval is any curve resembling an egg or an ellipse, such as a Cassini oval. The term does not have a precise mathematical definition except in one area oval , but it may also refer to:* A sporting arena of oval shape** a cricket field...
shaped forms may occur.
Each schizont may give rise to 20 - 34 merozoites (average: 25).
The mature macrogametocytes which stain stain a grayish-blue fill the enlarged host cell. Also present is a coarse, granular 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...
which is scattered evenly throughout the parasite. The generally oval 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...
is deep staining and may have an adjacent 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...
.
The mature microgametocytes are found within an enlarged, circular to oval, host cell and take a deep brilliant reddish-purple stain
Stain
A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. Stains are caused by the chemical or physical interaction of two dissimilar materials...
. The nucleus stains slightly more deeply. Pigment is scattered throughout 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...
.
The mature oocytes in the mosquito average 53 micrometre
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s (µm) in size (range: 27 to 69 µm). Sporozoites appear in the salivary glands between day 9 and 10 and are infectious by day 12.
Clinical features and host pathology
Vertebrate hosts include the white-handed gibbonGibbon
Gibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related...
(Hylobates lar).
Mosquito vectors of this parasite include Anopheles b. introlatus, Anopheles kochi, Anopheles lesteri, Anopheles letifer, Anopheles leucosphyrus, Anopheles maculatus, Anopheles roperi, Anopheles riparis macarthuri, Anopheles sinensis, Anopheles sundaicus, Anopheles umbrosus and Anopheles vagus.
One case of possibly human infection is known. In 1968 Dr Gordon F. Bennett was bitten by an infected Anopheles kochi. After 15 days he developed a fever. Parasites were evident in his blood for a week. It was not possible to transfer the infection to a gibbon. Doubts remain about the cause of the fever because Dr Bennett had previous been infected by Plasmodium cynomolgi which is not known to be infectious to gibbons.
A second case reported in 1977 may have been a case of P. eylesi but the author was not certain of the infecting species.