''Plasmodium eylesi'' is a parasite of the genus ''

Plasmodium ''Plasmodium'' is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of ''Plasmodium'' species involve development in a blood-feeding insect host which then injects parasites into a ver ...

'' subgenus ''

''. Like all ''Plasmodium'' species ''P. eylesi'' has both

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

and

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

hosts. The vertebrate hosts for this parasite are mammals.

Description

The parasite was first described by Warren ''et al.'' in 1965.Warren McW., Bennett G.F., Sandosham A.A. and Coatney G.R. (1965) ''Plasmodium eylesi'' sp. nov., a tertian malaria parasite from the white-handed gibbon, ''Hylobates lar''. Ann. Trop. Med. Parasit. 59: 500-508Warren, McW., Bennett, G.F., and Sandosham A.A., 1965. A new malaria parasite from the white-handed gibbon, ''Hylobates lar lar'' in Malaya. Singapore Med. J. 6:50 and is named after the malariologist Dr. Don E. Eyles, Father of the Apollo computer engineer Don Eyles. 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 Reticulocytes are immature red blood cells (RBCs). In the process of erythropoiesis (red blood cell formation), reticulocytes develop and mature in the bone marrow and then circulate for about a day in the blood stream before developing into ...

but will infect older

erythrocytes Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

. Multiple infections like those of '' Plasmodium falciparum'' are common with up to six ring forms. Almost immediately on infection the

erythrocyte Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

enlarges.

Schüffner's dots Schüffner's dots refers to a hematological finding that is associated with malaria, exclusively found in infections caused by ''Plasmodium ovale'' or ''Plasmodium vivax''. ''Plasmodium vivax'' induces morphologic alterations in infected host ery ...

are rapidly apparent. Pigment is scarce, granular and yellowish-brown. Young

schizont Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

s almost fill the host cell except for small areas where Schüffner's dots may be found.

Oval An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas (projective geometry, technical drawing, etc.) it is given a more precise definition, which may include either one ...

shaped forms may occur. Each schizont may give rise to 20 - 34

merozoite Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

s (average: 25). The mature macrogametocytes which stain a grayish-blue fill the enlarged host cell. Also present is a coarse, granular

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compou ...

which is scattered evenly throughout the parasite. The generally oval

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

is deep staining and may have an adjacent

vacuole A vacuole () is a membrane-bound organelle which is present in 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 m ...

. 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 In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...

. The mature

oocytes An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female g ...

in the mosquito average 53

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s (µm) in size (range: 27 to 69 µm).

Sporozoite Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...

s appear in the salivary glands between day 9 and 10 and are infectious by day 12.

Geographical occurrence

This species is found in

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Clinical features and host pathology

Vertebrate hosts include the white-handed gibbon (''

Hylobates lar The lar gibbon (''Hylobates lar''), also known as the white-handed gibbon, is an endangered primate in the gibbon family, Hylobatidae. It is one of the better-known gibbons and is often kept in captivity. Taxonomy There are five subspecies of ...

''). Mosquito vectors of this parasite include '' Anopheles introlatus'', '' Anopheles kochi'', '' Anopheles lesteri'', '' Anopheles letifer'', '' Anopheles leucosphyrus'', ''

Anopheles maculatus ''Anopheles'' () is a genus of mosquito first described and named by J. W. Meigen in 1818. About 460 species are recognised; while over 100 can transmit human malaria, only 30–40 commonly transmit parasites of the genus ''Plasmodium'', which c ...

'', '' Anopheles roperi'', '' Anopheles riparis macarthuri'', '' Anopheles sinensis'', ''

Anopheles sundaicus ''Anopheles sundaicus'' is a zoophilic mosquito of southeast Asia. Species complex Sukowati et al. 1999 finds there to be several cryptic species in an ''An. sundaicus'' complex. They use protein electrophoresis to reveal populations defined by ...

'', '' 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 ''Plasmodium cynomolgi'' is an apicomplexan parasite that infects mosquitoes and Asian Old World monkeys. In recent years, a number of natural infections of humans have also been documented. This species has been used as a model for human ''Plas ...

'' 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.Tsukamoto M. (1977) An imported human malarial case characterized by severe multiple infections of the red blood cells. Ann. Trop. Med. Parasit. 19(2)95-104

References

{{DEFAULTSORT:Plasmodium Eylesi eylesi