''Hepatocystis'' is a genus of parasites transmitted by midges of the genus '' Culicoides''. Hosts include Old World

primates Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most bi ...

hippopotamus The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extan ...

and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoen, 1932, as ''Hepatocystes''.

Taxonomy

The type species is ''Hepatocystis kochi''. There are currently 25 recognised species in this genus.

Species list

* '' Hepatocystis bainae'' * '' Hepatocystis bouillezi'' * '' Hepatocystis brayi'' * '' Hepatocystis brosseti'' * '' Hepatocystis carpenteri'' * ''

Hepatocystis cercopitheci ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoen ...

'' * '' Hepatocystis epomophori'' * ''

Hepatocystis fieldi ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoen ...

'' * ''

Hepatocystis foylei ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoen ...

'' * ''

Hepatocystis garnhami ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * '' Hepatocystis hipposideri'' * ''

Hepatocystis hippopotami ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis kochi ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis levinei ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis limnotragi ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis malayensis ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * '' Hepatocystis muuli'' * '' Hepatocystis perronae'' * '' Hepatocystis pteropti'' * ''

Hepatocystis ratufae ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * '' Hepatocystis rodhaini'' * ''

Hepatocystis semnopitheci ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis simiae ''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''Culicoides''. Hosts include Old World primates, bats, hippopotamus and squirrels. This genus is not found in the New World. The genus was erected by Levaditi and Schoe ...

'' * ''

Hepatocystis taiwanensis ''Hepatocystis taiwanensis'' is a species of parasitic protozoa. They are transmitted by flies of the genus '' Culicoides'' and infect monkeys. Taxonomy This species was described in 1941 by Yokogawa in Formosan rock macaque (''Macaca cyclopis ...

'' * ''

Hepatocystis vassali ''Hepatocystis vassali'' is a species of parasitic protozoa that infect mammals. Taxonomy The parasite was first described by Laveran in 1905. Hosts The only known host is the red-bellied squirrel (''Callosciurus flavimanus Pallas's s ...

History

The first observation of malaria in bats dates to the end of the 19th century when Dionisi described gametocytes in the blood of a bat in 1898. The type species of this genus (''Hepatocystis kochi'') was described by Laveran in 1899 from the blood of a primate and he named it ''Plasmodium kochi''.

Life cycle

The protozoa are transmitted by the bite of the insect vector. The sporozoites migrate to the liver where they typically form merocysts within the liver parenchyma. These may also develop in the spleen and lungs. Macroscopically these may appear as white to gray nodular foci within the tissue. These lesions within these organs are characterized by well-circumscribed focal fibrosis, accumulation of eosinophils and histiocytes,

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

or hemosiderosis with the loss of normal architecture. The cystlike exoerythrocytic schizonts are found within the merocysts. These are found around the edges of the merocytes in huge numbers. The central core of the cyst consists of a non-cellular granular material. Released merozoites either invade other hepatocytes or erythrocytes. Within the erythrocytes the merozoites first become ring forms, then trophozoites and finally

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''. Development ...

s. The gametocytes are huge and fill the entire erythrocyte. Like those of ''

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 vert ...

'' and unlike those of ''

Hepatozoon ''Hepatozoon'' is a genus of Apicomplexa alveolates which incorporates over 300 species obligate intraerythrocytic parasites. Species have been described from all groups of tetrapod vertebrates, as well as a wide range of haematophagous arthropod ...

'' their nuclei are

Feulgen Feulgen stain is a staining technique discovered by Robert Feulgen and used in histology to identify chromosome, chromosomal material or DNA in cell specimens. It is darkly stained. It depends on acid hydrolysis of DNA, therefore fixating agents us ...

negative.

Haemozoin Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as malaria parasites (''Plasmodium spp.''), ''Rhodnius'' and '' Schistosoma'' digest haemoglobin and release hig ...

may be found within the erythrocytes. Infected erythrocytes are then taken up when the insect vector feeds on the host. Within the vector the sporogonic cycle lasts between 5–6 days. The

oocyst 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 i ...

s develop in the haemocoele chiefly in the head near the brain and eye.

Pathology

The mature merocysts are visible to the naked eye on the hepatic surface. These appear as raised, grayish-white to translucent foci with a central accumulation of fluid. Multiple, depressed areas of fibrosis with calcification representing healed lesions may also be found. Microscopically the liver cysts have an irregular central space filled with faintly eosinophilic, acellular, flocculent material. Surrounding this is a peripheral rim of myriad, round, lightly basophilic

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 which measure ~1.0–2.0 mm in diameter. The cysts themselves are delineated by a thin, convoluted, eosinophilic, hyaline capsule. A significant inflammatory response to the merocysts may or may not be present. If a reaction is present, it is typically granulomatous with an admixture of eosinophils and

lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...

s. The first appearance in the blood is normally two months after infection. The only stage seen in the blood are gametocytes. These double in number for the first three days and mature. Having reached maturity, they gradually decline in number and normally disappear after a month. Secondary episodes may occur at variable intervals. The early gametocytes consist of minute dense spots of chromatin with a tiny loop of cytoplasm. As the parasite grows, the chromatin tends to spread in a semicircle or into multiple dots. There is no stippling of the erythrocyte. Mature gametocytes are larger than a normal erythrocyte stain poorly compared to other protozoa. In both male and female gametocytes, the nucleus consists of two portions. The macrogametocyte is a steel blue color measuring 9.5 micrometres in diameter. The nucleus has a pale pink area with dense chromatin in the middle and is much smaller than that of the microgametocyte. The microgametocyte stains less densely, is biscuit-colored and measures 9.0 micrometres in diameter. The nucleus is a large, oval, pale pink area occupying one-third to one-half of the parasite.

Clinical features

In endemic areas, the incidence can range from 24 to 75% in nonhuman primates. Although infection with ''Hepatocystis'' does not normally cause fever it may cause anaemia in the host. Some versions of the

Duffy antigen Duffy antigen/chemokine receptor (DARC), also known as Fy glycoprotein (FY) or CD234 (Cluster of Differentiation 234), is a protein that in humans is encoded by the ''ACKR1'' gene. The Duffy antigen is located on the surface of red blood cells, ...

have been associated with protection from ''Hepatocytis'' infection in yellow baboons (''

Papio cynocephalus The yellow baboon (''Papio cynocephalus'') is a baboon in the family of Old World monkeys. The species epithet means "dog-head" in Greek, due to the dog-like shape of the muzzle and head. Yellow baboons have slim bodies with long arms and legs, a ...

'').

Host records

Primates and bats are the most commonly identified host of these parasites. ''H. bouillezi'', ''H. cercopitheci'', ''H. kochi'' and ''H. simiae'' infect

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

n monkeys. ''H. semnopitheci'' and ''H. taiwanensis'' infect

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

n monkeys. These species may lie in different phylogenetic clades but this is not yet known.

Hosts where parasite species is known

* ''H. bainae'' — Cantor's roundleaf bat (''

Hipposideros galeritus Cantor's roundleaf bat (''Hipposideros galeritus'') is a species of bat in the family Hipposideridae. It is found in Bangladesh, Brunei, Cambodia, India, Indonesia, Laos, Malaysia, Sri Lanka, Thailand and Vietnam. It is named after Theodore Edwa ...

'') * ''H. bouillezi'' — mona monkey (''

Cercopithecus mona The mona monkey (''Cercopithecus mona'') is an Old World monkey that lives in western Africa between Ghana and Cameroon. The mona monkey can also be found on the island of Grenada as it was transported to the island aboard slave ships headed to ...

'') * ''H. brosseti'' — Franquet's epauletted fruit bat (''

Epomops franqueti Franquet's epauletted fruit bat (''Epomops franqueti'') is a species of megabat in the family Pteropodidae, and is one of three different species of epauletted bats. Franquet's epauletted fruit bat has a range of habitats, varying from Subsaharan ...

'') * ''H. carpenteri'' — hammerhead bat ('' Hypsignathus monstrosus'') * ''H. cercopitheci'' — De Brazza's monkey (''

Cercopithecus neglectus De Brazza's monkey (''Cercopithecus neglectus'') is an Old World monkey endemic to the riverine and swamp forests of central Africa. The largest species in the guenon family, it is one of the most widespread arboreal African primates. Aside from ...

'') and greater spot nosed monkey (''

Cercopithecus nictitans The greater spot-nosed monkey or putty-nosed monkey (''Cercopithecus nictitans'') is one of the smallest Old World monkeys. It is a guenon of the '' C. mitis'' group, native to West Africa and living to some extent in rain forests, but more often ...

''). * ''H. epomorphori'' — fruit bat ('' Epomorphorus gambianus'') * ''H. garnhami'' — greater short nosed fruit bat (''

Cynopterus sphinx The greater short-nosed fruit bat (''Cynopterus sphinx''), or short-nosed Indian fruit bat, is a species of megabat in the family Pteropodidae found in South and Southeast Asia. Description These bats have a relatively long snout. Their upper pa ...

'') * ''H. hippopotami'' — hippopotamus ('' Hippopotamus amphibius'') * ''H. hipposideri'' — large leafnosed bat ('' Hipposideros armiger terasensis''). * ''H. kochi'' — African green monkeys ('' Cercopithecus aethiops''), black mangabey ('' Cercocebus aterrimus''), black crested gibbon (''

Hylobates concolor The black crested gibbon (''Nomascus concolor'') is a Critically Endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies. Taxonomy The taxonomy of the species is confused. Previously grouped in the genu ...

'') * ''H. levinei'' — grey-headed flying-fox (''

Pteropus poliocephalus The grey-headed flying fox (''Pteropus poliocephalus'') is a megabat native to Australia. The species shares mainland Australia with three other members of the genus Genus ( plural genera ) is a taxonomic rank used in the biological classifi ...

'') * ''H. muuli'' — Berdmore's ground squirrel ('' Menetes berdmorei'') * ''H. perronnae'' —

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n fruit bat ('' Lissonycteris angolensis''), little collared fruit bat ('' Myonycteris torquata''), * ''H. pteropi'' — bat ('' Cynopterus bracyotis''), Horsefield's fruit bat (''

Cynopterus horsfieldi Horsfield's fruit bat (''Cynopterus horsfieldii'') is a species of megabat native to South East Asia. It is named for Thomas Horsfield, an American naturalist who presented the type specimen to the British Museum. Description Horsfield's fruit ba ...

''), bat ('' Pteropus colinus''), common flying fox ('' Pteropus edwarsii''), spectacled flying fox (''

Pteropus conspicillatus The spectacled flying fox (''Pteropus conspicillatus''), also known as the spectacled fruit bat, is a megabat that lives in Australia's north-eastern regions of Queensland. It is also found in New Guinea and on the offshore islands including Wood ...

''), fruit bat ('' Pteropus geddiei''), black flying fox ('' Pteropus gouldi''), grey-headed flying fox (''

''), little red flying fox ('' Pteropus sacpulatus'') * ''H. rhodiani'' — bat (''

'') * ''H. simiae'' — chacma baboon (''

Papio ursinus The chacma baboon (''Papio ursinus''), also known as the Cape baboon, is, like all other baboons, from the Old World monkey family. It is one of the largest of all monkeys. Located primarily in southern Africa, the chacma baboon has a wide vari ...

'') * ''H. semnopitheci'' — crab eating macque ('' Macaca irus''), Sunda Island leaf monkey ('' Presbytis aygula'') * ''H. taiwanensis'' — Formosan rock macque (''

Macaca cyclopis The Formosan rock macaque (''Macaca cyclopis''), also known as the Formosan rock monkey or Taiwanese macaque, is a macaque endemic to the island of Taiwan, which has also been introduced to Japan. Besides humans, Formosan rock macaques are the on ...

'') * '' H. vassali'' — squirrel (''

Callosciurus flavimanus Pallas's squirrel (''Callosciurus erythraeus''), also known as the red-bellied tree squirrel, is a species of squirrel native to Greater China, India, and Southeast Asia. Description Pallas's squirrel is a medium-sized tree squirrel, with a ...

'')

Parasite species unknown

* Red bellied tree squirrel (''

Callosciurus erythraeus Pallas's squirrel (''Callosciurus erythraeus''), also known as the red-bellied tree squirrel, is a species of squirrel native to Greater China, India, and Southeast Asia. Description Pallas's squirrel is a medium-sized tree squirrel, with a ...

'') * Lesser short nosed fruit bat (''

Cynopterus brachyotis The lesser short-nosed fruit bat (''Cynopterus brachyotis'') is a species of megabat within the family Pteropodidae. It is a small bat that lives in South Asia and Southeast Asia. It weighs between , and measures . It occurs in many types of habi ...

'') * Fruit bat (''

'') * Bare-backed fruit bat ('' Dobsonia moluccense'') *

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

n epauletted fruit bat ('' Epomophorus labiatus'') * Large leafnosed bat ('' Hipposideros armiger terasensis'') * Diadem leaf-nosed bat (''

Hipposideros diadema ''Hipposideros'' is one of the most diverse genera of bats, with more than 70 species. They are collectively called roundleaf bats after the shape of their nasal ornament. It is the type genus of the family Hipposideridae. It is divided into spe ...

'') * White-cheeked gibbon (''

'') *

Formosa Taiwan, officially the Republic of China (ROC), is an island country located in East Asia. The main island of Taiwan, formerly known in the Western political circles, press and literature as Formosa, makes up 99% of the land area of the territorie ...

n macaque (''

'') * Southern pig tailed macaque (''

Macaca nemestrina The southern pig-tailed macaque (''Macaca nemestrina''), also known as the Sundaland pig-tailed macaque and Sunda pig-tailed macaque, is a medium-sized macaque that lives in southern Thailand, Malaysia, and Indonesia. It is known locally as ber ...

'') * Long-winged bat (''

Miniopterus schreibersii The common bent-wing bat (''Miniopterus schreibersii''), also known as the Schreibers's long-fingered bat or Schreibers's bat, is a species of insectivorous bat. They appear to have dispersed from a subtropical origin and distributed throughout ...

'') * Olive baboon ('' Papio anubis'') * Yellow baboon (''

'') * Formosan giant flying squirrel ('' Petaurista grandis'') * Orangutan (''

Pongo pygmaeus The Bornean orangutan (''Pongo pygmaeus'') is a species of orangutan endemic to the island of Borneo. Together with the Sumatran orangutan (''Pongo abelii'') and Tapanuli orangutan (''Pongo tapanuliensis''), it belongs to the only genus of grea ...

'') * Black flying fox (''

Pteropus alecto The black flying fox or black fruit bat (''Pteropus alecto'') is a bat in the family Pteropodidae. It is among the largest bats in the world, but is considerably smaller than the largest species in its genus, ''Pteropus''. The black flying fox ...

'') * Small flying fox (''

Pteropus hypomelanus The small flying fox, island flying fox or variable flying fox (''Pteropus hypomelanus'') is a species of flying fox in the family Pteropodidae. It is found in Australia, Cambodia, Indonesia, Malaysia, the Maldives, Myanmar, Papua New Guinea, t ...

'') * Horseshoe bat ('' Rhinolophus'') species

Vectors

Known vectors belong to the genus '' Culicoides''. Species of '' Streblidae'' may also be able to act as vectors but this is not yet certain. *''H. brayi'' — ''

Culicoides nubeculosus ''Culicoides'' is a genus of biting midges in the family Ceratopogonidae. There are over 1000 species in the genus,Connelly, C. RBiting midges: ''Culicoides'' spp.Featured Creatures, Entomology and Nematology Department, University of Florida IFA ...

'' and ''

Culicoides variipennis ''Culicoides variipennis'' is a long biting midge. It is a part of the subgenus ''Monoculicoides'' and has many subspecies. Found in North America, ''C. variipennis'' transmits Bluetongue virus, African horse sickness virus, akabane virus, and ep ...

'' *''H. kochi'' — ''

Culicoides adersi ''Culicoides'' is a genus of biting midges in the family Ceratopogonidae. There are over 1000 species in the genus,Connelly, C. RBiting midges: ''Culicoides'' spp.Featured Creatures, Entomology and Nematology Department, University of Florida IFA ...

'' Ingram and Macfie 1923 *''H. levinei'' — ''

References

{{Taxonbar, from=Q5731756 Apicomplexa genera Haemosporida