''Hepatocystis'' is a genus of parasites transmitted by midges of the genus ''

Culicoides ''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 IF ...

''. Hosts include Old World primates,

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 ...

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 Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

. 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 epomophori'' * '' Hepatocystis fieldi'' * '' Hepatocystis foylei'' * '' Hepatocystis garnhami'' * '' Hepatocystis hipposideri'' * '' Hepatocystis hippopotami'' * ''

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 limnotragi'' * ''

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 taiwanensis'' * '' Hepatocystis vassali''

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

eosinophil Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...

s and

histiocyte A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyt ...

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, v ...

hemosiderosis Hemosiderosis is a form of iron overload disorder resulting in the accumulation of hemosiderin. Types include: * Transfusion hemosiderosis * Idiopathic pulmonary hemosiderosis * Transfusional diabetes Organs affected: * Hemosiderin deposit ...

with the loss of normal architecture. The cystlike exoerythrocytic

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 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 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 ...

. Within the erythrocytes the merozoites first become ring forms, then

trophozoite A trophozoite (G. ''trope'', nourishment + ''zoon'', animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing ''Plasmodium falciparum'' and those of the ''Giardia'' group. (The complement of the trophozoi ...

s 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 ver ...

'' 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 negative. Haemozoin 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 oocysts 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

s 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'').

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 are ...

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'') * ''H. bouillezi'' — mona monkey ('' Cercopithecus mona'') * ''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 The hammer-headed bat ('), also known as hammer-headed fruit bat and big-lipped bat, is a megabat widely distributed in West and Central Africa. It is the only member of the genus ''Hypsignathus'', which is part of the tribe Epomophorini along w ...

'') * ''H. cercopitheci'' — De Brazza's monkey ('' Cercopithecus neglectus'') 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 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 extant ...

'') * ''H. hipposideri'' — large leafnosed bat ('' Hipposideros armiger terasensis''). * ''H. kochi'' — African green monkeys (''

Cercopithecus aethiops The vervet monkey (''Chlorocebus pygerythrus''), or simply vervet, is an Old World monkey of the family Cercopithecidae native to Africa. The term "vervet" is also used to refer to all the members of the genus ''Chlorocebus''. The five distinct ...

''), 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 genus ...

'') * ''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 ''Pteropus'': the little red '' P. scapulatus'', spectacled '' P. conspicilla ...

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

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

n fruit bat ('' Lissonycteris angolensis''), little collared fruit bat (''

Myonycteris torquata ''Myonycteris'' (collared bat) is a genus of bat in the family Pteropodidae. It contains the following species:Simmons, 2005, p. 328 Genus ''Myonycteris'' * São Tomé collared fruit bat, ''Myonycteris brachycephala'' * East African little ...

''), * ''H. pteropi'' — bat ('' Cynopterus bracyotis''), Horsefield's fruit bat ('' Cynopterus horsfieldi''), bat ('' Pteropus colinus''), common flying fox ('' Pteropus edwarsii''), spectacled flying fox ('' Pteropus conspicillatus''), fruit bat ('' Pteropus geddiei''), black flying fox ('' Pteropus gouldi''), grey-headed flying fox (''

''), little red flying fox ('' Pteropus sacpulatus'') * ''H. rhodiani'' — bat ('' Hipposideros galeritus'') * ''H. simiae'' — chacma baboon ('' Papio ursinus'') * ''H. semnopitheci'' — crab eating macque (''

Macaca irus The crab-eating macaque (''Macaca fascicularis''), also known as the long-tailed macaque and referred to as the cynomolgus monkey in laboratories, is a cercopithecine primate native to Southeast Asia. A species of macaque, the crab-eating macaque ...

''), Sunda Island leaf monkey ('' Presbytis aygula'') * ''H. taiwanensis'' — Formosan rock macque ('' Macaca cyclopis'') * '' H. vassali'' — squirrel ('' Callosciurus flavimanus'')

Parasite species unknown

* Red bellied tree squirrel ('' Callosciurus erythraeus'') * 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 ('' Cynopterus horsfieldi'') * 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 s ...

'') * White-cheeked gibbon (''

'') * Formosan macaque ('' Macaca cyclopis'') * 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'') * Olive baboon (''

Papio anubis The olive baboon (''Papio anubis''), also called the Anubis baboon, is a member of the family Cercopithecidae Old World monkeys. The species is the most wide-ranging of all baboons, being native to 25 countries throughout Africa, extending fro ...

'') * Yellow baboon ('' Papio cynocephalus'') * Formosan giant flying squirrel ('' Petaurista grandis'') * Orangutan ('' Pongo pygmaeus'') * 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'') * Horseshoe bat ('' Rhinolophus'') species

Vectors

Known vectors belong to the genus ''

''. Species of ''

Streblidae The Streblidae are a family of flies in the superfamily Hippoboscoidea, and together with their relatives the Nycteribiidae, are known as bat flies. They are winged or wingless ectoparasites of bats, and often have long legs. They appear to be ...

'' may also be able to act as vectors but this is not yet certain. *''H. brayi'' — '' Culicoides nubeculosus'' 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'' Ingram and Macfie 1923 *''H. levinei'' — '' Culicoides nubeculosus''

References

{{Taxonbar, from=Q5731756 Apicomplexa genera Haemosporida