Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differentl ...
of
trematodes
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host ...
in the
Platyhelminthes
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a Phylum (biology), phylum of relati ...
phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature f ...
, consisting of
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...
s (known as ''flukes'') with a
syncytial
A syncytium (; plural syncytia; from Greek: σύν ''syn'' "together" and κύτος ''kytos'' "box, i.e. cell") or symplasm is a multinucleate cell which can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus) ...
tegument and, usually, two
suckers, one ventral and one oral. Adults commonly live within the digestive tract, but occur throughout the organ systems of all classes of
vertebrates
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, ...
. Once thought to be related to the
Monogenea
Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female repro ...
, it is now recognised that they are closest to the
Aspidogastrea
The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of Trematoda, flukes comprising about 80 species. It is a Subclass (biology), subclass of the Trematode, trematoda, and sister group to the Digenea. Specie ...
and that the Monogenea are more closely allied with the
Cestoda
Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
. Around 6,000 species have been described to date.
Morphology
Key features
Characteristic features of the Digenea include a syncytial tegument; that is, a tegument where the junctions between cells are broken down and a single continuous cytoplasm surrounds the entire animal. A similar tegument is found in other members of the
Neodermata
Neodermata is a clade of rhabditophoran flatworms containing the parasitic groups Trematoda, Monogenea and Cestoda.
Description
All neodermatans are parasites, in many groups having a free-swimming larval stage. The most striking feature unit ...
; a group of
platyhelminths
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...
comprising the Digenea,
Aspidogastrea
The Aspidogastrea (Ancient Greek: ' “shield”, ' “stomach/pouch”) is a small group of Trematoda, flukes comprising about 80 species. It is a Subclass (biology), subclass of the Trematode, trematoda, and sister group to the Digenea. Specie ...
,
Monogenea
Monogeneans are a group of ectoparasitic flatworms commonly found on the skin, gills, or fins of fish. They have a direct lifecycle and do not require an intermediate host. Adults are hermaphrodites, meaning they have both male and female repro ...
and
Cestoda
Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of man ...
. Digeneans possess a
vermiform
Vermiform (ˈvərməˌfôrm) describes something shaped like a worm. The expression is often employed in biology and anatomy to describe usually soft body parts or animals that are more or less tubular or cylindrical. The word root is Latin, ''ve ...
, unsegmented body-plan and have a solid
parenchyma with no
body cavity
A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid.
The two largest human body cavities are the ventral body cavity, and ...
(
coelom) as in all platyhelminths.
![Peerj-292-fig-7 Zoogonidae](https://upload.wikimedia.org/wikipedia/commons/9/95/Peerj-292-fig-7_Zoogonidae.png)
There are typically two
sucker
Sucker may refer to:
General use
* Lollipop or sucker, a type of confection
* Sucker (slang), a slang term for a very gullible person
* Hard candy
** Cough drop
** Mint (candy)
Biology
* Sucker (botany), a term for a shoot that arises undergro ...
s, an
anterior oral
The word oral may refer to:
Relating to the mouth
* Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid
**Oral administration of medicines
** Oral examination (also known as an oral exam or or ...
sucker surrounding the
mouth, and a
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
sucker sometimes termed the
acetabulum, on the ventral surface. The oral sucker surrounds the mouth, while the ventral sucker is a blind muscular organ with no connection to any internal structure.
A ''monostome'' is a worm with one sucker (oral).
Flukes with an oral sucker and an acetabulum at the posterior end of the body are called ''Amphistomes''. ''Distomes'' are flukes with an oral sucker and a ventral sucker, but the ventral sucker is somewhere other than posterior. These terms are common in older literature, when they were thought to reflect systematic relationships within the groups. They have fallen out of use in modern digenean taxonomy.
Reproductive system
The vast majority of digeneans are
hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
s. This is likely to be an adaptation to low abundance within hosts, allowing the life cycle to continue when only one individual successfully infects the final host.
Fertilisation is internal, with
sperm
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...
being transferred via the
cirrus
Cirrus may refer to:
Science
*Cirrus (biology), any of various thin, thread-like structures on the body of an animal
*Cirrus (botany), a tendril
* Infrared cirrus, in astronomy, filamentary structures seen in infrared light
*Cirrus cloud, a typ ...
to the
Laurer's Canal or
genital aperture
A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...
. A key group of digeneans which are
dioecious
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...
are the
schistosomes
''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed ''schistosomiasis'', which is considered by the World Health Organi ...
.
Asexual reproduction in the first larval stage is ubiquitous.
While the sexual formation of the digenean
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
and asexual reproduction in the first
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
l stage (miracidium) is widely reported, the
developmental biology
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and di ...
of the asexual stages remains a problem.
Electron microscopic studies have shown that the
light microscopically visible germ balls consist of
mitotically
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...
dividing
cell
Cell most often refers to:
* Cell (biology), the functional basic unit of life
Cell may also refer to:
Locations
* Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...
s which give rise to
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
s and to a line of new
germ cells
Germ or germs may refer to:
Science
* Germ (microorganism), an informal word for a pathogen
* Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually
* Germ layer, a primary layer of cells that forms during embryo ...
that become included in these embryonic stages. Since the absence of
meiotic processes is not proven, the exact definition remains doubtful.
Male organs
Protandry
Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...
is the general rule among the Digenea. Usually two
testes
A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...
are present, but some flukes can have more than 100. Also present are
vasa efferentia
The efferent ducts (or efferent ductules or ductuli efferentes or ductus efferentes or vasa efferentia) connect the rete testis with the initial section of the epididymis.Hess 2018
There are two basic designs for efferent ductule structure:
* ...
, a
vas deferens
The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube ...
,
seminal vesicle
The seminal vesicles (also called vesicular glands, or seminal glands) are a pair of two convoluted tubular glands that lie behind the urinary bladder of some male mammals. They secrete fluid that partly composes the semen.
The vesicles are 5 ...
,
ejaculatory duct
The ejaculatory ducts (''ductus ejaculatorii'') are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the ureth ...
and a cirrus (analogous to a penis) usually (but not always) enclosed in a cirrus sac. The cirrus may or may not be covered in proteinaceous spines. The exact conformation of these organs within the male terminal genitalia is taxonomically important at the familial and generic levels.
Female organs
Usually there is a single
ovary
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...
with an
oviduct
The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, o ...
, a
seminal receptacle
Female sperm storage is a biological process and often a type of sexual selection in which sperm cells transferred to a female during mating are temporarily retained within a specific part of the reproductive tract before the oocyte, or egg, is f ...
, a pair of vitelline glands (involved in
yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example ...
and egg-shell production) with ducts, the ootype (a chamber where eggs are formed), a complex collection of glands cells called ''Mehlis’ gland'', which is believed to lubricate the uterus for egg passage.
In addition, some digeneans possess a canal called
Laurer's Canal, which leads from the oviduct to the dorsal surface of the body. The function of this canal is debated, but it may be used for insemination in some species or for disposal of waste products from reproduction in other species.
Most trematodes possess an ovicapt, an enlarged portion of the oviduct where it joins the ovary. It probably controls the release of ova and spaces out their descent down the uterus.
The uterus typically opens into a common genital atrium that also received the distal male copulatory organ (cirrus) before immediately opening onto the outer surface of the worm. The distal part of the uterus may be expanded into a metraterm, set off from the proximal uterus by a muscular sphincter, or it may be lined with spines, as in the
Monorchiidae
Monorchiidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few sig ...
and some other families.
Digestive system
As adults, most digeneans possess a terminal or subterminal mouth, a muscular pharynx that provides the force for ingesting food, and a forked, blind digestive system consisting of two tubular sacs called caeca (sing.
caecum
The cecum or caecum is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix, to which it is joined). The wo ...
). In some species the two gut caeca join posteriorly to make a ring-shaped gut or
cyclocoel. In others the
caeca may fuse with the body wall posteriorly to make one or more
anuses, or with the excretory vesicle to form a
uroproct. Digeneans are also capable of direct nutrient uptake through the tegument by
pinocytosis
In cellular biology, pinocytosis, otherwise known as fluid endocytosis and bulk-phase pinocytosis, is a mode of endocytosis in which small molecules dissolved in extracellular fluid are brought into the cell through an invagination of the cell ...
and
phagocytosis
Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is ...
by the
syncitium. Most adult digeneans occur in the vertebrate
alimentary canal or its associated
organs
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...
, where they most often graze on contents of the lumen (e.g., food ingested by the host, bile, mucus), but they may also feed across the mucosal wall (e.g.,
submucosa, host blood). The blood flukes, such as schistosomes, spirorchiids and sanguinicolids, feed exclusively on blood. Asexual stages in
mollusc intermediate hosts feed mostly by direct absorption, although the
redia stage found in some groups does have a mouth, pharynx and simple gut and may actively consume host tissue or even other parasites. Encysted
metacercarial stages and free-living
cercaria
A cercaria (plural cercariae) is the larval form of the trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in w ...
l stages do not feed.
Nervous system
Paired
ganglia at the anterior end of the body serve as the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
. From this
nerves
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system.
A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...
extend anteriorly and posteriorly.
Sensory receptors
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell ...
are, for the most part, lacking among the adults, although they do have
tangoreceptor cells. Larval stages have many kinds of sensory receptors, including light receptors and chemoreceptors. Chemoreception plays an important role in the free-living miracidial larva recognising and locating its host.
Life cycles
There is a bewildering array of variation on the complex digenean life cycle, and plasticity in this trait is probably a key to the group's success. In general, the life cycles may have two, three, or four obligate (necessary) hosts, sometimes with transport or
paratenic
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' ( symbiont). The guest is typically provided with nourishment and shelter. Examples include ...
hosts in between. The three-host life cycle is probably the most common. In almost all species, the first host in the life cycle is a
mollusc.
This has led to the inference that the ancestral digenean was a mollusc parasite and that vertebrate hosts were added subsequently.
The alternation of sexual and asexual generations is an important feature of digeneans. This phenomenon involves the presence of several discrete generations in one life-cycle.
A typical digenean trematode life cycle is as follows. Eggs leave the
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, ...
host in
faeces
Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
and use various strategies to infect the first
intermediate host
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...
, in which sexual reproduction does not occur. Digeneans may infect the first intermediate host (usually a
snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
) by either passive or active means. The eggs of some digeneans, for example, are (passively) eaten by snails (or, rarely, by an
annelid
The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...
worm),
in which they proceed to hatch. Alternatively, eggs may hatch in water to release an actively swimming, ciliated larva, the
miracidium
The Miracidium is the second stage in the life cycle of trematodes. When trematode eggs are laid and come into contact with fresh water, they hatch and release miracidium. In this phase, miracidia are ciliated and free-swimming. This stage is com ...
, which must locate and penetrate the body wall of the snail host.
After post-ingestion hatching or penetration of the snail, the miracidium metamorphoses into a simple, sac-like ''mother sporocyst''. The mother sporocyst undergoes a round of internal
asexual reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the fu ...
, giving rise to either ''rediae'' (sing. redia) or ''daughter sporocysts''. The second generation is thus the daughter parthenita sequence. These in turn undergo further asexual reproduction, ultimately yielding large numbers of the second free-living stage, the ''cercaria'' (pl. cercariae).
Free-swimming cercariae leave the snail host and move through the aquatic or
marine environment, often using a whip-like tail, though a tremendous diversity of tail morphology is seen. Cercariae are infective to the second host in the life cycle, and infection may occur passively (e.g., a
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
consumes a cercaria) or actively (the cercaria penetrates the fish).
The life cycles of some digeneans include only two hosts, the second being a vertebrate. In these groups, sexual maturity occurs after the cercaria penetrates the second host, which is in this case also the
definitive host
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' ( symbiont). The guest is typically provided with nourishment and shelter. Examples include ...
. Two-host life cycles can be primary (there never was a third host) as in the
Bivesiculidae, or secondary (there was at one time in evolutionary history a third host but it has been lost).
In three-host life cycles, cercariae develop in the second intermediate host into a resting stage, the ''metacercaria'', which is usually encysted in a
cyst
A cyst is a closed sac, having a distinct envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac (like the manner in which ...
of host and parasite origin, or encapsulated in a layer of tissue derived from the host only. This stage is infective to the
definitive host
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' ( symbiont). The guest is typically provided with nourishment and shelter. Examples include ...
. Transmission occurs when the definitive host preys upon an infected second intermediate host. Metacercariae excyst in the definitive host's gut in response to a variety of physical and chemical signals, such as gut
pH levels, digestive
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s,
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
, etc. Once excysted, adult digeneans migrate to more or less specific sites in the definitive host and the life cycle repeats.
Evolution
The evolutionary origins of the Digenea have been debated for some time, but there appears general agreement that the proto-digenean was a parasite of a mollusc, possibly of the mantle cavity. Evidence for this comes from the ubiquity of molluscs as first intermediate hosts for digeneans, and the fact that most aspidogastreans (the sister group to the Digenea) also have mollusc associations. It is thought that the early trematodes (the collective name for digeneans and aspidogastreans) likely evolved from rhabdocoel
turbellaria
The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes (flatworms), and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to large freshwater forms more ...
ns that colonised the open mantle cavity of early molluscs.
It is likely that more complex life cycles evolved through a process of terminal addition, whereby digeneans survived predation of their mollusc host, probably by a fish. Other hosts were added by the same process until the modern bewildering diversity of life cycle patterns developed.
Important families
Digenea includes about 80 families.
[Olson P. D., Cribb T. H., Tkach V. V., Bray R. A. & Littlewood D. T. J. (2003). "Phylogeny and classification of the Digenea (Platyhelminthes: Trematoda)". ''International Journal for Parasitology'' 33(7): 733–755. ] They are listed below, organised by order.
Digenea
*
Diplostomida
Diplostomida is an order of trematodes in the subclass Digenea. It is synonymous with Strigeida Poche, 1926.
Families
Order Diplostomida
*Suborder Diplostomata
**Superfamily Brachylaimoidea Joyeux & Foley, 1930
***Brachylaimidae Joyeux & Foley, ...
**Suborder Diplostomata
***Superfamily Brachylaimoidea
Joyeux & Foley, 1930
****
Brachylaimidae
Brachylaimidae is a family of parasitic flukes in the sub-class Digenea. Adults are usually found within the digestive tracts and other organs of mammals or birds and have a complex three-stage life cycle.Olson, P. D.; Cribb, T. H.; Tkach, V. V. ...
Joyeux & Foley, 1930
****
Leucochloridiidae
''Leucochloridium'' is a genus of parasitic trematode worms in the order Diplostomida. It Is the sole genus in the family Leucochloridiidae.Carus, C. G. (1835). Beobachtung über einen merkwürdigen schöngefärbten Eingeweidewurm, ''Leucochlorid ...
Poche, 1907
***Superfamily Diplostomoidea
Poirier, 1886
****
Brauninidae
Brauninidae is a monotypic family of trematodes in the order Diplostomida. It consists of one genus, ''Braunina'' Heider, 1900,Heider, K. (1900). Über ''Braunina'', ein neues Genus aus der Gruppe der Hemistomidae. ''Verhandlungen der Deutschen Z ...
Wolf, 1903
****
Cyathocotylidae
Cyathocotylidae is a family of trematodes in the order Diplostomida
Diplostomida is an order of trematodes in the subclass Digenea. It is synonymous with Strigeida Poche, 1926.
Families
Order Diplostomida
*Suborder Diplostomata
**Superfamily ...
Mühling, 1898
****
Diplostomidae
Diplostomidae is a family of trematodes in the order Diplostomida.
Genera
*'' Austrodiplostomum'' Szidat & Nani, 1951Szidat, L. & Nani, A. (1951). Diplostomiasis cerebralis del Pejerrey. Una grave epizootia que afecta a la economia nacional prod ...
Poirier, 1886
****
Proterodiplostomidae
Proterodiplostomidae is a monotypic family of trematodes in the order Diplostomida. It consists of one subfamily, Polycotylinae Monticelli, 1888,Monticelli, F. S. (1888). ''Saggio di una morfologia del trematodi. Tesi per ottenere la privata doce ...
Dubois, 1936
****
Strigeidae
Strigeidae is a family of trematodes in the order Diplostomida.
Genera
*''Apatemon'' Szidat, 1928Szidat, L. (1928). Zur Revision der Trematodengattung ''Strigea'' Abildgaard. ''Centralblatt für Bakteriologie, Parasitenkunde und Infektionskrankh ...
Railliet, 1919
***Superfamily Schistosomatoidea
Stiles & Hassall, 1898
****
Aporocotylidae
Aporocotylidae is a family of trematodes within the order Diplostomida, which contains species commonly known as fish blood flukes. It contains more than 40 genera, the largest being '' Cardicola''. Species in this family parasite fish in both ...
Odhner, 1912
****
Schistosomatidae
Schistosomatidae is a family of digenetic trematodes with complex parasitic life cycles. Immature developmental stages of schistosomes are found in molluscs and adults occur in vertebrates. The best studied group, the blood flukes of the genus ...
Stiles & Hassall, 1898
****
Spirorchiidae
Spirorchiidae is a family of digenetic trematodes. Infestation by these trematodes leads to the disease spirorchiidiosis. Spirorchiids are mainly parasites of turtles. It has been synonymised with Proparorchiidae Ward, 1921, Spirorchidae Stunka ...
Stunkard, 1921
*
Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few significant parasites of humans.
The following families are placed here, organ ...
**Apocreadiata
***Apocreadioidea
Skrjabin, 1942
****
Apocreadiidae
Apocreadiidae is a family of parasitic worms in the class Trematoda
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in ...
Skrjabin, 1942
**Bivesiculata
***Bivesiculoidea
****
Bivesiculidae Yamaguti, 1934
**Bucephalata
***Bucephaloidea
Poche, 1907
****
Bucephalidae
Bucephalidae is a family of trematodes that parasitize fish. They lack suckers, having instead a muscular organ called a "rhynchus" at the front end which they use to attach to their hosts. The characteristics of the rhynchus are used to help def ...
Poche, 1907
****
Nuitrematidae Kurochkin, 1975
***Gymnophalloidea
Odhner, 1905
****
Botulisaccidae
Botulisaccidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Yamaguti, 1971
****
Fellodistomidae
Fellodistomidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively fe ...
Nicoll, 1909
****
Gymnophallidae Odhner, 1905
****
Tandanicolidae
Tandanicolidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Johnston, 1927
**Echinostomata
***Echinostomatoidea
Looss, 1902
****
Calycodidae Dollfus, 1929
****
Cyclocoelidae Stossich, 1902
****
Echinochasmidae
Echinochasmidae is a family of trematodes in the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few signific ...
Odhner, 1910
****
Echinostomatidae
Echinostomatidae is a Family (biology), family of Trematoda, trematodes in the Order (biology), order Plagiorchiida, first described in 1899.Fuhrmann, O. (1928). ''Zweite Klasse des Cladus Platyhelminthes: Trematoda''. Berlin & Leipzig: Kükentha ...
Looss, 1899
****
Eucotylidae
Eucotylidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few sig ...
Cohn, 1904
****
Fasciolidae Railliet, 1895
****
Himasthlidae Odhner, 1910
****
Philophthalmidae
Philophthalmidae is a family of trematodes in the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few signific ...
Looss, 1899
****
Psilostomidae Looss, 1900
****
Rhytidodidae Odhner, 1926
****
Typhlocoelidae Harrah, 1922
**Haplosplanchnata
***Haplosplanchnoidea
Poche, 1925
****
Haplosplanchnidae
Haplosplanchnidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively fe ...
Poche, 1926
**Hemiurata
***Azygioidea
Lühe, 1909
****
Azygiidae Lühe, 1909
***Hemiuroidea
Looss, 1899
****
Accacoeliidae Odhner, 1911
****
Bathycotylidae Dollfus, 1932
****
Derogenidae Nicoll, 1910
****
Dictysarcidae
Dictysarcidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Aerobiotrema'' Yamaguti, 1958
* ''Albulatrema'' Yamaguti, 1965
* ''Cylindrorchis'' Southwell, 1913
* ''Dictysarca'' Linton, 1910
* ''Elongoparorchis'' Rao, ...
Skrjabin & Guschanskaja, 1955
****
Didymozoidae
Didymozoidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few sig ...
Monticelli, 1888
****
Gonocercidae
Gonocercidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few s ...
Skrjabin & Guschanskaja, 1955
****
Hemiuridae
Hemiuridae is a family of trematodes belonging to the order Plagiorchiida containing 514 described species.
Genera
Genera:
* ''Adinosoma'' Manter, 1947
* ''Allostomachicola'' Yamaguti, 1958
* ''Aphanuroides'' Nagaty & Abdel-Aal, 1962
* ''Aphan ...
Looss, 1899
****
Hirudinellidae Dollfus, 1932
****
Isoparorchiidae Travassos, 1922
****
Lecithasteridae Odhner, 1905
****
Ptychogonimidae
Ptychogonimidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Melogonimus'' Bray, Brockerhoff & Cribb, 1995
* ''Ptychogonimus'' Lühe, 1900
References
Plagiorchiida
Trematode families
{{Trematoda-stub ...
Dollfus, 1937
****
Sclerodistomidae
Sclerodistomidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Eurycoelum'' Brock, 1886
* ''Kenmackenzia'' Gibson, 1983
* ''Prosogonotrema'' Vigueras, 1940
* ''Prosorchiopsis'' Robert-Philippe Dollfus, Dollfus, 1947
...
Odhner, 1927
****
Sclerodistomoididae Gibson & Bray, 1979
****
Syncoeliidae Looss, 1899
**Heronimata
***Heronimoidea
Ward, 1918
****
Heronimidae
Heronimidae is a family of digenean trematode parasites consisting of a single genus with a single species.Pearson, J. C. (1992). On the position of the digenean family Heronimidae: an inquiry into a cladistic classification of the Digenea. ''Sys ...
Ward, 1918
**Lepocreadiata
***Lepocreadioidea
Odhner, 1905
****
Aephnidiogenidae
Aephnidiogenidae is a Family (biology), family of Trematoda, trematodes in the Order (biology), order Plagiorchiida.
Genera
*''Aephnidiogenes'' Nicoll, 1915Nicoll, W. (1915). The trematode parasites of north Queensland. III. Parasites of fishes. ...
Yamaguti, 1934
****
Deropristidae Cable & Hunninen, 1942
****
Enenteridae Yamaguti, 1958
****
Gorgocephalidae
Gorgocephalidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Gorgocephalus'' Manter, 1966
References
Plagiorchiida
Trematode families
{{Trematoda-stub ...
Manter, 1966
****
Gyliauchenidae
Gyliauchenidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Fukui, 1929
****
Lepidapedidae
Lepidapedidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few s ...
Yamaguti, 1958
****
Lepocreadiidae
Lepocreadiidae is a family of trematodes in the order Plagiorchiida.WoRMS (2018). Lepocreadiidae Odhner, 1905. Accessed at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=108438 on 2018-10-17
Genera
According to the World Register of Mar ...
Odhner, 1905
****
Liliatrematidae Gubanov, 1953
**Monorchiata
***Monorchioidea
Odhner, 1911
****
Lissorchiidae
Lissorchiidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few si ...
Magath, 1917
****
Monorchiidae
Monorchiidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few sig ...
Odhner, 1911
**Opisthorchiata
***Opisthorchioidea
Braun, 1901
****
Cryptogonimidae
Cryptogonimidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Ward, 1917
****
Heterophyidae
Heterophyidae is a family of intestinal trematodes in the order Plagiorchiida.
Description: " Tegument covered by spines. Oral sucker not armed or armed by cyrcumoral spines. Pharynx presented. Genital synus presented. Ventral and genital suc ...
Leiper, 1909
****
Opisthorchiidae
Opisthorchiidae is a family of digenean trematodes. Opisthorchiidae have cosmopolitan distribution.
The most medically important species in the family Opisthorchiidae are ''Clonorchis sinensis'', ''Opisthorchis viverrini'', and '' Opisthorchis ...
Looss, 1899
**Pronocephalata
***Paramphistomoidea
Fischoeder, 1901
****
Cladorchiidae Fischoeder, 1901
****
Mesometridae
Mesometridae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few si ...
Poche, 1926
****
Microscaphidiidae
Microscaphidiidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively fe ...
Looss, 1900
****
Paramphistomidae
Paramphistomidae is a Family (biology), family of Trematoda, trematodes in the Order (biology), order Plagiorchiida.
Classification
This family contains two subfamilies consisting of 17 genera.Jones, A., Bray, R. A., & Gibson, D. I. (Eds.). (20 ...
Fischoeder, 1901
***Pronocephaloidea
Looss, 1899
****
Labicolidae
Labicolidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few sig ...
Blair, 1979
****
Notocotylidae Lühe, 1909
****
Nudacotylidae Barker, 1916
****
Opisthotrematidae Poche, 1926
****
Pronocephalidae Looss, 1899
****
Rhabdiopoeidae
Rhabdiopoeidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Poche, 1926
**Transversotremata
***Transversotrematoidea
Witenberg, 1944
****
Transversotrematidae Witenberg, 1944
**Xiphidiata
***Allocreadioidea
Looss, 1902
****
Acanthocolpidae Lühe, 1906
****
Allocreadiidae
Allocreadiidae is a family of flatworms belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few s ...
Looss, 1902
****
Batrachotrematidae
Batrachotrematidae is a family of trematodes in the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few signi ...
Dollfus & Williams, 1966
****
Brachycladiidae
Brachycladiidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Odhner, 1905
****
Opecoelidae
Opecoelidae is a family of trematodes. It is the largest digenean family with over 90 genera and nearly 900 species, almost solely found in marine and freshwater teleost fishes.Bray, Rodney A., Cribb, Thomas H., Littlewood, D. Timothy J. & Waesch ...
Ozaki, 1925
***Gorgoderoidea
Looss, 1901
****
Callodistomidae Odhner, 1910
****
Dicrocoeliidae
Dicrocoeliidae is a family of flatworms belonging to the order Plagiorchiida.
Genera
Genera:
* '' Allocorrigia'' Turner & Corkum, 1977
* '' Athesmia'' Looss, 1899
* '' Brachydistomum '' , 1944
* '' Brachylecithum'' Shtrom, 1940
* '' Brodenia'' Ge ...
Looss, 1899
****
Gorgoderidae
Gorgoderidae is a Family (biology), family of Trematoda, trematodes in the Order (biology), order Plagiorchiida.
Genera
Family Gorgoderidae
*Subfamily Anporrhutinae Looss, 1901
**''Anaporrhutum'' Brandes in Ofenheim, 1900
**''Bicornuata'' Pearse ...
Looss, 1899
***Haploporoidea
Nicoll, 1914
****
Atractotrematidae
Atractotrematidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively f ...
Yamaguti, 1939
****
Haploporidae
Haploporidae is a family (biology), family of Trematoda, trematodes in the Order (biology), order Plagiorchiida.
Genera
The genera are organised by their subfamily.
*Chalcinotrematinae Overstreet & Curran, 2005
**''Chalicinotrema'' Texeira de Fr ...
Nicoll, 1914
***Microphalloidea
Ward, 1901
****
Diplangidae Yamaguti, 1971
****
Exotidendriidae
Exotidendriidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Mehra, 1935
****
Faustulidae Poche, 1926
****
Microphallidae
''Microphallidae'' is a family of trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction ...
Ward, 1901
****
Pachypsolidae
Pachypsolidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few s ...
Yamaguti, 1958
****
Phaneropsolidae
Phaneropsolidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Microtrema'' Sitko, 2013
* ''Mosesia'' Travassos, 1928
References
Plagiorchiida
Trematode families
{{trematoda-stub ...
Mehra, 1935
****
Pleurogenidae
Pleurogenidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Cortrema'' Tang, 1951
* ''Langeronia'' Caballero & Bravo-Hollis, 1949
* ''Nenimandijea'' Kaw, 1950
* ''Pleurogenes'' Looss, 1896
* ''Pleurogenoides'' Travas ...
Looss, 1899
****
Prosthogonimidae
The Prosthogonimidae are a family of trematodes. They are part of the huge of the suborder Xiphidiata in the order Plagiorchiida. The adults of these parasites occur in the bursa of Fabricius, caecum, cloaca, liver, oviduct and sometimes even ...
Lühe, 1909
****
Renicolidae Dollfus, 1939
****
Zoogonidae
Zoogonidae are a family of trematodes. They are the namesake family of the suborder Zoogonata in the order Plagiorchiida.
Selected genera are:
* ''Brevicreadium''
* ''Deretrema'' Linton, 1910
* ''Diphtherostomum'' Stossich, 1904
* ''Glauciv ...
Odhner, 1902
***Plagiorchioidea
Lühe, 1901
****
Auridistomidae Lühe, 1901
****
Brachycoeliidae
Brachycoeliidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Brachycoelium'' Dujardin, 1845
* ''Brachycoelium'' Stiles & Hassall, 1898
* ''Cymatocarpus (flatworm), Cymatocarpus'' Looss, 1899
* ''Parabrachycoelium'' ...
Looss, 1899
****
Cephalogonimidae Looss, 1899
****
Choanocotylidae
Choanocotylidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Jue Sue & Platt, 1998
****
Echinoporidae
Echinoporidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few s ...
Krasnolobova & Timofeeva, 1965
****
Encyclometridae Mehra, 1931
****
Leptophallidae
Leptophallidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few ...
Dayal, 1938
****
Macroderoididae McMullen, 1937
****
Meristocotylidae
Meristocotylidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Meristocotyle'' Fischthal & Kuntz, 1964
References
Plagiorchiida
{{Trematoda-stub ...
Fischthal & Kuntz, 1981
****
Ocadiatrematidae
Ocadiatrematidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively f ...
Fischthal & Kuntz, 1981
****
Orientocreadiidae
Orientocreadiidae is a family of trematodes belonging to the order Plagiorchiida.
Genera:
* ''Macrotrema
''Macrotrema caligans'' is a species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic r ...
Yamaguti, 1958
****
Plagiorchiidae Lühe, 1901
****
Styphlotrematidae
Styphlotrematidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively f ...
Baer, 1924
****
Telorchiidae
Telorchiidae is a family of trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occ ...
Looss, 1899
****
Thrinascotrematidae
Thrinascotrematidae is a family of trematodes belonging to the order Plagiorchiida
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively ...
Jue Sue & Platt, 1999
****
Urotrematidae Poche, 1926
Human digenean infections
Only about 12 of the 6,000 known species are
infectious
An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
to humans, but some of these species are important
disease
A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
s afflicting over 200 million people. The species that infect humans can be divided into groups, the schistosomes and the non-schistosomes.
Schistosomes
The Schistosomes occur in the
circulatory system
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
of the definitive host. Humans become infected after free-swimming cercaria liberated from infected snails penetrate the skin. These dioecious worms are long and thin, ranging in size from 10 to 30 mm in length to 0.2 to 1.0 mm in diameter. Adult males are shorter and thicker than females, and have a long groove along one side of the body in which the female is clasped. Females reach sexual maturity after they have been united with a male. After mating the two remain locked together for the rest of their lives. They can live for several years and produce many thousands of eggs.
The four species of schistosomes that infect humans are members of the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Schistosoma
''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed '' schistosomiasis'', which is considered by the World Health Organ ...
''.
Non-schistosomes
The seven major species of non-schistosomes that infect humans are listed below. People become infected after ingesting metacercarial cysts on plants or in undercooked animal flesh. Most species inhabit the human gastrointestinal tract, where they shed eggs along with host feces. ''Paragonimus westermani'', which colonizes the lungs, can also pass its eggs in
saliva
Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be ...
. These flukes generally cause mild pathology in humans, but more serious effects may also occur.
References
Notes
* Gibson, D.I., Jones, A. & Bray, R.A. (2002). ''Key to the Trematoda, vol.1''
* Littlewood D.T.J. & Bray R.A. (2001) ''Interrelationships of the Platyhelminthes.''
*
Yamaguti, S. (1971). ''Synopsis of digenetic trematodes of vertebrates.'' Keigaku Publishing Co., Tokyo.
External links
Cambridge University Schistosome Research GroupFishdisease.net
{{Taxonbar, from=Q132650
Protostome subclasses