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Trematoda
Trematoda is a Class (biology), class of flatworms known as flukes. They are obligate parasite, obligate internal Parasitism, parasites with a complex biological life cycle, life cycle requiring at least two Host_(biology), hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five traditional vertebrate classes: mammals, birds, amphibians, reptiles, and fish. Etymology Trematodes are commonly referred to as flukes. This term can be traced back to the Old English name for flounder, and refers to the flattened, rhomboidal shape of the organisms. Taxonomy There are 18,000 to 24,000 known species of trematodes, divided into two subclasses — the Aspidogastrea and the Digenea. Aspidogastrea is the smaller subclass, comprising 61 species. These flukes mainly infect Bivalvia, bivalves and Osteichthyes, bony fishes.https://www.bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organ (anatomy), organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been prove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Species range in length from approximately one millimeter to several centimeters. They are parasites of freshwater and ocean, marine molluscs and vertebrates (Chondrichthyes, cartilaginous and Actinopterygii, bony fishes and turtles). Maturation may occur in the mollusc or vertebrate host. None of the species has any economic importance, but the group is of very great interest to biologists because it has several characters which appear to be archaic. Morphology Shared characteristics Shared characteristics of the group are a large ventral disc with a large number of small Pulmonary alveolus, alveoli ("suckerlets") or a row of suckers and a Tegument (Helminth), tegument with short protrusions, so-called "microtubercles". Larval physiology Larv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digenea
Digenea (Gr. ''Dis'' – double, ''Genos'' – race) is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms (known as ''flukes'') with a syncytial 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. Once thought to be related to the Monogenea, it is now recognised that they are closest to the Aspidogastrea and that the Monogenea are more closely allied with the Cestoda. 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; a group of platyhelminths comprising the Digenea, Aspidogastrea, Monogenea and Cestoda. Digeneans possess a vermifo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Organization as the second-most socioeconomically devastating parasitic disease (after malaria), with hundreds of millions infected worldwide. Adult flatworms parasitize blood capillaries of either the mesenteries or plexus of the bladder, depending on the infecting species. They are unique among trematodes and any other flatworms in that they are dioecious with distinct sexual dimorphism between male and female. Thousands of eggs are released and reach either the bladder or the intestine (according to the infecting species), and these are then excreted in urine or feces to fresh water. Larvae must then pass through an intermediate snail host, before the next larval stage of the parasite emerges that can infect a new mammalian host by directl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schistosoma Mansoni
A paired couple of ''Schistosoma mansoni''. ''Schistosoma mansoni'' is a water-borne parasite of humans, and belongs to the group of blood flukes (''Schistosoma''). The adult lives in the blood vessels ( mesenteric veins) near the human intestine. It causes intestinal schistosomiasis (similar to '' S. japonicum'', '' S. mekongi'', ''S. guineensis'', and '' S. intercalatum''). Clinical symptoms are caused by the eggs. As the leading cause of schistosomiasis in the world, it is the most prevalent parasite in humans. It is classified as a neglected tropical disease. As of 2021, the World Health Organization reports that 236.6 million people have schistosomiasis and most of it is due to ''S. mansoni''. It is found in Africa, the Middle East, the Caribbean, Brazil, Venezuela and Suriname. Unlike other flukes (trematodes) in which sexes are not separate ( monoecious), schistosomes are unique in that adults are divided into males and females, thus, gonochoric. However, a permanent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trichobilharzia Regenti
''Trichobilharzia regenti'' is a neuropathogenic parasitic flatworm of birds which also causes cercarial dermatitis in humans. The species was originally described in 1998 in the Czech Republic and afterwards it was detected also in other European countries, e.g. Denmark, Germany, France, Iceland, Poland, Switzerland, or Russia, and even in Iran. For its unique neurotropic behaviour in vertebrate hosts, the host-parasite interactions are extensively studied in terms of molecular biology, biochemistry and immunology. Life cycle The life cycle of ''T. regenti'' is analogous to that of human schistosomes. Adult flukes mate in a nasal mucosa of anatid birds (e.g. ''Anas platyrhynchos, Spatula clypeata'' or ''Cairina moschata'') and produce eggs with miracidia which hatch directly in the host tissue and leak outside when the bird is drinking/feeding. Once in water, the miracidia swim using their cilia and actively search for a proper molluscan intermediate host (''Radix lagotis, Rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obligate Parasite
An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate. It is advantageous for the parasite to preserve the health of their host when this is compatible with their nutritional and reproductive requirements, except when the death of the host is necessary for transmission.Combes, C. (1997) Fitness of Parasites: Pathology and Selection ''International Journal for Parasitology'' 27 (1): 1–10. Species Obligate parasitism is exhibited in a range of organisms, with examples in viruses, bacteria, fungi, plants, and animals.Balashov, Yu.S. (2011) Parasitism and Ecological Paras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parasitism
Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of life. The entomologist E. O. Wilson has characterised parasites as "predators that eat prey in units of less than one". Parasites include single-celled protozoans such as the agents of malaria, sleeping sickness, and amoebic dysentery; animals such as hookworms, lice, mosquitoes, and vampire bats; fungi such as Armillaria mellea, honey fungus and the agents of ringworm; and plants such as mistletoe, dodder, and the Orobanchaceae, broomrapes. There are six major parasitic Behavioral ecology#Evolutionarily stable strategy, strategies of exploitation of animal hosts, namely parasitic castration, directly transmitted parasitism (by contact), wikt:trophic, trophicallytransmitted parasitism (by being eaten), Disease vector, vector-transmitted paras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schistosoma Malayensis
''Schistosoma malayensis'' is a schistosome parasite. It was first described in 1988 in Peninsular Malaysia and appears to be a zooenotic infection. The species is named after the country of Malaysia. The natural vertebrate host is van Müller's rat (''Rattus muelleri''). The intermediate hosts are aquatic snails, ''Robertsiella kaporenisis''. Among ''Robertsiella kaporenisis'' are two other ''Roberstiella'' species. Among humans exposed to this parasite the lifetime incidence appears to be 5–10%.Sagin D.D., Ismail G., Fui J.N., Jok J.J. (2001) ''Schistosomiasis malayensis''-like infection among the Penan and other interior tribes (Orang Ulu) in upper Rejang River Basin Sarawak Malaysia. Southeast Asian J. Trop. Med. Public Health 32(1):27–32 The symptoms are unclear, because the symptoms have never been reported. The disease has been little studied and it is currently considered to be a relatively minor public health problem. Taxonomy ''Schistosoma malayensis'' is a member ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swimmer's Itch
Swimmer's itch, cercarial dermatitis or schistosome dermatitis is a short-term allergic contact dermatitis occurring in the skin of humans that have been infected by water-borne schistosomes, a type of flatworm. It is common in freshwater, brackish and marine habitats worldwide. The incidence of this condition may be increasing, although this may be attributed to better monitoring and reporting. Nevertheless, the condition is considered to be an emerging infectious disease. The main symptom is itchy papules (raised skin) that commonly occur within 2 days of infection. Initially, wheals develop quickly, then turn into maculae in about half an hour. Within 10–12 hours these turn into very itchy papules that reach their worst by the second or third day. The papules disappear in 1–2 weeks but secondary effects from scratching can continue longer. The intense itching, which peaks after 48–72 hours, is associated with pain and swelling of the affected areas. People repeatedly expo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schistosomiasis
Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody stool, or blood in the urine. Those who have been infected for a long time may experience liver damage, kidney failure, infertility, or bladder cancer. In children, it may cause poor growth and learning difficulty. The disease is spread by contact with fresh water contaminated with the parasites. These parasites are released from infected freshwater snails. The disease is especially common among children in developing countries, as they are more likely to play in contaminated water. Other high-risk groups include farmers, fishermen, and people using unclean water during daily living. It belongs to the group of helminth infections. Diagnosis is by finding eggs of the parasite in a person's urine or stool. It can also be confirmed by fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lancetfish
Lancetfishes are large oceanic predatory fishes in the genus ''Alepisaurus'' ("scaleless lizard") in the monogeneric family Alepisauridae. Lancetfishes grow up to in length. Very little is known about their biology, though they are widely distributed in all oceans, except the polar seas. Specimens have been recorded as far north as Greenland. They are often caught as bycatch by vessels long-lining for tuna. The generic name is from Greek ''a-'' meaning "without", ' meaning "scale", and ''sauros'' meaning "lizard". Species The two currently recognized extant species in this genus are: * ''Alepisaurus brevirostris'' Gibbs, 1960 (short-snouted lancetfish) * '' Alepisaurus ferox'' R. T. Lowe, 1833 (long-snouted lancetfish) The anatomic difference between the two species is the shape of the snout, which is long and pointed in ''A. ferox'', and slightly shorter in ''A. brevirostris''. The long-snouted lancefish is found in the tropical and northern sub-tropical waters of the Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
