Echinostoma

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Echinostoma
Echinostoma revolutum.png
Two specimens of Echinostoma revolutum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Plagiorchiida
Family: Echinostomatidae
Subfamily: Echinostomatinae
Genus: Echinostoma
Rudolphi, 1809 [1]

Echinostoma is a genus of trematodes (flukes), which can infect both humans and other animals. These intestinal flukes have a three-host life cycle with snails or other aquatic organisms as intermediate hosts, [2] and a variety of animals, including humans, as their definitive hosts.

Contents

Echinostoma infect the gastrointestinal tract of humans, and can cause a disease known as echinostomiasis. The parasites are spread when humans or animals eat infected raw or undercooked food, such as bivalve molluscs or fish. [3]

Taxonomy

There has been debate about the number of species in this group, with estimates as high as 120 unique species of Echinostoma, [4] however, currently 16 species have been accepted as valid species with another 10 to be validated [5] Echinostoma are difficult to classify based on morphology alone. Many species look alike and can be considered cryptic species (different lineages are considered to be the same species, due to high morphological similarity between them). [6] Many species of Echinostoma have been re-classified several times. For example, the species now known as Echinostoma caproni , was previously known by a variety of names including E. liei, E. paraensei and E. togoensis. [4]

Methods for classifying Echinostoma species, such as the Echinostoma revolutum group, were devised by Kanev. [7] The Echinostoma species in this group are now classified according to their shared morphological and biological characteristics, such as the presence of 37 collar spines. [7]

Molecular methods, such as sequencing mitochondrial DNA and ribosomal DNA, are also used to distinguish between species of Echinostoma as an alternative to morphological classification methods. [8]

Species

Phylogeny of most known Echinostoma species based on the mitochondrial nad1 sequences: [5]

Echinostoma

E. mekongi Cho, Jung, Chang, Sohn, Sinuon & Chai, 2020

E. deserticum Kechemir, Jourdane & Mas-Coma, 2002

E. paraulum Dietz, 1909

E. cinetorchis Ando & Ozaki, 1923

E. robustum Yamaguti, 1935

E. miyagawai Ishii, 1932

E. novaezealandense Georgieva, Blasco-Costa & Kostadinova, 2017

E. revolutum (Froehlich, 1802)

E. caproni Richard, 1964 (previously E. liei)

E. trivolvis (Cort, 1914) Kanev, 1985

E. paraensei Lie & Basch, 1967

E. nasincovae Faltýnková, Georgieva, Soldánová & Kostadinova, 2015

E. bolschewense (Kotova, 1939) Našincová, 1991

Further confirmed species are E. lindoense Sandground & Bonne, 1940 and E. luisreyi Maldonado, Vieira & Lanfredi, 2003, these are not included in the phylogeny because of a lack of genetic material. [5] Unconfirmed species are E. acuticauda , E. barbosai , E. chloephagae , E. echinatum , E. jurini , E. nudicaudatum , E. parvocirrus , E. pinnicaudatum , E. ralli , and E. rodriguesi . [5]

Morphology

Cercariae of various echinostome species Parasite210057-fig7 Diversity of echinostomes (Digenea Echinostomatidae) in their snail hosts at high latitudes.png
Cercariae of various echinostome species

Echinostoma are internal digenean trematode parasites which infect the intestines and bile duct [4] of their hosts.

The length and width of adult Echinostoma varies between species, but they tend to be approximately 2-10mm × 1-2mm in size. [9]

Adult Echinostoma have two suckers: an anterior oral sucker and a ventral sucker. [4] They also have a characteristic head collar with spines surrounding their oral sucker. [10] The number of collar spines varies between Echinostoma species, but there are usually between 27 and 51. [4] These spines can be arranged in one or two circles around the sucker, and their arrangement may be a characteristic feature of an Echinostoma species. [4]

Echinostoma have a digestive system consisting of a pharynx, oesophagus and an excretory pore. [4]

Echinostoma are hermaphrodites, [10] and have both male and female reproductive organs. The testes are found in the posterior part of the fluke's body, in the area furthest from the mouth. [4] The ovary is also found in this location, close to the testes. [4]

The eggs (ova) of Echinostoma are operculate [4] and vary in size, but are typically in the range of 80–135 × 55–80 μm. [11]

Geographic distribution

The genus Echinostoma has a global distribution. These parasites are particularly common in South East Asia, in countries such as South Korea and the Philippines. [12] However, they are also found in some European countries, [7] and species such as Echinostoma trivolvis are found in North America. [13]

Life cycle

Echinostoma have three hosts in their life cycle: a first intermediate host, a second intermediate host and a definitive host. Snail species such as Lymnaea spp. are common intermediate hosts for Echinostoma, [4] although fish and other bivalve molluscs can also be intermediate hosts for these parasites. [14] [15]

Echinostoma species have low specificity for their definitive hosts, and can infect a variety of different species of animal, including amphibians, [16] aquatic birds, mammals and humans. [14] A definitive host which is infected with Echinostoma will shed unembryonated Echinostoma eggs in their faeces. When the eggs are in contact with fresh water they may become embryonated, and will then hatch and release miracidia. [3] The miracidia stage of Echinostoma is free-swimming, and actively penetrates the first intermediate snail host, which then becomes infected. [3]

Life cycle of Echinostoma. Echinostomiasis Life Cycle no watermark.gif
Life cycle of Echinostoma.

In the first intermediate host, the miracidium undergoes asexual reproduction [17] for several weeks, which includes sporocyst formation, a few generations of rediae and the production of cercariae. [3] The cercariae are released from the snail host into water and are also free-swimming. The cercariae penetrate a second intermediate host, or they remain in the first intermediate host, where they form metacercariae. [14] Definitive hosts become infected by eating secondary hosts which are infected with metacercariae. [14] Once the metacercariae have been eaten, they excyst in the intestine of the definitive host [14] where the parasite then develops into an adult.

Echinostoma are hermaphrodites. A single adult individual has both male and female reproductive organs, and is capable of self-fertilization. [17] Sexual reproduction of adult Echinostoma in the definitive host leads to the production of unembryonated eggs. [3] The life cycle of Echinostoma is temperature dependent, and occurs quicker at higher temperatures. [4] Echinostoma eggs can survive for about 5 months and still have the ability to hatch and develop into the next life cycle stage. [18]

Echinostomiasis

Infection of humans with members of the family Echinostomatidae, including Echinostoma, can lead to a disease called echinostomiasis. E. revolutum, E. echinatum, E. malaynum and E. hortense are particularly common causes of Echinostoma infections in humans. [4] Humans can become infected with Echinostoma by eating infected raw or undercooked food, particularly fish, clams and snails. [3] Infection with these parasites tends to be common in regions where cultural dishes require the use of raw or undercooked food that may be infected with Echinostoma. [19] A mild infection may not have any symptoms. [20] If symptoms are present they can include abdominal pain, diarrhoea, tiredness and weight loss. [3]

Epidemiology of echinostomiasis

Echinostomiasis is endemic in South East Asia and the Far East, in countries including China, Korea, Taiwan, Philippines, Malaysia, Indonesia and India. [21] Echinostomiasis has also been reported in Japan, Singapore, Romania, Hungary and Italy. [21] The prevalence of echinostomiasis varies between countries [21] but there tend to be foci of infection in areas where raw or undercooked hosts of Echinostoma, such as snails or fish, are widely consumed. [20]

Pathogenesis

Echinostoma are not highly pathogenic. [20] Symptoms of greater severity tend to be seen in an echinostomiasis infection where there is a higher number of flukes. [20] The flukes cause damage to the intestinal mucosa, which leads to ulceration and inflammation. [20]

Diagnosis

Unstained Echinostoma egg. Unstained Echinostoma egg.jpg
Unstained Echinostoma egg.

An Echinostoma infection can be diagnosed by observing the parasite eggs in the faeces of an infected individual, under a microscope. Methods such as the Kato-Katz procedure can be used to do this. [3] The eggs typically have a yellow-brown appearance, and are ellipsoid in shape. [20] To confirm which species is causing the infection adult worms must be recovered from the infected individual, such as with anthelmintic treatment. [20]

Treatment and prevention

Echinostomiasis can be treated with the anthelmintic drug praziquantel, as for other intestinal trematode infections. [3] Side effects of anthelmintic drug treatment may include nausea, abdominal pain, headaches or dizziness. [3] [22]

Echinostomiasis can be controlled at the same time as other food-borne parasite infections, using existing control programmes. [21] Interrupting the parasite's lifecycle by efficient diagnosis and subsequent treatment of infected individuals, and preventing reinfection, may help to control this disease. [23] As echinostomiasis is acquired through the consumption of raw or undercooked infected food, cooking food thoroughly will prevent infection.

Related Research Articles

<span class="mw-page-title-main">Trematoda</span> Class of parasitic flatworms

Trematoda is a class of flatworms known as flukes or trematodes. 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, 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.

<span class="mw-page-title-main">Digenea</span> Class of flukes

Digenea is a class of trematodes in the Platyhelminthes phylum, consisting of parasitic flatworms 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.

<span class="mw-page-title-main">Fasciolopsiasis</span> Medical condition

Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans, growing up to 7.5 cm (3.0 in) long.

<span class="mw-page-title-main">Trematode life cycle stages</span>

Trematodes are parasitic flatworms of the class Trematoda, specifically parasitic flukes with two suckers: one ventral and the other oral. Trematodes are covered by a tegument, that protects the organism from the environment by providing secretory and absorptive functions.

Opisthorchis viverrini, common name Southeast Asian liver fluke, is a food-borne trematode parasite from the family Opisthorchiidae that infects the bile duct. People are infected after eating raw or undercooked fish. Infection with the parasite is called opisthorchiasis. O. viverrini infection also increases the risk of cholangiocarcinoma, a cancer of the bile ducts.

<span class="mw-page-title-main">Paragonimiasis</span> Medical condition

Paragonimiasis is a food-borne parasitic disease caused by several species of lung flukes belonging to genus Paragonimus. Infection is acquired by eating crustaceans such as crabs and crayfishes which host the infective forms called metacercariae, or by eating raw or undercooked meat of mammals harboring the metacercariae from crustaceans.

<i>Dicrocoelium dendriticum</i> Species of fluke

Dicrocoelium dendriticum, the lancet liver fluke, is a parasite fluke that tends to live in cattle or other grazing mammals.

<i>Fasciolopsis</i> Genus of flukes

Fasciolopsis is a genus of trematodes. They are also known as giant intestinal flukes.

<i>Nanophyetus</i> Genus of flukes

Nanophyetus salmincola is a food-borne intestinal trematode parasite prevalent on the Pacific Northwest coast. The species may be the most common trematode endemic to the United States.

<i>Echinostoma revolutum</i> Species of fluke

Echinostoma revolutum is a trematode parasite of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.

<i>Heterophyes heterophyes</i> Species of fluke

Heterophyes heterophyes, or the intestinal fish fluke, was discovered by Theodor Maximaillian Bilharz in 1851. This parasite was found during an autopsy of an Egyptian mummy. H. heterophyes is found in the Middle East, West Europe and Africa. They use different species to complete their complex lifestyle. Humans and other mammals are the definitive host, first intermediate host are snails, and second intermediate are fish. Mammals that come in contact with the parasite are dogs, humans, and cats. Snails that are affected by this parasite are the Cerithideopsilla conica. Fish that come in contact with this parasite are Mugil cephalus, Tilapia milotica, Aphanius fasciatus, and Acanthgobius sp. Humans and mammals will come in contact with this parasite by the consumption of contaminated or raw fish. This parasite is one of the smallest endoparasite to infect humans. It can cause intestinal infection called heterophyiasis.

Echinostoma hortense is an intestinal fluke of the class Trematoda, which has been found to infect humans in East Asian countries such as Korea, China, and Japan. This parasite resides in the intestines of birds, rats and other mammals such as humans. While human infections are very rare in other regions of the world, East Asian countries have reported human infections up to about 24% of the population in some endemic sub-regions. E. hortense infections are zoonotic infections, which occurs from eating raw or undercooked freshwater fish. The primary disease associated with an E. hortense infection is called echinostomiasis, which is a general name given to diseases caused by Trematodes of the genus Echinostoma.

Echinostoma cinetorchis is a species of human intestinal fluke, a trematode in the family Echinostomatidae.

<i>Alaria</i> (flatworm) Genus of flukes

Alaria is a genus of flatworms, or trematodes, in the family Diplostomidae.

Paragonimus kellicotti, the North American lung fluke, is a species of parasitic trematode in the genus Paragonimus. This species of Paragonimus has an intricate lifecycle, and although its name may suggest that it is only a health concern in North America, it is also prominent in Southeast Asia and China.

Echinostoma caproni is a species of 37-spined Egyptian echinostome. It is naturally found in Cameroon, Congo, Egypt, Madagascar, and Togo.

<i>Metagonimus yokogawai</i> Species of fluke

Metagonimus yokogawai, or the Yokogawa fluke, is a species of a trematode, or fluke worm, in the family Heterophyidae.

<span class="mw-page-title-main">Trematodiasis</span> Medical condition

Trematodiasis is a group of parasitic infections caused by different species of flukes, in humans mainly by digenean trematodes. Symptoms can range from mild to severe depending on the species, number and location of trematodes in the infected organism. Symptoms depend on type of trematode present, and include chest and abdominal pain, high temperature, digestion issues, cough and shortness of breath, diarrhoea and change in appetite.

Echinostoma bolschewense is a species of echinostome from the Czech Republic, Russia, and the Slovak Republic.

<span class="mw-page-title-main">Gastropod-borne parasitic disease</span> Medical condition

Gastropod-borne parasitic diseases (GPDs) are a group of infectious diseases that require a gastropod species to serve as an intermediate host for a parasitic organism that can infect humans upon ingesting the parasite or coming into contact with contaminated water sources. These diseases can cause a range of symptoms, from mild discomfort to severe, life-threatening conditions, with them being prevalent in many parts of the world, particularly in developing regions. Preventive measures such as proper sanitation and hygiene practices, avoiding contact with infected gastropods and cooking or boiling food properly can help to reduce the risk of these diseases.

References

  1. ↑ Rudolphi K. (1809). Entoz. Hist. Nat.2(1): 38.
  2. ↑ Pantoja, Camila; Faltýnková, Anna; O’Dwyer, Katie; Jouet, Damien; Skírnisson, Karl; Kudlai, Olena (2021). "Diversity of echinostomes (Digenea: Echinostomatidae) in their snail hosts at high latitudes". Parasite. 28: 59. doi:10.1051/parasite/2021054. ISSN   1776-1042. PMC   8336728 . Open Access logo PLoS transparent.svg
  3. 1 2 3 4 5 6 7 8 9 10 Toledo R; Esteban JG; Fried B (1995). "Current status of food-borne trematode infections". European Journal of Clinical Microbiology and Infectious Diseases . 31 (8): 1705–1718. doi:10.1007/s10096-011-1515-4.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 Huffman, Jane E.; Fried, Bernard (1990). "Echinostoma and Echinostomiasis". Advances in Parasitology. 29: 215–269. doi:10.1016/S0065-308X(08)60107-4.
  5. 1 2 3 4 Chai, Jong-Yil; Cho, Jaeeun; Chang, Taehee; Jung, Bong-Kwang; Sohn, Woon-Mok (2020). "Taxonomy of Echinostoma revolutum and 37-Collar-Spined Echinostoma spp.: A historical review". The Korean Journal of Parasitology. 58 (4): 343–371. doi: 10.3347/kjp.2020.58.4.343 . PMC   7462802 .
  6. ↑ Detwiler JT; Bos DH; Minchella DJ (2010). "Revealing the secret lives of cryptic species: Examining the phylogenetic relationships of echinostome parasites in North America". Molecular Phylogenetics and Evolution . 55 (2): 611–620. doi:10.1016/j.ympev.2010.01.004. PMID   20064622.
  7. 1 2 3 Kanev I (1994). "Life-cycle, delimitation and redescription of Echinostoma revolutum (Froelich, 1802) (Trematoda: Echinostomatidae)". Systematic Parasitology . 28 (2): 125–144. doi:10.1007/BF00009591.
  8. ↑ Morgan JA, Blair D (1998). "Relative merits of nuclear ribosomal internal transcribed spacers and mitochondrial CO1 and ND1 genes for distinguishing among Echinostoma species (Trematoda)". Parasitology . 116 (3): 289–297. doi:10.1017/s0031182097002217.
  9. ↑ Centers for Disease Control and Prevention. "Echinostomiasis". Archived from the original on 16 April 2014.
  10. 1 2 Gonçalves JP, Oliveira-Menezes A, Maldonado Junior A, et al. (2013). "Evaluation of Praziquantel effects on Echinostoma paraensei ultrastructure". Veterinary Parasitology . 194: 16–25. doi: 10.1016/j.vetpar.2012.12.042 .
  11. ↑ Centers for Disease Control and Prevention (29 November 2013). "Echinostomiasis". Archived from the original on 16 April 2014.
  12. ↑ Fürst T; Keiser J; Utzinger A (2012). "Global burden of human food-borne trematodiasis: a systematic review and meta-analysis". The Lancet Infectious Diseases . 12 (3): 210–221. doi:10.1016/S1473-3099(11)70294-8.
  13. ↑ Kanev I; Fried B; Dimitrov V; Radev V (1995). "Redescription of Echinostoma trivolvis (Cort, 1914) (Trematoda: Echinostomatidae) with a discussion on its identity". Systematic Parasitology . 32: 61–70. doi:10.1007/BF00009468.
  14. 1 2 3 4 5 Centers for Disease Control and Prevention (29 November 2013). "Echinostomiasis". Archived from the original on 17 April 2014.
  15. ↑ Richard, J.; Brygoo, E. R. (1978). "Cycle évolutif du Trématode Echinostoma caproni Richard, 1964 (Echinostomatoidea)". Annales de Parasitologie Humaine et Comparée. 53 (3): 265–275. doi: 10.1051/parasite/1978533265 . Open Access logo PLoS transparent.svg
  16. ↑ Belden LK (2006). "Impact of eutrophication on wood frog, Rana sylvatica, tadpoles infected with Echinostoma trivolvis cercariae". Canadian Journal of Zoology . 84 (9): 1315–1321. doi:10.1139/z06-119.
  17. 1 2 Trouvé S; Renaud F; Durand P; Jourdane J (1999). "Reproductive and mate choice strategies in the hermaphroditic flatworm Echinostoma caproni". Journal of Heredity . 90: 582–585. doi: 10.1093/jhered/90.5.582 .
  18. ↑ Christensen NØ; Frandsen F; Roushdy MZ (1980). "The influence of environmental conditions and parasite-intermediate host-related factors on the transmission of Echinostoma liei". Zeitschrift für Parasitenkunde . 63: 47–63. doi:10.1007/BF00927056.
  19. ↑ Keiser J, Utzinger J (2005). "Emerging foodborne trematodiasis". Emerging Infectious Diseases . 11 (10): 1507–1514. doi:10.3201/eid1110.050614. PMC   3366753 . PMID   16318688.
  20. 1 2 3 4 5 6 7 Carney WP (1991). "Echinostomiasis - a snail-borne intestinal trematode zoonosis". Southeast Asian Journal of Tropical Medicine and Public Health . 22: Suppl:206–211.
  21. 1 2 3 4 Fried B; Graczyk TK; Tamang L (2004). "Food-borne intestinal trematodiases in humans". Parasitology Research . 93 (2): 159–170. doi:10.1007/s00436-004-1112-x. PMID   15103556.
  22. ↑ Keiser J, Utzinger J (2004). "Chemotherapy for major food-borne trematodes: a review". Expert Opinion on Pharmacotherapy . 5 (8): 1711–1726. doi:10.1517/14656566.5.8.1711.
  23. ↑ Graczyk TK, Fried B (1998). "Echinostomiasis: a common but forgotten food-borne disease". The American Journal of Tropical Medicine and Hygiene . 58 (4): 501–504. doi: 10.4269/ajtmh.1998.58.501 .
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