Histomonas meleagridis | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Phylum: | Metamonada |
Order: | Tritrichomonadida |
Family: | Dientamoebidae |
Genus: | Histomonas Tyzzer, 1920 [1] |
Species: | H. meleagridis |
Binomial name | |
Histomonas meleagridis (Smith, 1895) | |
Histomonas meleagridis is a species of parasitic protozoan that infects a wide range of birds including chickens, turkeys, peafowl, quail and pheasants, causing infectious enterohepatitis, or histomoniasis (blackhead diseases). H. meleagridis can infect many birds, but it is most deadly in turkeys. It inhabits the lumen of cecum and parenchyma of liver, where it causes extensive necrosis. It is transmitted by another cecal parasite, the nematode Heterakis gallinarum .
Histomonas meleagridis is a microscopic, pleomorphic protozoan, and can exist in two forms, amoeboid and flagellated. Within the tissue, it is present as an amoeboid protozoan, while in the lumen or free in the contents of cecum, it lives as an elongated flagellated form. The amoeboid form is typically 8–15 μm in diameter, whereas the flagellated form can reach up to 30 μm in diameter. [2] Histomonads do not possess mitochondria, but instead produce energy inside hydrogenosomes. [3] The flagellum shows the common 9x2+2 type. [3]
Histomonas meleagridis reproduces by binary fission. The free trophozoites are very delicate and can survive only for a few hours in the external environment. However, when they are transmitted between flocks in the eggs of Heterakis gallinarum , a cecal nematode, which in turn can be transmitted by earthworms that ingested the nematode eggs, they gain entry into the nematode eggs. The eggs with the trophozoites are passed out into the environment through the feces. In this way, the trophozoites can remain viable up to two years in the external environment. [2] Within turkey flocks H. meleagridis is also known to be directly transmitted from bird to bird. Histomonads, either released from the heterakid nematode larvae in the ceca or after direct infection via the cloaca, replicate rapidly in the cecal tissues. [4] They migrate to the submucosa and muscularis mucosae and cause severe necrosis. The parasites then move to the liver through the vascular system. There, they cause typical crater-like necrotic lesions. [5] Mortality in turkey flocks can be very high (80-100%). [6]
Histomonas meleagridis is the causal organism of histomoniasis of gallinaceous birds. It induces extensive and severe necrosis of the tissues of the mucosa and submucosa of cecum and parenchyma of the liver. The lesions are sometimes exacerbated by other pathogens such as Escherichia coli and coccidia. [7] The symptoms appear within seven to 12 days after infection, and include depression, reduced appetite, poor growth, increased thirst, sulphur-yellow diarrhoea, listlessness, drooping wings, and unkempt feathers. [5] The symptoms are highly fatal to turkeys, but effect less damage in chickens. However, outbreaks in chickens may result in high morbidity, moderate mortality, and extensive culling, leading to overall poor flock performance. [6] Concurrence of Salmonella typhmurium and E. coli was found to cause high mortality in broiler chickens. [7] Young birds, particularly those three to 12 weeks old, are most susceptible. Generally, the symptoms are profound in turkeys, while chickens are usually asymptomatic. [2]
Diagnosis can be easily performed by necropsy of the fresh or preserved carcass, particularly on the liver. Recently paromomycin has been approved by the Italian authorities for treatment (Paromomicina 200 mg/g Huvepharma). However good management of the farm and sanitation are the essential effective strategies to control the spread of infection. [8] [9]
Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it forms a synthesis of other disciplines, and draws on techniques from fields such as cell biology, bioinformatics, biochemistry, molecular biology, immunology, genetics, evolution and ecology.
Eimeria tenella is a species of Eimeria that causes hemorrhagic cecal coccidiosis in young poultry. It is found worldwide.
Eimeria is a genus of apicomplexan parasites that includes various species capable of causing the disease coccidiosis in animals such as cattle, poultry and smaller ruminants including sheep and goats. Eimeria species are considered to be monoxenous because the life cycle is completed within a single host, and stenoxenous because they tend to be host specific, although a number of exceptions have been identified. Species of this genus infect a wide variety of hosts. Thirty-one species are known to occur in bats (Chiroptera), two in turtles, and 130 named species infect fish. Two species infect seals. Five species infect llamas and alpacas: E. alpacae, E. ivitaensis, E. lamae, E. macusaniensis, and E. punonensis. A number of species infect rodents, including E. couesii, E. kinsellai, E. palustris, E. ojastii and E. oryzomysi. Others infect poultry, rabbits and cattle. For full species list, see below.
Poultry diseases occur in poultry, which are domesticated birds kept for their meat, eggs or feathers. Poultry species include the chicken, turkey, duck, goose and ostrich.
Ascaridia galli is a parasitic roundworm belonging to the phylum Nematoda. Nematodes of the genus Ascaridia are essentially intestinal parasites of birds. A. galli is the most prevalent and pathogenic species, especially in domestic fowl, Gallus domesticus. It causes ascaridiasis, a disease of poultry due to heavy worm infection, particularly in chickens and turkeys. It inhabits the small intestine, and can be occasionally seen in commercial eggs.
Balantidiasis is a protozoan infection caused by infection with Balantidium coli.
Trichomonadida is an order of anaerobic protists, included with the parabasalids. Members of this order are referred to as trichomonads.
Babesia, also called Nuttallia, is an apicomplexan parasite that infects red blood cells and is transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș in 1888, over 100 species of Babesia have since been identified.
Eimeria meleagridis is a species of coccidia found worldwide, which causes mild disease in young turkeys aged 4–8 weeks. The parasite causes disease in the cecum, where, on post-mortem examination (necropsy), a cream-colored exudate is seen.
Carbarsone is an organoarsenic compound used as an antiprotozoal drug for treatment of amebiasis and other infections. It was available for amebiasis in the United States as late as 1991. Thereafter, it remained available as a turkey feed additive for increasing weight gain and controlling histomoniasis.
Chilomastix mesnili is a non-pathogenic member of primate gastrointestinal microflora, commonly associated with but not causing parasitic infections. It is found in about 3.5% of the population in the United States. In addition to humans, Chilomastix is found in chimpanzees, orangutans, monkeys, and pigs. It lives in the cecum and colon. C. mesnili has a similar life style to Giardia lamblia.
Protozoan infections are parasitic diseases caused by organisms formerly classified in the kingdom Protozoa. These organisms are now classified in the supergroups Excavata, Amoebozoa, Harosa, and Archaeplastida. They are usually contracted by either an insect vector or by contact with an infected substance or surface.
Heterakis gallinarum is a nematode parasite that lives in the cecum of some galliform birds, particularly in ground feeders such as domestic chickens and turkeys. It causes infection that is mildly pathogenic. However, it often carries a protozoan parasite Histomonas meleagridis which causes of histomoniasis. Transmission of H. meleagridis is through the H. gallinarum egg. H. gallinarum is about 1–2 cm in length with a sharply pointed tail and a preanal sucker. The parasite is a diecious species with marked sexual dimorphism. Males are smaller and shorter, measuring around 9 mm in length, with a unique bent tail. Females are stouter and longer, measuring roughly 13 mm in length, with a straight tail end.
Ascaridia is a genus of parasitic nematodes. Members of the genus are primarily intestinal parasites of birds. Three species are well known, namely, A. galli found mostly in chickens, A. dissimilis in turkeys, and A. columbae in pigeons. Lesser known species such as A. hermaphrodita, A. sergiomeirai, A. ornata, A. nicobarensis, and A. platyceri are found in parrots.
Raillietina is a genus of tapeworms that includes helminth parasites of vertebrates, mostly of birds. The genus was named in 1920 in honour of a French veterinarian and helminthologist, Louis-Joseph Alcide Railliet. Of the 37 species recorded under the genus, Raillietina demerariensis, R. asiatica, and R. formsana are the only species reported from humans, while the rest are found in birds. R. echinobothrida, R. tetragona, and R. cesticillus are the most important species in terms of prevalence and pathogenicity among wild and domestic birds.
Raillietina echinobothrida is a parasitic tapeworm belonging to the class Cestoda. It is the most prevalent and pathogenic helminth parasite in birds, particularly in domestic fowl, Gallus domesticus Linnaeus, 1758. It requires two hosts, birds and ants, for completion of its life cycle. It is a hermaphrodite worm having both the male and female reproductive organs in its body. The parasite is responsible for 'nodular tapeworm disease' in poultry.
Heterakis is a genus of parasitic nematodes. Members of the genus are minute roundworms (pinworms), hardly 1 cm long, infecting different species of gallinaceous birds, including chickens, turkeys, ducks, geese, grouse, guineafowl, partridges, pheasants, and quail. About 10 species are placed in the genus, but classification is often ambiguous due to their close resemblance, and a number of synonyms have arisen. H. gallinarumSchrank, 1788; H. isolonchevon Linstow, 1906; and H. disparSchrank, 1870 are the best understood species in terms of prevalence, pathogenicity, and biology. They inhabit the lumen of the cecum of the host.
Histomoniasis is a commercially significant disease of poultry, particularly of chickens and turkeys, due to parasitic infection of a protozoan, Histomonas meleagridis. The protozoan is transmitted to the bird by the nematode parasite Heterakis gallinarum. H. meleagridis resides within the eggs of H. gallinarum, so birds ingest the parasites along with contaminated soil or food. Earthworms can also act as a paratenic host.
Dientamoeba fragilis is a species of single-celled excavates found in the gastrointestinal tract of some humans, pigs and gorillas. It causes gastrointestinal upset in some people, but not in others. It is an important cause of traveller's diarrhoea, chronic diarrhoea, fatigue and, in children, failure to thrive. Despite this, its role as a "commensal, pathobiont, or pathogen" is still debated. D. fragilis is one of the smaller parasites that are able to live in the human intestine. Dientamoeba fragilis cells are able to survive and move in fresh feces but are sensitive to aerobic environments. They dissociate when in contact or placed in saline, tap water or distilled water.
Chilomastix is a genus of pyriform excavates within the family Retortamonadidae All species within this genus are flagellated, structured with three flagella pointing anteriorly and a fourth contained within the feeding groove. Chilomastix also lacks Golgi apparatus and mitochondria but does possess a single nucleus. The genus parasitizes a wide range of vertebrate hosts, but is known to be typically non-pathogenic, and is therefore classified as harmless. The life cycle of Chilomastix lacks an intermediate host or vector. Chilomastix has a resistant cyst stage responsible for transmission and a trophozoite stage, which is recognized as the feeding stage. Chilomastix mesnili is one of the more studied species in this genus due to the fact it is a human parasite. Therefore, much of the information on this genus is based on what is known about this one species.
Hauck, Ruediger; Hafez, Hafez M. (2012). "Pigeons are Not Susceptible to Intracloacal Infection with Histomonas meleagridis" (PDF). Pakistan Veterinary Journal. 32 (4): 597–600. Retrieved 24 July 2016.
Billic, Ivana; Jaskulska, Barbara; Souillard, Rozenn; Liebhart, Dieter; Hess, Michael (21 March 2014). "Multi-Locus Typing of Histomonas meleagridis Isolates Demonstrates the Existence of Two Different Genotypes". PLOS ONE. 9 (3): e92438. Bibcode:2014PLoSO...992438B. doi: 10.1371/journal.pone.0092438 . PMC 3962415 . PMID 24658534.
Hauck, Ruediger; Hafez, Hafez M. (January 2013). "Experimental infections with the protozoan parasite Histomonas meleagridis: a review". Parasitology Research. 1 (112): 19–34. doi:10.1007/s00436-012-3190-5. PMID 23160894. S2CID 14662327.