Histomonas meleagridis

Histomonas meleagridis
Scientific classification
Domain:	Eukaryota
(unranked):	Excavata
Phylum:	Metamonada
Class:	Parabasalia
Order:	Trichomonadida
Family:	Monocercomonadidae
Genus:	Histomonas
Species:	H. meleagridis
Binomial name
	Histomonas meleagridis; (Smith, 1895)

Last updated April 23, 2024

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 .

Description

H. 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.^[1] Histomonads do not possess mitochondria, but instead produce energy inside hydrogenosomes.^[2] The flagellum shows the common 9x2+2 type.^[2]

Lifecycle

H. 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.^[1] 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.^[3] 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.^[4] Mortality in turkey flocks can be very high (80-100%).^[5]

Pathogenicity

H. 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.^[6] 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.^[4] 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.^[5] Concurrence of Salmonella typhmurium and E. coli was found to cause high mortality in broiler chickens.^[6] Young birds, particularly those three to 12 weeks old, are most susceptible. Generally, the symptoms are profound in turkeys, while chickens are usually asymptomatic.^[1]

Diagnosis and control

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.^[7]^[8]

Related Research Articles

Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of a sexually transmitted disease called trichomoniasis. It is the most common pathogenic protozoan that infects humans in industrialized countries. Infection rates in men and women are similar but women are usually symptomatic, while infections in men are usually asymptomatic. Transmission usually occurs via direct, skin-to-skin contact with an infected individual, most often through vaginal intercourse. The WHO has estimated that 160 million cases of infection are acquired annually worldwide. The estimates for North America alone are between 5 and 8 million new infections each year, with an estimated rate of asymptomatic cases as high as 50%. Usually treatment consists of metronidazole and tinidazole.

A trophozoite is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing Plasmodium falciparum and those of the Giardia group. The complementary form of the trophozoite state is the thick-walled cyst form. They are often different from the cyst stage, which is a protective, dormant form of the protozoa. Trophozoites are often found in the host's body fluids and tissues and in many cases, they are the form of the protozoan that causes disease in the host. In the protozoan, Entamoeba histolytica it invades the intestinal mucosa of its host, causing dysentery, which aid in the trophozoites traveling to the liver and leading to the production of hepatic abscesses.

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.

Megaloschizonts are large schizonts that produce extremely high numbers of merozoites. They are found in various species of the Phylum Apicomplexa. The Apicomplexa phylum contains several parasitic protozoans. They have a very complex life cycle that includes several stages. Megaloschizonts and the smaller schizonts are the part of the life cycle that takes place inside the infected host organism and operates as an asexually reproductive cell. Megaloschizonts appear as grey-white nodules found in the smooth muscle of major organs, such as the heart, liver, lung or spleen.

Blastocystis is a genus of single-celled parasites belonging to the Stramenopiles that includes algae, diatoms, and water molds. There are several species, living in the gastrointestinal tracts of species as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches. Blastocystis has low host specificity, and many different species of Blastocystis can infect humans, and by current convention, any of these species would be identified as Blastocystis hominis.

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.

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

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 travellers 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.

Egg drop syndrome '76 is a viral disease that affects birds, notably chickens, ducks, geese and swans. It is characterised by a sudden drop in production of eggs as well as its eggshell quality in apparent healthy laying birds.

Naegleria fowleri, also known as the brain-eating amoeba, is a species of the genus Naegleria. It belongs to the phylum Percolozoa and is technically classified as an amoeboflagellate excavate, rather than a true amoeba. This free-living microorganism primarily feeds on bacteria but can become pathogenic in humans, causing an extremely rare, sudden, severe, and usually fatal brain infection known as naegleriasis or primary amoebic meningoencephalitis (PAM).

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.

References

1 2 3 Griffiths HJ (1978). A Handbook of Veterinary Parasitology: Domestic Animals of North America. University of Minnesota Press, Minneapolis, Minnesota, USA, pp. 23-25. ISBN 0-8166-0828-8
1 2 Mielewczik, Michael; Mehlhorn, Heinz; Al-Quraishy, Saleh; Grabensteiner, E.; Hess, M. (1 September 2008). "Transmission electron microscopic studies of stages of Histomonas meleagridis from clonal cultures". Parasitology Research. 103 (4): 745–50. doi:10.1007/s00436-008-1009-1. ISSN 0932-0113. PMID 18626664. S2CID 2331300.
↑ Hu J, McDougald LR (2003). "Direct lateral transmission of Histomonas meleagridis in turkeys". Avian Diseases. 47 (2): 489–492. doi:10.1637/0005-2086(2003)047[0489:DLTOHM]2.0.CO;2. PMID 12887212. S2CID 22568033.
1 2 McDougald LR (2005). "Blackhead disease (histomoniasis) in poultry: a critical review". Avian Diseases. 49 (4): 462–476. doi:10.1637/7420-081005R.1. PMID 16404985. S2CID 43031620.
1 2 McDougald LR (1998). "Intestinal protozoa important to poultry". Poultry Science. 77 (8): 1156–1158. doi: 10.1093/ps/77.8.1156 . PMID 9706082.
1 2 Ganapathy K, Salamat MH, Lee CC, Johara MY (2000). "Concurrent occurrence of salmonellosis, colibaccillosis and histomoniasis in a broiler flock fed with antibiotic-free commercial feed". Avian Pathology. 29 (6): 639–642. doi: 10.1080/03079450020016000 . PMID 19184862. S2CID 25256520.
↑ Ballweber LR (2001). Veterinary parasitology: The Practical Veterinarian. Butterworth–Heinemann, Woburn, MA, USA, pp. 279-280. ISBN 0-7506-7261-7
↑ Callait-Cardinal MP, Gilot-Fromont E, Chossat L, Gonthier A, Chauve C, Zenne L (2010). "Flock management and histomoniasis in free-range turkeys in France: description and search for potential risk factors". Epidemiology and Infection. 138 (3): 353–363. doi: 10.1017/S0950268809990562 . PMID 19664306. S2CID 11535496.