View source for Biology:Mammomonogamus

{{Short description|Genus of roundworms}}
{{Speciesbox
| image =
| image_caption =
| taxon = Mammomonogamus laryngeus
| authority = Ryzhikovk, 1948
}}
'''''Mammomonogamus''''' is a [[Biology:Genus|genus]] of parasitic [[Biology:Nematode|nematode]]s of the family [[Biology:Syngamidae|Syngamidae]] that parasitise the respiratory tracts of [[Biology:Cattle|cattle]], [[Biology:Sheep|sheep]], goats, [[Biology:Deer|deer]], [[Biology:Cat|cat]]s, orangutans, and [[Biology:Elephant|elephant]]s. The nematodes can also infect humans and cause the disease called mammomonogamiasis.<ref name="Anderson1980">Anderson RC, Chabaud AG, Willmott S. CIH keys to the nematode parasites of vertebrates, no 7. Keys to genera of superfamily Strongyloidea. ''Commonwealth Agricultural Bureaux'', England, 1980.</ref> Several known species fall under the genus ''Mammomonogamus'', but the most common species found to infest humans is ''M. laryngeus''. Infection in humans is very rare, with only about 100 reported cases worldwide, and is assumed to be largely accidental.<ref name="Nosanchuk1995">Nosanchuk, J.S., Wade, S.E., and Landolf, M (1995). Case Report of and Description of Parasite in Mammomonogamus laryngeus (Human Syngamosis) Infection. ''J of Clinical Microbiology''. '''33''': 998–1000.</ref> Cases have been reported from the Caribbean,<ref name="Leiper1913">{{cite journal | author=Leiper RJ | title=Gapes in man, an occasional helminthic infection: a notice of its discovery by Dr A King in St Lucia | journal=Lancet | volume=i | year=1913 | pages=170 | doi=10.1016/S0140-6736(00)76203-9 | issue=4664 }}</ref> China,<ref name="Li1997">{{cite journal |vauthors=Li D, Li G, Zhan X | title=Three cases of human ''Mammomonogamus laryngeus'' infection | journal=Chin J Parasitol Parasit Dis | year=1997 | volume=15 | pages=281–4 }}</ref> Korea,<ref name="Kim1998">{{cite journal  |vauthors=Kim HY, Lee SM, Joo JE, etal | title=Human syngamosis: the first case in Korea  | year=1998 | journal=Thorax | volume=53 | pages=717–18 | doi=10.1136/thx.53.8.717 | pmid=9828862 | issue=8 | pmc=1745283}}</ref> Thailand,<ref name="Eamsobhana2006">{{cite journal | title=''Mammomonogamus'' roundworm (Nematoda: Syngamidae) recovered from the duodenum of a Thai patient: a first and unusual case originating in Thailand |vauthors=Eamsobhana P, Mongkolporn T, Punthuprapasa P, Yoolek A | year=2006 | journal=Trans R Soc Trop Med Hyg | volume=100 | pages=387–91 | doi=10.1016/j.trstmh.2005.05.018 | pmid=16257022 | issue=4 }}</ref> and Philippines.<ref name="StJohn1929">{{cite journal |vauthors=SaintJohn JH, Simmons JS, Gardner LL | year=1929 | title=Infestation of the lung by a nematode of the genus ''Cyathostoma'' | journal=J Am Med Assoc | volume=92 | issue=22 | pages=1816–18 | doi=10.1001/jama.1929.02700480006003 }}</ref>

The worm usually inhabits the upper-respiratory region in the trachea, bronchus, or [[Medicine:Larynx|larynx]], and can elicit chronic coughing and [[Medicine:Asthma|asthma]]-like symptoms.<ref name="Weinstein1971">Weinstein, L., and A. Molovi. 1971. Syngamus laryngeus infection (Syngamosis) with chronic cough. Ann. Intern. Med. 74:577–580.</ref> One interesting case from Thailand reported finding worms in the patient's duodenum, suggesting ''M. laryngeus'' can also be a gastrointestinal [[Biology:Parasite|parasite]].<ref name="Eamsobhana2006"/> More research is needed because the life cycle is not completely known. Diagnosis is made by recovering the worms on bronchoscopy or oesophagogastroduodenoscopy. Due to the scant amount of information available on this parasite in literature, increased awareness is necessary, especially in endemic areas near ''M. laryngeus’'' reservoir hosts, for clinicians, the local population in the endemic area, and traveling tourists, to effectively recognize and prevent mammomonogamiasis.{{cn|date=January 2023}}

==Taxonomic classification==
[[Image:Syngamidae Taxonomy chart.JPG|thumb|Taxonomic family tree of ''Mammomonogamus'']]

''Mammomonogamus'' is classified in the family Syngamidae. The Syngamidae are in the superfamily Strongyloidae and order Strongylata, making them close relatives to hookworms and other nematodes.<ref name="Eamsobhana2006"/>

The generic name ''Mammomonogamus'' is derived from the Latin term {{Lang|la|mamma}} ('breast'), and the Greek terms {{Lang|grc-Latn|monos}} ({{Lang|grc|μόνος}} 'single') and {{Lang|grc-Latn|gamos}} ({{Lang|grc|γάμος}} 'marriage'),<ref name="deLara1993">de Lara, T. de A., Barbosa, M.A., de Oliveira, M.R., de Godoy, I., and Queluz, T.T. (1993). Human syngamosis: Two cases of chronic cough caused by Mammomonogamus laryngeus. ''Chest''. '''103'''(1): 264-5.</ref> which most likely is referring to the distinct characteristic of the male and female worm acting as a single unit through the male being joined in permanent copulation to the middle portion of the female's body.

Species within this genus are ''M. laryngeus'', ''M. nasicola'', ''M. gangguiensis'',<ref name="Nosanchuk1995"/> and ''[[Biology:Mammomonogamus auris|M. auris]]''.<ref>{{cite book|last1=Bowman|first1=Dwight D.|last2=Hendrix|first2=Charles M.|last3=Lindsay|first3=David S.|last4=Barr|first4=Stephen C.|title=Feline clinical parasitology|date=2001|publisher=John Wiley & Sons|location=Hoboken|isbn=9780470376591|pages=258–259|doi=10.1002/9780470376805}}</ref> Only ''M. laryngeus'' is known to infect and cause disease in humans.<ref name="Eamsobhana2006"/> Because of the close resemblance of ''M. laryngeus'' to the [[Biology:Gapeworm|gapeworm]] from the genus ''Syngamus'' that commonly infect birds, ''M. laryngeus'' was originally called ''Syngamus laryngeus'' and ''Syngamus kingi''.<ref name="Eamsobhana2006"/> The classification was revised in 1948 when Ryzhikov reconstructed the phylogenetic relationship of the family Syngamidae and recategorized the parasite as ''M. laryngeus''.<ref>{{cite journal| last=Ryzhikov | first=K. M. | year=1948 | title=[Phylogenetic interrelationships of nematodes of the family Syngamidae and an attempt to reconstruct their systematics] | journal=Doklady Akademii Nauk SSSR | volume=62 | page=733|language=ru}}</ref>

Infestation with ''M. laryngeus'' has been called mammomonogamiasis, mammomonogamosis, syngamosis', or 'syngamiasis.<ref>[http://web.gideononline.com/web/epidemiology], Mammomonogamiasis. GIDEON Infectious Diseases: Diseases. Accessed 5 Feb. 2009.</ref>

==History==

The parasite in this genus of greatest significance to humans is ''M. laryngeus'', due to the occasional, incidental cases reported in humans. While ''M. laryngeus'' commonly infects domestic ungulates and ruminants, the first reported case of a human infection was by Dr. King, who diagnosed the parasite in a woman from St. Lucia, Antilles.<ref name="Leiper1913"/> The next case originated in Brazil in the 1920s, where the connection with bovine species was confirmed.<ref>Freitas, A.L., De Carli, G., and Blankenhein, M.H. “Mammonomonogamus (Syngamus) laryngeus infection: a new Brazilian human case. ''Rev. Inst. Med. Trop. S. Paulo'', '''37''' (2): 177-179, 1995.</ref>

==Morphology==

The most distinct feature of ''M. laryngeus'' is the “Y” shape formed when the male is joined to the female ''in copula''.<ref name="Costa2005">[https://www.cdc.gov/eid] Costa, J.C., Delgado, M.L., Vieira, P., Afonso, A., Conde, B., and Cross, J.H (2005). Syngamoniasis in Tourist. ''Emerging Infectious Diseases''. '''Vol 11''', No. 12. .</ref> The smaller male uses its posterior bursa to attach to the female vulva located on the side near the middle of the female worm.<ref name="Gutierrez2000">Gutierrez, Yezid. Diagnostic Pathology of Parasitic Infections with Clinical Correlations. 2nd ed. New York: Oxford University Press, 2000.</ref> The adult worms usually remain permanently joined in this “Y” formation as they settle on the mucosal epithelium of the larynx, trachea, or bronchi.<ref name="Costa2005"/>

Adult ''M. laryngeus'' worms are red to reddish-brown in color due to their hemophagous nature.<ref name="Kim1998"/><ref name="deLara1993"/><ref name="Costa2005"/> They possess spicules ranging from 23-30 μm in length and cup-shaped buccal capsules (mouths) that open at the anterior end.<ref name="Nosanchuk1995"/><ref name="Costa2005"/><ref name="Gutierrez2000"/> Located deep in the buccal cavity are eight to 10 teeth that are not thought to be used for attachment.<ref name="Anderson1980"/>

The adult male is about half the length of the female. Case reports have found male worms ranging from 3–6.3&nbsp;mm in length and 360-380 μm in width. The larger females were reported to be 8.7-23.5&nbsp;mm long and 550-570 μm wide.<ref name="Nosanchuk1995"/><ref name="Costa2005"/> The female also has a pointed posterior end with a long or short tail. The female while ''in copula'' lays many ellipsoid-shaped eggs that are about 40 x 80 μm in size, not operculated, and usually possess thicker shells than hookworm eggs.<ref name="Kim1998"/><ref name="Gutierrez2000"/>

==Life cycle==
[[Image:Life cycle.JPG|thumb|Hypothesized lifecycle of ''Mammomonogamus laryngeus'']]

Although the complete lifecycle of ''M. laryngeus'' is not fully known due to the rareness of the parasite in humans, the parasite is thought to adopt a lifecycle similar to ''Syngamus trachea'',<ref name="Severo1988">Severo LC, Conci LMA, Camargo JJP, Andre-Alves MR, Palombini BC. Syngamosis: two new Brazilian cases and evidence of possible pulmonary cycle. ''Trans R Soc Trop Med Hyg.'' 1988;'''82''': 467–8.</ref> the common gapeworm infection in birds that was initially thought to be mammomonogamiasis. Currently, two existing hypotheses may help aid medical diagnostics, especially in endemic areas such as the tropics, the Caribbean, and Brazil.{{cn|date=January 2023}}

'''Hypothesis #1:'''
Infection initially begins by the ingestion of foods, water, or intermediate hosts contaminated by adult worms. The infective adults migrate to the larynx or trachea and attach to the mucosal walls. [[Biology:Sexual reproduction|Sexual reproduction]] occurs here, and the females begin to lay eggs in the upper respiratory region. Eggs do not develop at body temperature, and are expelled in sputum or reswallowed and excreted in feces.<ref name="Kim1998"/>

'''Hypothesis #2:'''
The infective agent may be embryonated eggs or infective larvae, and infection is due to ingestion of contaminated food, water, or intermediate hosts. As larvae are released into the intestinal area, they can burrow through intestinal walls, travel into the mesenteric veins, and migrate to the alveoli. Here, they undergo a pulmonary cycle, where the larvae develop into adult worms in a process that may take seven days. After reaching adulthood, ''M. laryngeus'' migrates upwards to the trachea, larynx, or bronchi, where sexual reproduction occurs. Egg production begins about three weeks later, and eggs are coughed up and expelled in sputum, or excreted in feces. Larvae may hatch from embryonated eggs outside of the mammalian host.<ref name="Kim1998"/><ref name="Acha2003">Acha PN, Szyfres B. Mammomonogamiasis. [[Biology:Zoonosis|Zoonosis]] and communicable diseases common to man and animals. Washington (DC): ''Pan American Health Organization''; 2003. Scientific and Technical Publication No. 580.</ref>

More research is needed to fully elucidate the lifecycle, but both larvae and adults appear to be infective. One recent case reported finding adult worms in the [[Biology:Duodenum|duodenum]],<ref name="Eamsobhana2006"/> which is the first presentation of adult worms not in the upper respiratory region. The adult worms might have been coughed up and reswallowed before settling in the duodenum. The development from larvae to adults is about three weeks,<ref name="Weinstein1971"/> but the existence of a larval pulmonary cycle is uncertain. Intermediate hosts, although not fully known, may be earthworms (an intermediate host for the genus ''Syngamus''),<ref name="Gutierrez2000"/> snails, or arthropods.<ref name="Costa2005"/> Other than intermediate hosts, no mention of other biological or mechanical [[Biology:Vector (epidemiology)|vectors]] has been made.

==Symptoms of infection in humans==

Symptoms usually began to appear six to 11 days after initial infection, beginning with a fever and cough. Most cases reported a progression to a persistent cough, leading to expectoration and sometimes [[Medicine:Hemoptysis|hemoptysis]].<ref name="Nosanchuk1995"/><ref name="Costa2005"/> Worms in the bronchial region can trigger a chronic, nonproductive cough and asthma-like symptoms due to the obstruction of airways by the worms.<ref name="Nosanchuk1995"/><ref name="deLara1993"/><ref name="Severo1988"/> These symptoms, along with a low-grade fever, can last several months if not initially diagnosed correctly. A scratching or crawling sensation can be felt in the throat if the worms are attached in the larynx.<ref name="Weinstein1971"/><ref name="Costa2005"/><ref name="Severo1988"/> Weight loss<ref name="Birrell1978">Birrell, D.J., Moorhouse, D.E., Gardnert, M.A.H., and May, C.S (1978). Chronic Cough and Haemoptysis due to a Nematode, "Syngamus Laryngeus." '''Aust. N.Z. J. Med.''' '''8''': 168-170.</ref> and [[Medicine:Pneumonitis|pneumonitis]]<ref name="Severo1988"/> have been reported as possible long-term consequences, but not [[Medicine:Anemia|anemia]].

Recently, ''M. laryngeus'' worms were found in the duodenum of a Thai patient, which was the first gastrointestinal case of ammomonogamiasis. The patient complained of chest pain, haematemesia, melaena, and abdominal bloating, but no respiratory symptoms. Although nothing conclusive was determined, the adult worms perhaps were dislodged from the larynx, reswallowed, and later found in the duodenum.<ref name="Eamsobhana2006"/>

==Pathogenesis==

Little is known about how ''M. laryngeus'' causes disease. Symptoms do not arise until the worms have reached the adult stage and obstruct the bronchial airways leading to asthma-like symptoms and coughing.<ref name="Weinstein1971"/> Similar symptoms are seen in humans, as well as the domestic ungulates and ruminant hosts. Bronchial inflammation or hemotypsis may occur due to the worms attaching to the mucosal walls and ingesting red blood cells.<ref name="Costa2005"/>

The incubation period is usually six to 11 days after infection.<ref name="Weinstein1971"/> This supports the second hypothesis of a possible pulmonary cycle that explains the one- to two-week delay in the presentation of symptoms.{{cn|date=January 2023}}

Eosinophilia is not a reliable measure of extent of infection because it varies from individual to individual. Some cases with multiple pairs of worms have reported low [[Biology:Eosinophil|eosinophil]] levels, while other cases with a single pair had very high eosinophil counts. Such variation may be due to the lack of host tissue invasion by the parasite, since ''M. laryngeus'' attaches to the mucosal [[Biology:Epithelium|epithelium]] in the tracheolaryngeal region.<ref name="Nosanchuk1995"/> A singular case even found worms within a cyst.<ref name="Gardiner1983">Gardiner, C.H. and Schantz, P.M (1983). Mammomonogamus Infection in A Human: Report of A Case. ''Am. J. Trop. Med. Hyg.'' '''32'''(5) 995-997.</ref>

Past cases have demonstrated that simple removal of the worms from upper respiratory area led to a cessation of symptoms and was a sufficient cure with or without antihelmintics.<ref name="Nosanchuk1995"/><ref name="Costa2005"/> No lasting pathological tissue damage was reported.

Thus far, no reinfection mechanism for ''M. laryngeus'' has been posited, so all adult worms found inside a human must be the result of ingested embryonated eggs, larvae, or adult worms. Most of the time, only one pair of worms is found, but occasionally, the patient may have multiple pairs that must all be removed.<ref name="Nosanchuk1995"/><ref name="Pipitogool1992">Pipitogool V, Chaisiri K, Visetsuspakarn P, Srigan V, Maleewong W. Mammomonogamus (syngamus) laryngeus. First case report in Thailand. ''Southeast Asian J Trop Med Public Health''. 1992;'''23''':336–7.</ref>

==Diagnosis==

The definitive diagnosis is the recovery of adult worms either by coughing them up<ref name="deLara1993"/> or removing them with [[Engineering:Forceps|forceps]], a bronchoscope, or endoscopic instruments. However, worms might be difficult to remove if firmly attached to the bronchial walls.<ref name="Kim1998"/> Finding ''M. laryngeus'' eggs in the sputum or feces<ref name="Nosanchuk1995"/><ref name="Costa2005"/> is another sure sign of infection.

The eggs closely resemble hookworm eggs, but ''Mammomonogamus'' eggs have a much thicker shell.<ref name="Gutierrez2000"/>

==Treatment==

Mammomonogamiasis is relatively easy to treat. Manual or bronchoscopic removal of worms has been successful.<ref name="Costa2005"/> One case followed up with aspiration.<ref name="Kim1998"/> Although no controlled study on the efficacy of antihelmintics in treating mammomonogamiasis has been conducted, most patients were given [[Chemistry:Albendazole|albendazole]], [[Chemistry:Mebendazole|mebendazole]] or thiabendazole with no adverse effects. Patients given albendazole were instructed to take 400&nbsp;mg for three days<ref name="Kim1998"/> or if given a combination of drugs, albendazole is given 200&nbsp;mg, three times a day for three days, with mebendazole at 100&nbsp;mg, three times a day for three days.<ref name="Costa2005"/> The drug regimens ranged from 200–3000&nbsp;mg/day for three to 20 days.<ref name="Nosanchuk1995"/>

==Epidemiology==

Mammomonogamiasis is a very rare human infection yet a common veterinary parasite. Only 100 human cases of ''M. laryngeus'' have been reported, thus far.<ref name="Nosanchuk1995"/> Its reservoir hosts are largely in tropical regions, most commonly the domestic cattle,<ref>Van Aken, D., Lagapa, J.T., Dargantes, A.P., Vercruysse, J., 1996. Mammomonogamus laryngeus (Railliet, 1899) infections in cattle in Mindanao. Philippines. ''Vet. Parasitol.'' '''64''', 329—332.</ref> cats,<ref name="Anderson1980"/> orangutans,<ref name="Collet1986">Collet, J.Y., Galdikas, B.M., Sugarjito, J., Jojosudharmo, S., 1986. A coprological study of parasitism in orangutans (Pongo pygmaeus) in Indonesia. ''J. Med. Primatol''. '''15''', 121—129.</ref> and other ruminants and ungulates. Therefore, humans are accidental hosts,<ref name="Costa2005"/> where infections are most likely to due close exposure to bovine or feline species.{{cn|date=January 2023}}

While the complete life cycle is still not fully known, transmission is thought to be oral-fecal, where infection comes from ingesting contaminated food or water containing embryonated eggs, hatched larvae, or intermediate hosts. Possible intermediate host candidates include earthworms, snails, and arthropods.<ref name="Costa2005"/> Eggs are expelled in sputum or feces. Most often, travelers to tropical climate places become exposed to contaminated sources and are diagnosed upon return to their country. The best preventative measure is to ensure proper food preparation and water sanitation.

From the numerous case reports, endemic areas include Martinique, Brazil, Puerto Rico, Dominica, Santa Lucia, Trinidad, Guyana, Guadeloupe,<ref name="Gutierrez2000"/> India, tropic regions in Africa, Malaysia,<ref name="Pipitogool1992"/> the Philippines,<ref name="StJohn1929"/><ref name="Beaver1984">Beaver PC, Jung RC, Wayne E. Clinical parasitology. Philadelphia: ''Lea and Febiger;'' 1984.</ref> Vietnam,<ref name="Acha2003"/> China,<ref>Li D, Li G, Zhan X (1997). Three cases of human Mammomonogamus laryngeus infection. ''Chin J Parasitol Parasit Dis'' '''15''': 281–4.</ref><ref>Qu, F.Y., 1997. First Mammomonogamus laryngeus infection case occurred in Shanghai. ''Chin. J. Parasitol. Parasit. Dis.'' '''15''', 198—200</ref> Korea,<ref name="Kim1998"/> and Thailand.<ref name="Eamsobhana2006"/><ref name="Pipitogool1992"/><ref>Limawongpranee, S., Samanthai, S., Yoolek, A., 2004. Human Mammomonogamus laryngeus infection (syngamosis): the second case report in Thailand. ''Siriraj Hosp. Gaz.'' '''56''', 82—86.</ref>

Due to the frequency of travelers contracting this disease, countries such as Australia,<ref name="Birrell1978"/> Canada,<ref>Leers, W.-D., M. K. Sarin, and K. Arthurs. 1985. Syngamosis, an unusual cause of asthma: the first reported case in Canada. ''Can. Med. Assoc. J.'' '''132''':269–270.</ref> United States,<ref name="Nosanchuk1995"/><ref name="Weinstein1971"/><ref name="Gardiner1983"/> UK,<ref>Basden, R. D. E., J. W. Jackson, and E. I. Jones. 1974. Gapeworm infestation in man. ''Br. J. Dis. Chest'' '''68''':207–209.</ref><ref name="Turner P 2003">Turner P, Turner CG, Bowers KM, Gibson DI, Chiodini PL (2003). A Case of Human Syngamosis. ''Travel Med Infect Dis.'' '''1'''(4): 231-3.</ref> France<ref>Junod, C., M. Philbert, and H. T. Sang. 1970. Une observation de syngamose humaine a localization bronchique. Premier cas tracte et queri par le thiabendazole. ''Bull. Soc. Pathol. Exot.'' '''63''':483–488.</ref><ref>Sang, H. T., C. Junod, and M. Philbert. 1970. Notes parasitologiques sur Syngamus laryngeus Railliet, 1899 et la syngamose humaine. A propos d’un cas de syngamose bronchique chez l’homme. ''Bull. Soc. Pathol. Exot.'' '''63''':488–497.</ref> have reported cases, although these countries are not considered to be endemic for the parasite.

== Public health ==
Mammomonogamiasis is not considered an emerging disease<ref name="Costa2005"/> because of the rarity of cases. Consequently, no control measures are currently being implemented. Very little information about this disease can be found in literature, so physicians especially in endemic areas should be aware of the parasitic disease, the clinical presentations, and treatment for humans.<ref name="Eamsobhana2006"/>

== References ==
{{Reflist|30em}}

== External links ==
* [https://www.cdc.gov/ncidod/eid/vol11no12/05-0713.htm Information] from the Centers for Disease Control and Prevention.

{{Taxonbar|from=Q6745836}}

[[Category:Strongylida]]
[[Category:Zoonoses]]

{{Sourceattribution|Mammomonogamus}}