Title: Paragonimus

{{Short description|Genus of flukes}}
{{Automatic taxobox
| image = Paragonimus westermani 01.jpg
| image_caption = Egg of ''[[Paragonimus westermani]]''
| display_parents = 3
| parent_authority = [[Robert-Philippe Dollfus|Dollfus]], 1939
| taxon = Paragonimus
| authority = Braun, 1899&amp;nbsp;&lt;ref&gt;{{cite journal |author=M. Braun |year=1899 |title=Über ''Clinostomum'' Leidy |journal=[[Zoologischer Anzeiger]] |volume=22 |issue=603 |pages=489–493 |url=https://www.biodiversitylibrary.org/ia/zoologischeranze221899caru#page/512/mode/1up}}&lt;/ref&gt;
| subdivision =
* ''[[Paragonimus africanus]]''
* ''[[Paragonimus caliensis]]''
* ''[[Paragonimus compactus]]''
* ''[[Paragonimus ecuadoriensis]]''
* ''[[Paragonimus heterotremus]]''
* ''[[Paragonimus hueitugensis]]''
* ''[[Paragonimus ichunensis]]''
* ''[[Paragonimus iloktsuenensis]]''
* ''[[Paragonimus kellicotti]]''
* ''[[Paragonimus mexicanus]]''
* ''[[Paragonimus miyazakii]]''
* ''[[Paragonimus ohirai]]''
* ''[[Paragonimus pulmonalis]]''
* ''[[Paragonimus peruvianus]]''
* ''[[Paragonimus sadoensis]]''
* ''[[Paragonimus skrjabini]]''&lt;ref name=&quot;Davis 1994&quot;/&gt;
* ''[[Paragonimus uterobilateralis]]''
* ''[[Paragonimus westermani]]''
}}

'''''Paragonimus''''' is a [[genus]] of flukes ([[trematode]]s) and is the only genus in the [[monotypic]] family '''Paragonimidae'''. Some tens of species have been described, but they are difficult to distinguish, so it is not clear how many of the named species may be [[Synonym (taxonomy)|synonym]]s. The name Paragonimus is derived from the combination of two Greek words, “para” (on the side of) and “gonimos” (gonads or genitalia).&lt;ref name=&quot;Procop 2009&quot;&gt;{{cite journal |author1=G. W. Procop |year=2009 |title=North American Paragonimiasis (caused by ''Paragonimus kellicotti'') in the Context of Global Paragonimiasis |journal=[[Clinical Microbiology Reviews]] |volume=22 |issue=3 |pages=415–446 |pmid=19597007 |doi=10.1128/cmr.00005-08|pmc=2708389 }}&lt;/ref&gt; Several of the species are known as '''lung flukes'''. In humans some of the species occur as [[Zoonosis|zoonoses]]; the term for the condition is [[paragonimiasis]]. The first [[intermediate host]]s of ''Paragonimus'' include at least 54 species of [[freshwater snail]]s from superfamilies [[Cerithioidea]] and [[Rissooidea]].&lt;ref name=&quot;Davis 1994&quot;&gt;{{cite journal |author1=G. M. Davis |author2=C. E. Chen |author3=Z. B. Kang |author4=Y. Y. Liu |year=1994 |title=Snail hosts of ''Paragonimus'' in Asia and the Americas |journal=Biomedical and Environmental Sciences |volume=7 |issue=4 |pages=369–382 |pmid=7535537}}&lt;/ref&gt;

The most prominent species of ''Paragonimus'' in human medicine is ''[[Paragonimus westermani]]'', an infectious lung fluke originating in eastern Asia. Worldwide, about nine species of ''Paragonimus'' are known to cause human paragonimiasis in which many of the species reside in East Asia, West Africa, and in North and South America.&lt;ref name=&quot;Procop0&quot; /&gt;

== Morphology ==
[[File:Paragonimus westermani adult.jpg|thumb|Morphology of typical ''Paragonimus'': &lt;br /&gt;
'''AC''': acetabulum (ventral sucker)&lt;br /&gt;
'''CE''': cecum, '''EB''': excretory bladder&lt;br /&gt;
'''OS''': oral sucker, '''OV''': ovary&lt;br /&gt;
'''TE''': testes, '''UT''': uterus ]]
Species of ''Paragonimus'' vary in size; the adult stage might attain a length of up to {{convert|15|mm}} and a width of up to {{convert|8|mm|abbr=on}}.&lt;ref name=&quot; Vélez 2003&quot;&gt;{{Cite journal |author=Imelda Vélez, Luz E. Velásquez and Iván D. Vélez |year=2003 |title=Morphological description and life cycle of ''Paragonimus'' sp. (Trematoda: Troglotrematidae): causal agent of human paragonimiasis in Colombia |journal=[[Journal of Parasitology]] |volume=89 |issue=4 |pages=749–755 |pmid=14533686 |jstor=3285872 |doi=10.1645/ge-2858|s2cid=8120364 }}&lt;/ref&gt; The adult flatworm has an oval shape body with spines covering its thick tegument. Both the [[oral sucker]] and [[Acetabulum (morphology)|acetabulum]] are round and muscular. The acetabulum is slightly bigger than the oral sucker – 0.19&amp;nbsp;mm and 0.12&amp;nbsp;mm, respectively.&lt;ref name=&quot; Vélez 2003&quot; /&gt; [[Ovary|Ovaries]] are located behind the acetabulum and posterior to the ovary are the [[testes]]. The [[seminal receptacle]], the [[uterus]] and its metraterm, the thick-walled terminal part, lie between the acetabulum and the ovary.&lt;ref name=&quot; Vélez 2003&quot; /&gt;

== Life cycle ==
The parasite passes through two [[intermediate host]]s, an [[aquatic snail]] and a [[crustacean]]. It enters its [[mammal]]ian [[definitive host]]s when they eat infected freshwater crustaceans. Typical hosts include dogs, cats, and humans. Humans usually contract paragonimiasis when they eat undercooked [[freshwater crab]]s (for instance species of the genus ''[[Nanhaipotamon]]'') or [[crayfish]], that contain live [[Trematode lifecycle stages|metacercariae]]. In the intestine, the parasite will move into the abdomen and commonly into the lungs. In the lung, the parasites encyst and cross fertilize each other. The cyst eventually ruptures in the lungs and the eggs may be coughed up or swallowed and excreted in the feces. An egg landing in fresh water hatches and releases a ciliated miracidium. A successful miracidium swims about until it finds an intermediate host, usually an aquatic snail. A crustacean in turn becomes infected by eating infected snails. The definitive host completes the cycle if it eats infected crustaceans.{{citation needed|date=January 2023}}

== Epidemiology ==
Worldwide roughly 20 million people are infected with ''Paragonimus''. Human infections are most common in regions with many human and animal reservoir hosts plus an abundance of intermediate hosts, such as snails, crabs, or crayfish, and where in addition consumption of raw or undercooked seafood is common. Consumption of insufficiently cooked meat from infected land animal hosts, such as wild boar, commonly transmits the infection.&lt;ref&gt;{{cite web|title=Paragonimiasis|url=http://www.uptodate.com/contents/paragonimiasis?source=machineLearning&amp;search=Paragonimus&amp;selectedTitle=1%7E18&amp;sectionRank=4&amp;anchor=H2#H2|publisher=UpToDate|access-date=15 May 2014|author=Karin Leder|author2=Peter F Weller|archive-url=https://web.archive.org/web/20160821174555/http://www.uptodate.com/contents/paragonimiasis?source=machineLearning&amp;search=Paragonimus&amp;selectedTitle=1%7E18&amp;sectionRank=4&amp;anchor=H2#H2|archive-date=21 August 2016|url-status=dead}}&lt;/ref&gt; The domestic cat is a reservoir for a variety of lung flatworms and can [[Feline zoonosis|transmit the infection to humans]].

== Symptoms ==
[[Symptom]]s of paragonimiasis may include [[abdominal pain]], [[diarrhea]], [[fever]], and [[hives]]. If the infection remains untreated, the symptoms may diminish or disappear after only few months, but sometimes they last for decades.&lt;ref&gt;{{cite web|title=Paragonimiasis (lung fluke)|url=http://www.ochealthinfo.com/docs/public/epi/paragfactsheet.pdf|access-date=8 December 2011|date=August 2006|url-status=dead|archive-url=https://web.archive.org/web/20111211210130/http://ochealthinfo.com/docs/public/epi/paragfactsheet.pdf|archive-date=11 December 2011}}&lt;/ref&gt; Paragonimiasis is caused by the body's natural [[immune response]] to the worms and eggs that are present and also migrating from the intestines to the lungs.{{citation needed|date=January 2023}}

As a rule, the parasites begin to cause symptoms about three weeks after ingesting live metacercariae. After about eight weeks, they begin to produce eggs in the lungs. Some patients develop brain damage if parasites establish in the brain and produce eggs. The brain damage commonly causes [[headache]], [[vomiting]], and [[seizure]]s.&lt;ref name=&quot;Procop0&quot;&gt;{{cite journal |author=Gary W. Procop |year=2009 |title=North American paragonimiasis (caused by ''Paragonimus kellicotti'') in the context of global paragonimiasis |journal=[[Clinical Microbiology Reviews]] |volume=22 |issue=3 |pages=415–446 |doi=10.1128/CMR.00005-08 |pmid=19597007 |pmc=2708389}}&lt;/ref&gt; Untreated cerebral paragonimaisis commonly results in death from increased intracranial pressure.

== Treatment ==
[[Praziquantel]] has been used to effectively treat paragonimiasis by separating the tegument. An effectively complete rate of cure may be expected after three days of treatment if there has not been too much permanent damage, such as from intracranial effects.&lt;ref name=&quot;Yukifumi&quot;&gt;{{cite journal |author=Nawa Yukifumi |year=2000 |title=Re-emergence of paragonimiasis |journal=[[Internal Medicine (journal)|Internal Medicine]] |volume=39 |issue=5 |pages=353–354 |doi=10.2169/internalmedicine.39.353 |pmid=10830172|doi-access=free }}&lt;/ref&gt; Other medications can also be used such as [[bithionol]], [[niclofan]], and [[triclabendazole]] with high cure rates.{{citation needed|date=January 2023}}

== Prevention ==
Thorough cooking of an infected crustacean kills all stages of the parasite. Crab meat should not be eaten raw, even if pickled, because the pickling solution often fails to kill all the parasites. Utensils and cutlery boards should be cleaned thoroughly before and after food preparation.&lt;ref name=Procop0 /&gt;

== References ==
{{Reflist|32em}}

{{Taxonbar|from1=Q2349904|from2=Q15260052}}
{{Authority control}}

[[Category:Plagiorchiida genera]]
[[Category:Cat diseases]]
[[Category:Zoonotic parasitic diseases]]
[[Category:Plagiorchiida]]