''Linguatula serrata'' is a species of

cosmopolitan Cosmopolitan may refer to: Internationalism * World citizen, one who eschews traditional geopolitical divisions derived from national citizenship * Cosmopolitanism, the idea that all of humanity belongs to a single moral community * Cosmopolitan ...

zoonotic A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a virus, bacterium, parasite, fungi, or prion) that can jump from a non-human vertebrate to a human. When h ...

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

, belonging to the tongueworm order

Pentastomida The Pentastomida are an enigmatic group of parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus ''Linguatula'' to a vertebrate tongue; molecular studies point to them being highly derived crust ...

. They are wormlike parasites of the respiratory systems of vertebrates. They live in the nasopharyngeal region of

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

Cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers. ...

s, foxes, and other

carnivores A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

are normal hosts of this parasite. Apparently, almost any mammal is a potential

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include ...

Description

The adult parasite is dorsoventrally flattened, tapering backwards, resembling a vertebrate tongue thus, inspiring the common name of "tongueworm". Physical characteristics; males: in length, while the females are .

Distribution

''L. serrata'' can be found worldwide but especially in warm subtropical and temperate regions.

Behavior and ecology

Life cycle

Adult ''L. serrata'' embeds their forebody into the nasopharyngeal mucosa, feeding on blood and fluids. Females live at least two years and produce millions of eggs. Eggs exit the host in nasal secretion or, if swallowed with feces. When swallowed by an intermediate host, the four-legged larvae (resembling a mite) hatch in the small intestine, penetrate the intestinal wall, and lodge in tissues, particularly in lungs, liver, and lymph nodes. The nymphal stage develops. When eaten by a definitive host, infective nymphs either attach in the upper digestive tract or quickly travel there from the stomach, reaching the

nasopharynx The pharynx (: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its ...

. Females begin egg production in about six months.

Reproduction

Both male and females are required to mate for successful reproduction. Males choose to mate with females that are close to their own size. Females contain hundreds of thousands of eggs.

Disease

Linguatulosis is a condition associated with the organism ''Linguatula serrata''. More generally, linguatulosis can be considered a form of "pentastomiasis", which refers to all diseases caused by

pentastomid The Pentastomida are an enigmatic group of parasite, parasitic arthropods commonly known as tongue worms due to the resemblance of the species of the genus ''Linguatula'' to a vertebrate tongue; molecular studies point to them being highly deri ...

s, including porocephaliasis. This disease is often accidentally identified during

autopsy An autopsy (also referred to as post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of deat ...

because of its asymptomatic effect on the body.

Epidemiology

Among ''Linguatula serrata'' infecting Cairo street dogs, 10% were juveniles, 59% were males, and 31% were females, corresponding to a sex ratio of 1.9:1. Of all infections, 67% were found during spring and summer, compared to 33% during fall and winter. The probable source of canine infections is infected lymph nodes of cattle, sheep, goats, and/or camels, which produce the symptoms of halzoun and the marrara syndrome in man when consumed raw.

References

{{Authority control Parasitic crustaceans Cosmopolitan arthropods Crustaceans described in 1789 Taxa named by Josef Aloys Frölich