Linguatula serrata is a cosmopolitan zoonotic parasite, belonging to the Pentastomida, also known as tongue worms. They are wormlike parasites of the respiratory systems of vertebrates. They live in the nasopharyngeal region of mammals. Cats, dogs, foxes, and other carnivores are normal hosts of this parasite. Apparently, almost any mammal is a potential intermediate host.
The adult parasite is dorsoventrally flattened, tapering backwards resembling a vertebrate tongue, originating its name from it.
Physical characteristics: males: 18–20 millimetres (0.71–0.79 in) in length, while the females are 80–120 mm (3.1–4.7 in).
Behavior and 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.
Infection of Cairo dogs varies from male to female, with a ratio of 1.9:1 (58.97% and 30.77%, respectively). Prevalence of infection rate is higher during spring and summer (66.67%), compared during fall and winter, which constitutes 33.33% of the infection rate. 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 .
Geographic range 
L.serrata can be found worldwide but especially in warm subtropical and temperate regions.
Life cycle 
Adult L. serrata embed 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. Females begin egg production in about six months.