Cylicospirura subaequalis

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Cylicospirura subaequalis (Molin, 1860) Vevers, 1922

ETYMOLOGY:Spiro = coiled and cerca = tail, along with subaequalis referring to the spicules of different lengths.

SYNONYMS:Spiropterasubaequalis Molin, 1860.

HISTORY: In 1860, Molin described Spiropterasubaequalis from specimens collected from cats in South America and Algeria. In 1913, Seurat described specimens from cats in Algeria. In 1922, Vevers created the genus Cylicospirura to include specimens recovered from animals in the London Zoo.

GEOGRAPHIC LOCATION: Reports of this species in cats have come from India (Alwar and Mudaliar, 1947; Alwar and Lalitha, 1958; Abdul Rahman et al., 1971; Pillai et al., 1981; and Siliban et al., 1996). Molin (1860) had originally described this parasite from cats in South America and Algeria. Seurat (1913) reported on the recovery of this worm from tumors in the stomach of Felisocreata in Algeria and from Felisconcolor and Felismellivora from Brazil. In 1988, Waid and Pence redescribed Cylicospirurasubaequalis from the America cougar (Felisconcolor).

LOCATION IN HOST: The adults of Cylicospirurasubaequalis are found in cysts or tumors located in the wall of the fundus of the stomach. Waid and Pence (1988) found that in mountain lions the worms and nodules were mainly in the duodenum near the pyloric sphincter.

PARASITE IDENTIFICATION: These are reddish-brown worms. The female is 22 mm long, and the male is 20 mm long. The esophagus is about 20% of the total body length, and the vulva is located slightly anterior to the esophageal-intestinal junction. The spicules in the male are unequal with the left spicule being about 2.5 mm long and the right spcule being about 0.5 mm long. The feature that differentiates Cyclicospirurasubaequalis from the other species of Cyclicospirura is the shape of the anterior ends of the longitudinal ribs of the buccal capsule when viewed en face (Clark, 1981). These ribs in the case of Cylicospirurasubaequalis are bifid at their anteriormost projection Females of Cylicospirurasubaequalis can be differentiated from females of Cylicospirura felineus by the position of the vulva relative to the esophago-intestinal junction. In Cylicospirurasubaequalis, the vulva is located posterior to this junction; in Cylicospirurafelineus, it is anteriad to this junction (Waid and Pence, 1988).

LIFE CYCLE: The life has not been described for any member of this genus. Based on affinities it morphologically related forms, it is postulated that the intermediate host would be an arthropod, probably a beetle. There is also a possibility that vertebrate paratenic hosts are involved in the life cycle.

CLINICAL PRESENTATION AND PATHOGENESIS: There have been no reports actually detailing the clinical signs associated with infections with this parasite. The lesions would suggest clinical signs, but they have not yet been described.

Abdul Rahman et al. (1971) described the histopathology associated with a 4 cm nodule from the stomach of a cat in Bangalore, India. A single reddish brown worm was seen grossly protruding from the lesion, and dissection revealed a second worm within the nodule. Histopathology revealed that the nodule represented chronic inflammatory proliferation of connective tissue with suppuration around the contained worms. The lesions in the duodenum of the lions described by Waid and Pence (1988) were typically 1.5 to 2.5 cm in diameter, each with a central opening on the serosal surface. The nodules contained a necrotic cavity surrounded by fibrous encapsulation. The necrotic cavities contained debris, partially calcified remains of nematodes, and intact immature and adult nematodes.

TREATMENT: Not reported.

EPIZOOTIOLOGY: This parasite is probably found in various wild felids and occasionally makes its way into the domestic cat. In North America, the potential wild hosts include mainly the lynx, bobcat, and puma, and it is unclear to what extent these populations overlap with the majority of domestic cats in the United Stated.

HAZARDS TO OTHER ANIMALS: Due to the requirement for an intermediate host, it is unlikely that these parasites would be directly transmitted from one cat to another or directly to other animals they may be living with while infected.

HAZARD TO HUMANS: There have been human infections with this parasite reported.

CONTROL/PREVENTION: Cats that hunt are likely to be those that become infected.


Abdul Rahman, Hegde KS, Mohiyudeen S, Seshjadri SJ, Rahamathulla PM, Rajasekharan D. 1971. Study of Cylicospirura subaequalis (Molin, 1860) and the histopathology of the nodule in the sromach of the cat. Ind Vet J 48:683-687.

Bhalerao GD. 1935. Helminth parasites of domesticated animals in India. Sci Mong 6, Imper Counc Agric Res, Delhi, India

Clark WC. 1981. Cylicospiruraadvena n. sp. (Nematoda: Spirocercidae) a stomach parasite from a cat in New Zealand, with observations on related speceis. Systematic Parasitol 3:185-191.

Molin R. 1860. Una mongragia del genere Spiroptera. Sitzungsb K Akad Wissensch Wien, Math Naturw CL 38(28)7-38, 1 plate. [not sure might be pages 911-1005, may also be issue 23 rather than issue 28, SORRY].

Pillai KM, Pythal C, Sundara RK. 1981. A note on the occurrence of Cylicospirurasubaequalis (Molin, 1860) (Spiruridae: Nematoda) in a jungle kitten (Felis chaus) in Kerala. Kerrala J Vet Sci 12:155-156.

Rickard LG, Foreyt WJ. 1992. Gastrointestinal parasites of cougars (Felisconcolor) in Washington and the first report of Ollulanus tricuspis in a sylvatic felid from North America. J Wildl Dis 28:130-133.

Seurat LG. 1913. Sur deux spiroptères du chat ganté (Felisocreata Gmel.). Compt Rend Soc Biol, Paris 74:676-679.

Silamban S, Ramachandran KM, Devi TL, Pillai KM. 1996. Histopathology of Cylicospirurasubaequalis induced nodule (Molin, 1860) in the stomach of a cat. J Vet Anim Sci. 27:68-69.

Waid DD, Pence DB. 1988. Helminths of moutain lions (Felisconcolor) from southwestern Texas, with a redescription of Cylicospirurasubaequalis (Molin, 1860) Vevers, 1922. Can J Zool 66:2110-2117.

Vevers GM. 1922. On the parasitic nematoda collected from mammalian hosts which died in the gardens of the Zoological Society of London during the years 1919-1921; with a description of three new genera and three new species. Proc Zool Soc London (1922) part 4:901-919.

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