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Strongyloides planiceps Rogers, 1943

SYNONYMS: Strongyloides cati Rogers, 1939

ETYMOLOGY: Strongyl = round and oides = like for the genus and planiceps for the species name of the Rusty tiger cat, Felis planiceps, the host from which the parasite was isolated by R. T. Leiper in 1927.

GEOGRAPHIC DISTRIBUTION: Strongyloides planiceps was originally described from Malaya (Rogers, 1943) and subsequent found in wild carnivores and occasionally domestic cats in Japan (Horie et al., 1981; Fukase et al., 1985). It has been observed several times in cats from Japan. It has not been observed in the United States.

LOCATION IN HOST:Strongyloides planiceps is present in the anterior portion of the small intestine.

IDENTIFICATION: Parasitic females are 2.4-3.3 mm long (mean, 2.8 mm); the ovaries of the female have a spiral appearance. Partially embryonated eggs measuring 58-64 by 32-40 µm (mean, 61 by 35 µm) are excreted in the feces. Infections with Strongyloides planiceps can be identified by finding embryonated eggs in fecal smears or fecal flotations. Fresh samples should examined to avoid confusion with hookworm eggs. The tip of the tail of the parasitic female of Strongyloidesplaniceps abruptly narrows to a blunt end, while that of Strongyloidesfelis is longer and narrows more slowly to the tip of the tail (Horie et al., 1981).

LIFE CYCLE: Cats become infected by oral ingestion of infective larvae or by skin penetration (Rogers, 1939). Larvae can be found in the lungs by four days after infection, and young parthenogenic adult females can be found in the small intestine 6 days after skin penetration. Eggs are excreted in the feces 10 to 11 days after infection.

CLINICAL PRESENTATION AND PATHOGENESIS: There has been no description of clinical signs in infected cats. It is possible that large numbers are capable of causing disease, but this is likely to require careful research in which this species is examined in cats known to be free of other helminths, particularly, Strongyloidesfelis.

TREATMENT: This is likely to be similar to that reported for Strongyloidesfelis. It is expected that therapeutic doses of ivermectin may also be efficacious.

EPIZOOTIOLOGY: This parasite is probably as common in its range in dogs as it is in cats (Fukase et al., (1985). These authors report finding this parasite in 4 of 420 dogs, 4 of 105 domestic cats, 26 of 40 raccoon dogs (Nyctereutesprocyonoidesviverrinus) and 2 of 5 Japanese weasels (Mustelasibiricaitatsi). Cats can become infected either by the oral inoculation of larvae or by skin penetration, and it would appear that where the range of cats overlaps that of wildlife reservoir hosts that cats will be at risk of infection with this parasite.

HAZARD TO HUMANS: There are no records of this parasite in humans.

HAZARD TO OTHER ANIMALS:Strongyloides planiceps is found in wildlife in areas of the world where it is present. It has been reported from dogs, raccoon dogs, Japanese weasels, and the rusty tiger cat in Malaysia. It appears that a red fox from Hokkaido Japan was also infected with this parasite (Fukase et al., 1985).


Fukase T, Chinone S, Itagaki H. 1985. Strongyloides planiceps (Nematoda; Strongyloididae) in some wild carnivores. Jpn. J. Vet. Sci. 47:627-632.

Horie M, Noda R, Higashino J. 1981. Studies on Strongyloides sp. isolated from a cat and raccoon dog. Jpn. J. Parasitol. 30: 215-230.

Rogers WP. 1939. A new species of Strongyloides from the cat. J. Helminthol. 17: 229-238.

Rogers WP. 1943. Strongyloidesplaniceps, new name for S. cati Rogers. J. Parasitol. 29: 160.