Trichurisfelis (Diesing, 1851) Diaz-Ungria, 1963)
ETYMOLOGY: The genus name Trichuris, which may be translated as "hair tail," is actually a misnomer. A more appropriate name is Trichocephalus or Trichocephalos ("hair head"), nomenclature that is employed in Russia and in certain countries of eastern Europe.
SYNONYMS: See history.
HISTORY: In 1851, Diesing described a species of Trichocephalus (Trichuris) from a tiger-cat in Brazil. He named the parasite Trichocephalusfelis; however, the only description that he gave was that it was about 2 cm in length. Almost all other authors either ignore this species or regard it as differing from the trichurid of the domestic cat. Two species of Trichuris, Trichuriscampanula and Trichurisserrata, were described from the domestic cat in Brazil by von Linstow in 1879 and 1889, respectively. In the case of T. campanula, no complete male worm was recovered. In 1923 Urioste, a Brazilian, concluded that T. serrata was the only valid species; however, Baylis pointed out that there were considerable discrepancies between von Linstow's measurements of T. serrata and those of Urioste. Urioste's measurements agreed very closely with the original description of T. campanula. Urioste included a complete description of the male worm (Clarkson and Owen, 1960). Dias-Ungria , after finding worms in a Felis tigrina in Venezuela compared what had been described up to this point in time. Until the worms are better described, there seems to be no reason not to give the name Trichurisfelis priority. Arenas et al. collected T. serrata from Cuba in 1934, and Vogelsang reported the infrequent finding of T. campanula in Venezuela (Enzie, 1951).
More recently, reports of adult feline whipworms have been made in Australia (Holmes and Kelly, 1972, Kelly, 1973, Ng and Kelly, 1975a). Whenever others have reported finding eggs of Trichuris in the feces of cats in various localities throughout the world, it is highly probable that these reports were due to mistaken identification of capillarid eggs (Enzie, 1951).
GEOGRAPHIC DISTRIBUTION: The feline whipworm is an extremely rare parasite, demonstrating a diverse geographic range. Sporadic reports of feline trichuriasis have been made from across the United States (Lillis, 1967, Burrows, 1968, Hass, 1973). Adult feline whipworms have been recovered from Madison, Wisconsin (Hass 1976) and from Miami, Florida (Hass, 1978, Hass and Meisels, 1978), the Bahama Islands (Clarkson and Owen, 1959), Cuba, and Venezuela in the Americas, from Switzerland and Poland (the former East Prussia) in Europe (Enzie, 1951), and from Australia (Holmes and Kelly, 1972, Kelly, 1973, Ng and Kelly, 1975a).
LOCATION IN HOST: Members of the genus parasitize the cecum and colon.
IDENTIFICATION: The whipworm is composed of a thin, filamentous anterior end (the "lash" of the whip) and a thick posterior end (the whip's handle). Adult feline whipworms possess this unique whip shape (Hendrix, etal., 1987). Trichuriscampanula has been reported to be 20.5 to 38.0 mm long while Trichurisserrata has been reported to be 38.0 to 49.5 mm long (Hass and Meisels, 1978, Ng and Kelly, 1975a). However, for the present, it is best to just consider that these worms are probably less than 5 cm in length.
The egg of the feline whipworm may be described as being "trichinelloid" (Campbell, 1991) or "trichuroid," possessing a thick, yellow-brown, symmetrical shell with polar plugs at both ends and is unembryonated (not larvated) when laid (Hendrix, et al., 1987). The eggs of Trichuriscampanula described by Hass and Meisels (1978) averaged 63 to 85 µm by 34 to 39 µm; while those of Trichurisserrata described by Ng and Kelly (1975a) averaged 54 by 40 µm.
It is important to remember that Trichurisfelis eggs may be easily confused with those of Eucoleusaerophilus, Aonchothecaputorii, and Pearsonemafeliscati. It is also easy to confuse the eggs of the feline trichurids with the eggs of members of the genus Anatrichosoma. The eggs of Trichuris and the capillarids are unembryonated while those of Anatrichosoma contain a larva.
LIFE CYCLE: Nematodes of the genus Trichuris are parasites of the large intestinal mucosal epithelium. In this site, the adult worms live, feed, and move slowly. Adult female whipworms are oviparous, producing typical double operculated eggs that pass to the external environment each day in the host's feces. In spite of adverse environmental conditions, whipworm eggs are markedly resistant to the elements and may remain viable in the soil for months or even years under optimal conditions. While in the external environment, the egg develops to the stage which contains the infective larva.
The eggs of Trichuriscampanula embryonate within a 3-week period (Hass and Meisels, 1978). Using eggs from a case in Miami,FLorida, USA, these authors experimentally infected four cats, and three eventually shed eggs in their feces, with prepatent periods of 62, 76, and 91 days. We know almost nothing about how or where these worms develop within the intestine of the cat, although based on work with the mouse and canine forms, it is assumed that development all takes place within the intestinal mucosa.
CLINICAL PRESENTATION AND PATHOGENESIS: There have been numerous reports of whipworm infections in cats; however, these reports were primarily the results of fecal flotation procedures. There have been no descriptions of clinical signs or pathology associated with feline trichuriasis. Prescott (1984) states that the pathogenesis of Trichuris species in the cat is unknown since heavy infections have not been recorded. Actual recovery of feline whipworms from cats at necropsy is rare; the maximum number of worms recovered from any one cat is reported at six (Ng and Kelly, 1975a).
TREATMENT: Prescott (1984) recommends the use of fenbendazole (50 mg/kg once a day for three consecutive days to treat whipworms in the cat. This dosage was extrapolated from the dosage for the dog.
DIAGNOSIS: The egg of the feline whipworm possesses a thick, yellow-brown, symmetrical shell with polar plugs at both ends and is unembryonated (not larvated) when laid. The eggs of Trichuriscampanula average 63 to 85 mm by 34 to 39 mm; those of Trichurisserrata average 54 by 40 mm (Hass and Meisels, 1978, Ng and Kelly, 1975a).
EPIZOOTIOLOGY: Infected domestic cats may serve as carriers. The exact role of wild Felidae (Cameron, 1936, Prescott, 1984) in the epizootiology of feline trichuriasis has not been determined.
HAZARDS TO OTHER ANIMALS: Although whipworms parasitize the lower bowel of a variety of both domestic and wild animals, these helminths are extremely host specific (Soulsby, 1982). There have been reports of the presence of the feline trichurids in larger members of the Felidae family (Cameron, 1936, Prescott, 1984).
HAZARDS TO HUMANS: Human infections with feline trichurids have not been recorded in the literature (Ng and Kelly, 1975b). Although canine trichurids have been associated with human infections worldwide, the rarity of infection and low parasite numbers in cats makes the role of the cat of little importance in this zoonosis (Prescott, 1984).
CONTROL/PREVENTION: Effective control of feline whipworms involves proper diagnoses, therapy and sanitation of the cattery. To prevent reinfection, one must remove feces daily from the litterbox. Overcrowding of cats should be avoided in the cattery. Confining many animals to a small area increases environmental contamination and encourages transmission.
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