Robert A. Knight

Experimental cross infections of Fasciola hepatica in lambs and calves.

The effects of experimental infections with Fasciola hepatica of ovine and bovine origin in homologous and heterologous hosts and in uninfected controls were compared; groups comprised 5 animals each. The effects of the infections were monitored by biweekly determinations of packed cell volumes (PCV), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), gamma glutamyl transpeptidase (GGT), serum iron, bilirubin levels, alkaline phosphatase (AlP) and total serum protein levels. Infected animals showed changes in SGOT, SGPT and GGT activity levels, and GGT activity levels, and infected lambs showed changes in PCV and AlP. However, no no significant differences in these serum levels between infected host groups were attributable to fluke strain. At necropsy, calves infected with ovine and bovine strains on an average had about the same number of flukes, but lambs infected with a high dose of the bovine strain on the average had nearly twice the number of flukes as those infected with ovine strain. Weight gains did not differ within host groups; liver damage was extensive in all infected animals. On the basis of these experiments, the pathogenicity of the ovine and the bovine strains of F. hepatica appears to be the same.

Trichuris oreamnos sp. n. from the mountain goat, Oreamnos americanus (Blainville), in British Columbia, Canada, and a key to trichurids in North American ruminants.

The new species, from the cecum of 2 mountain goats killed on Wardle Mountain, Kootenay National Park, British Columbia, Canada, is characterized by males with spicules 3.17 to 4.27 mm long which are acutely pointed, an ejaculatory duct which is longer than the vas deferens, and a spinous spicular sheath which has an expansion near its center. Females have a spinous vulva, not everted, a large expansion of the posterior vagina just before the uterine sphincter, and a nearly straight posterior portion. This constitutes the 5th species of Trichuris recovered from ruminants in North America, and a key is presented to facilitate differentiation of the 5 species. This paper is the result of a study of whipworms sent to the writer by Dr. W. M. Samuel, The University of Alberta, Edmonton 7, Canada. The worms were collected from the ceca of two mountain goats, Oreamnos americanus, killed on Wardle Mountain in the Kootenay National Park, British Columbia, Canada, by W. M. Samuel and J. Stelfox in 1972. Twentysix males and 45 females were recovered, 53 from one goat and 18 from the other. The worms had been preserved in alcohol and were in good condition, except for many missing anterior portions. Since the whipworms fit no known description, they are considered a new species, and the name Trichuris oreamnos is proposed for them. MATERIALS AND METHODS The whipworms were cleared in lactophenol for study and were measured by means of an ocular micrometer. Twenty-six adult male and female worms were studied and measured (Table I). Certain characters could not be seen in some specimens; for these, the averages are based on fewer than 26 measurements. Two females were cut to free their eggs; 25 were measured from each worm. Twenty-four male and 20 female characters were used to describe the species. All measurements are presented in microns unless stated otherwise. Trichuris oreamnos sp. n. (Figs. 1-4) Description Males Length of body, 38.6 to 59.0 mm; of anterior esophageal portion, 23.9 to 42.7 mm; of posterior Received for publication 27 September 1973. *Animal Parasitology Institute, ARS, Beltsville, Maryland 20705. portion, 13.3 to 20.5 mm. Anterior portion 240 to 310 wide at level of junction of esophagus and intestine; posterior portion 420 to 590 wide at level of junction of vas deferens and ejaculatory duct. Cuticular vesicles begin 540 to 740 from anterior end and extend 1.40 to 2.35 mm posteriad along edges of bacillary band. Spicule 3.17 to 4.27 mm long, proximal portion expanding into a flare 25 to 55 wide, whereas spicular shaft measures 15 to 25; distal end of spicule acutely pointed (Fig. 4). Testis originates near beginning of cloaca, 1.30 to 4.44 mm from posterior end of body; proceeds forward straight and uncurved 1.21 to 3.23 mm, then rapidly becomes tightly convoluted anteriad. Testis 10.3 to 16.5 mm long; at anterior end narrows and becomes straight to form vas efferens 0.40 to 1.04 mm long, which turns posteriad about level of beginning of intestine. Shortly after this turn, expands to form vas deferens, 2.37 to 5.02 mm long. Vas deferens with thin walls separated from ejaculatory duct by a variably sized constriction with heavily muscular walls 260 to 430 long. Ejaculatory duct with thick muscular walls, 7.32 to 11.51 mm long. Ratio of ejaculatory duct to vas deferens from 2.08 to 4.22:1. Cloaca 1.98 to 4.07 mm long; spicular pouch opens in dorsal wall of cloaca 1.02 to 3.29 mm from cloacal opening and proceeds anteriad a variable distance depending upon distance spicule is extruded. Everted spicular sheath 30 to 43 wide at cloacal opening, proceeds with a uniform width for a distance, then expands to a maximum width 80 to 140 wide. Sheath distal to expansion tapers to a diameter comparable to cylindrical portion proximal to expansion (Fig. 2). Sheath covered with spines past expansion. No sheath seen completely everted. Cloaca opens terminally or subterminally, on either side large caudal papilla, 15 to 20 wide.

Trichuris odocoileus sp. n. (Nematoda: Trichuridae) from white-tailed deer, Odocoileus virginianus, in southeastern U.S., and a key to trichurids in North American ruminants.

A new species of Trichuris from the cecum of white-tailed deer, Odocoileus virginianus, from the southeastern United States, is characterized herein. Males had spicules 2.20 to 3.05 mm long with bluntly rounded tips, an ejaculatory duct equal to or slightly longer than the vas deferens, and a spinous spicular sheath with an expansion near its center. Females had a spinous vulva, usually not everted, a loop in the oviduct just before it opened into the uterus, and a slightly curved posterior portion. Trichuris odocoileus was differentiated from T. lani , a species described in Russia which is most like T. odocoileus, by 1) possessing a spicular sheath with a central expansion, 2) greater size with longer ejaculatory duct and vas deferens, 3) slightly larger eggs, and 4) the unique loop in the oviduct. Trichuris odocoileus constitutes the 6th species of Trichuris recovered from North American ruminants. A key is provided to facilitate differentiation of the six species.

Relationship of globule leucocytes to infections with Fasciola hepatica in sheep.

The presence of globule leucocytes (GL) within tissues of animal organs has been associated with various parasitic helminth infections. The GL is a nonepithelial cell found in and under epithelia. It is distinct from the Russell body cell, and evidence supports the thymus-dependent mast cell as its precursor (Gregory 1979, Vet. Bull. 49: 821-827). Sommerville (1965, Aus. Vet. J. 32: 237-240) found GL in abomasums of sheep with mixed nematode infections. Dobson (1965, Aus. J. Sci. 28: 434; 1966, Aus. J. Agric. Res. 17: 955-966; 1966, Nature 211: 875) reported GL in the gastrointestinal tracts of sheep with infections of Oesophagostomum columbianum and concluded that their presence reflected an immunological response. Lawrence (1977, Res. Vet. Sci. 23: 239-240) studied GL in lungs, livers, bladders, and kidneys, in addition to the gastrointestinal tracts, of cattle infected with Schistosoma mattheei. He concluded that they were most numerous and in more organs in animals subjected to repeated infections. Campbell et al. (1978, Vet. Parasitol. 4: 143-152) found GL in the bile ducts of sheep infected one time with Fasciola hepatica. In conjunction with another study, the opportunity arose to examine sheep infected singly and repeatedly with F. hepatica to determine whether GL might be present in tissues other than liver, and whether repeated infections would increase their numbers. Five groups of 10, 8-mo-old, helminth-free lambs were used. Groups 1 through 4 were inoculated with F. hepatica (Knight, 1980, Proc. Helminthol. Soc. Wash. 47: 186-191). Group 5 comprised uninfected lambs (Table I). At necropsy, a tissue sample was taken from liver, abomasum, kidney, cecum, lung, and small intestine and placed in buffered formolsaline. The tissues were imbedded in paraffin, sectioned, and stained with hematoxylin and eosin by conventional methods. One section of tissue from the excised sample was studied, and the area with the greatest number of GL was located under the low power of a compound microscope. Because the GL were not uniformly dispersed throughout the s ction of tissue, a coded value (score) from 0 to 10 was given to the tissue sample; this value was based on the number of GL present in a field of view under high dry (x40) power in that portion containing the densest concentration of GL (Table II). The coded values for each group were subjected to analysis of variance after square root transformation. Group means were separated by Kramers modification (1956, Biometrics 12: 307-310) of Duncans new multiple range test.