Sarcocystis leporum was found in 42 of 173 (24.3 %) cottontail rabbits (Sylvilagus floridanus mearnsi) examined. Infections were not observed in cottontails less than 6 months old. Incidence rose from zero at age 5 months to 67% at age 12 months. Ninety per cent of cottontails 25-48 months old were infected. The age of individual cottontails was estimated from the eye lens weight

Vande Vusse, Frederick J.

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Sarcocystis Infections in Relation to Age of Iowa Cottontails (Protozoa: Sarcocystidae)

University of Northern Iowa

Proceedings of the Iowa Academy of ScienceVolume 72 | Annual Issue Article 741965Sarcocystis Infections in Relation to Age of IowaCottontails (Protozoa: Sarcocystidae)Frederick J. Vande VusseIowa State UniversityCopyright © Copyright 1965 by the Iowa Academy of Science, Inc.Follow this and additional works at: http://scholarworks.uni.edu/piasThis Research is brought to you for free and open access by UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academyof Science by an authorized editor of UNI ScholarWorks. For more information, please contact scholarworks@uni.edu.Recommended CitationVande Vusse, Frederick J. (1965) "Sarcocystis Infections in Relation to Age of Iowa Cottontails (Protozoa: Sarcocystidae)," Proceedingsof the Iowa Academy of Science: Vol. 72: No. 1 , Article 74.Available at: http://scholarworks.uni.edu/pias/vol72/iss1/74Sarcocystis Infections in Relation to Age of Iowa Cottontails (Protozoa: Sarcocystidae)1 FREDERICK J. VANDE VussE2 Abstract. Sarcocystis leporum was found in 42 of 173 ( 24.3 % ) cottontail rabbits ( Sylvilagus floridanus mearnsi) examined. Infections were not observed in cottontails less than 6 months old. Incidence rose from zero at age 5 months to 67% at age 12 months. Ninety per cent of cottontails 25-48 months old were infected. The age of individual cottontails was estimated from the eye lens weight. Sarcocystis is cosmopolitan, protozoan parasite of voluntary and cardiac muscle found primarily in herbivores. Over 50 species have been described from mammals, birds and reptiles. While the taxonomic position of the group is unsettled, recent reports indicate it is related to Toxoplasma ( Manwell and Drobeck, 1953). Reviews of Sarcocystis literature are provided by Scott ( 1939 and 1943) and Levine ( 1961). Although recog-nized in the cottontail over 70 years ago, Sarcocystis has ap-parently been overlooked by many investigators, since it is rarely mentioned in the numerous papers on cottontail parasites. Miescher' s original report of Sarcocystis in 1843 was based on material from a house mouse. Its presence in rabbits in Germany was noted by Manz in 1867. Stiles reported Sarcocystis in a cottontail, Lepus sylvaticus (Sylvilagus floridanus), from Mary-land in 1894. Brumpt named Sarcocystis cuniculi from the European hare (Oryctolagus cuniculi) in 1913, but gave no de-scription of the parasite. A second species, S. leporum, was de-scribed by Crawley in 1914 from a cottontail now known to be Sylvilagus floridanus (Erickson, 1946) in Maryland. Crawley also reported records of Sarcocystis from a cottontail taken in Pennsylvania and from rabbits that probably were cottontails from New York and Illinois (Erickson, 1946). Erickson ( 1946) stated that the name S. leporum Crawley, 1914, should be used for the sarcosporidian of the cottontail. He considered S. cuniculi Brumpt, 1913, nomen nudum since no description was given. Annual reports to the legislature by the New York Con-servation Department (Section on Pathological Examination of 1 This study was supported in part by a grant from the Iowa State University Alumni Achievement Fund. •Department of Zoology and Entomology, Iowa State University Ames, Iowa. 524 1Vande Vusse: Sarcocystis Infections in Relation to Age of Iowa Cottontails (PrPublished by UNI ScholarWorks, 19651965) SARCOCYSTIS IN IOWA COTTONTAILS 525 Game) for 1935, 1936 and 1938-1940 stated that sarcocystis was found in 121 of 1438 cottontails examined, an incidence of 7.7%. Infections ranged from 0.5% in 1938 to 29.4% in 1936. Morgan and Waller ( 1940) reported Sarcocystis in 20 of 199 cottontails (S. floridanus mearnsi) collected in Iowa. Bell and Chalgren ( 1943) found infections in four of 45 cottontails from New York, one of 67 from Virginia and nine of 65 from Missouri. Thirty of 78 cottontails (S. floridanus mearnsi) from southern Minnesota examined by Erickson ( 1946) were in-fected. Two heavily infected cottontails (S. floridanus similis) from eastern South Dakota were examined by Hugghins ( 1961). Sarcocysts ( Miescher' s tubules) are located within muscle .fiber bundles, lying parallel to the fibers, and cause considerable distention of the bundles. In fresh muscle, they appear as thin, white spindles up to 8 mm long and 0.4 mm wide. Sarcocysts are most easily seen in the hind leg and loin of the cottontail. The outer of the two layers of the cyst wall has villiform projections, cytophaneres, which apparently derive nourishment from surrounding muscle tissue. The inner layer produces septa dividing the lumen of the cyst into compartments (Frenkel, 1956). In the mature cyst, the compartments are filled with thousands of banana-shaped trophozoites measuring 12 by 4 microns. Trophozoites may range from 6-16 microns in length (Levine, 1961). The life cycle of Sarcocystis in the cottontail has not been worked out. Scott's ( 1943) report on the life history of S. tenella in sheep and the work of Spindler et al. ( 1946) on transmission of S. miescheriana of swine indicated that the cycle was direct and did not involve an intermediate host. Trophozoites pass out with feces of an infected animal and are ingested by the same or another animal. A latent period, about which little is known, occurs between ingestion of trophozoites and appear-ance of cysts in muscle tissue. A latent period of 45 days has been reported for the mouse (Smith, 1901; Negre, 1907), a minimum of 6 weeks in lambs and pigs (Bergmann, 1913 and Scott, 1943) and 10 weeks for calves (Scott, 1943). A latent period of 3 months was more common for lambs and calves ( Scott, 1943) . Some species of Sarcocystis have been sho\-vn to contain a powerful, heat-labile endotoxin, sarcocystin. Sato ( 1926) re-ported that the intravenous minimum lethal dose for the rabbit of an extract of S. fusiformis from the ox was 0.05 mg/kg of body weight. When uncooked infected flesh was fed to experi-mental animals, a loss of intestinal epithelium by mice was re-ported by Crawley ( 1916) and vomiting, diarrhea and temporary 2Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 74http://scholarworks.uni.edu/pias/vol72/iss1/74526 IOWA ACADEMY OF SCIENCE [Vol. 72 posterior paralysis in swine were observed by Spindler et al. (1946). Sarcocystis is not generally considered very pathogenic (Le-vine, 1961) and nothing is known of its effect on cottontails. Spindler et al. ( 1946) indicated that heavily infected swine were unthrifty and showed signs of muscular stiffness. METHODS L?ata for this paper were obtained from cottontails (S. flor-idarius mearnsi) taken in Ames, Story County, Iowa during January 1962 to January 1963. Age of individual animals was estimated with the method of Lord ( 1950) as modified by Dudley ( 1963) utilizing weight of the eye lens. Sex of the specimens w:as determined by internal examination. The surface of the muscle of the hind legs and loins was examined for pres-ence of visible sarcocystis which were situated thoughout the muscle, but visible only when near the surface. Thus, some very light infections may have been overlooked. RESULTS One-hundred seventy-three cottontails ( 88 males and 85 fe-males), ranging in age from 1-48 months, were examined. Sarcocystis leporum was observed in 42 (24.3%). However, sar-cocystis was not observed in cottontails less than 6 months old. Incidence rose from zero at age 5 months to nearly 70% by age 12 months. Ninety per cent of cottontails 25-48 months old were infected. (Table 1). Table 1. Age of Iowa cottontails in relation to Sarcocystis infection. Age in Number Per cent Age in Number Per cent months examined infected months examined infected 1 9 0 8 5 60 2 12 0 9 11 36 3 19 0 10 9 67 4 18 0 11-15 12 67 5 18 0 16-24 13 62 6 14 29 25-48 10 90 7 7 14 1-48 173 24 Incidence was lowest in summer and fall when cottontails less than 6 months old comprised most of the population. In-cidence rose through late fall and winter, reaching a maximum in the spring, when addition of young, uninfected individuals reduced overall incidence (Table 2). Forty-two of 96 cottontails ( 43.8%) 6 months of age or older were infected. Sixteen of 48 males ( 33.3%) and 26 of 48 females ( 54.2%) had Sarcocystis in their muscles. The diHerence in rate of 3Vande Vusse: Sarcocystis Infections in Relation to Age of Iowa Cottontails (PrPublished by UNI ScholarWorks, 19651965] SARCOCYSTIS IN IOWA COTTO NT AILS 527 Table 2. Seasonal variation of incidence of Sarcocystis in Iowa cotton-tails. Number Per cent Number Per cent Month examined infected Month examined infected January 19 50 July 14 7 February 7 29 August 19 10 March 22 45 September 10 30 April 18 50 October 20 15 May 9 56 November 16 6 June 11 27 December 7 14 infection between sexes appears to be a result of unequal sampling rather than a difference in susceptibility. Males pre-dominated in the low-incidence (6-15 month) age groups, while females outnumbered males two to one in the high incidence ( 25-48 month) age group. Relative density of cysts in individual cottontails was noted, although quantitative measur:ements were not made. Light in-fections were most common in young rabbits, while heaviest infections occurred in older animals. D1scuss10N If the life cycle of Sarcocystis in cottontails is similar to that of sheep and swine, and involves direct infection, juvenile cot-tontails could ingest trophozoites as early as their second week, when they begin to take solid food. The 5 months between birth and appearance of sarcocysts in cottontails is considerably longer than 6-12 weeks reported for other animals. This may represent a true difference in latent period for the cottontail; or, perhaps a physical or physiological mechanism acts to prevent infections in very young cottontails. Cottontails regularly re-ingest a portion of their feces which, presumably, would main-tain and increase the infection. Variation in the incidence of sarcocystis in cottontails exists in the reports in the literature. In view of the relationship be-tween age and incidence, the season in which collections are made has a definite bearing on the incidence reported. AcKL-..oWLEDGEMENTS The writer wishes to thank Dr. Arnold 0. Haugen, Leader of the Iowa Cooperative Wildlife Research Unit for providing laboratory facilities and field expenses for this study. Mr. Paul Kline of the S.tate Conservation Commission kindly provided additional specimens for study. Thanks go also to Dr. Haugen and to Dr. Martin J. Ulmer for critical review of the manuscript. 4Proceedings of the Iowa Academy of Science, Vol. 72 [1965], No. 1, Art. 74http://scholarworks.uni.edu/pias/vol72/iss1/74528 IOWA ACADEMY OF SCIENCE [Vol 72 Literature Cited Anonymous. 1935. Annual report to the legislature of the New York Con-servation Department. Section on pathological examination of game. New York Dept., Albany. -----. ibid. 1936. -----. ibid. 1938. -----. ibid. 1939. -----. ibid. 1940. Bell, J. F. and W. S. Chalgren. 1943. Some wildlife diseases in the eastern United States. J. Wildl. Mgmt. 7 :270-278. Bergman, Arvid M. 1913. Beitrag zur Kenntniss des Vorkommens Sarkos-poridien bei den Haustieren. Z. Fleisch u. Milchhygiene Berlin. 23:169-180. Brumpt. E. 1913. Precis de parasitologie. 2nd ed. Masson et Cie, Paris. Crawley, H. 1914. Two new sarcosporidia. Phildelphia Acad. Nat. Sci. Proc. 66:214-218. -----. 1916. The sexual evolution of Sarcocystis muris. Acad. Nat. Sci. Proc. Philadelphia 68:2-43. Dudley, Eugene F. 1963. Age structure of populations of :\1ichigan cotton-tail rabits ( Sylvi'lagus floridanus) as determined by an improved lens weight technique for age determination. Unpublished Ph. D. Thesis . . Univ. of Michigan Library, Ann Arbor. Erickson, Arnold B. 1946. Incidence and transmission of Sarcocystis in cottontails. J. Wildl. Mgmt. 10:44-46. Frenkel, J. K. 1956. Pathogenesis of toxoplasmosis and of infections re-sembling Toxoplasma. Ann. N. Y. Acad. Sci. 64:215-251. Hugghins, Ernest J. 1961. Sarcocystis in cottontail rabbits. Proc. S. D. Acad. Sci. 15:240. Levine, Norman D. 1961. Protozoan parasites of domestic animals and man. Burgess Puhl. Co., Minneapolis, Minn. 412 p. Lord, Rexford D., Jr. 1950. The lens as an indicator of age in cottontail rabbits. J. Wildl. Mgmt. 23:358-360. Manwell, R. D. and H. P. Drobeck. 1953. The behavior of Toxop'lasma, with notes on its taxonomic status. J. Parasitol. 39:577-584. Manz, \V. 1867. Beitrag zur Kenntnis der Miescher'schen Schlauche. Arch. Mikr. Anat. 3:345-357. Miescher, F. 1843. Ueber eigenthumliche Schlauche in dem Muskeln einer Hausmaus. Ber. Verhandl. Naturf. Gellsch. in Basel. 5:198-202. (in Scott, 1930). Morgan, B. B. and E. F. Waller. 1940. A survey of the parasites of the Iowa cottontail Sylvilagus floridanus mearnsi. J. Wildl. Mgmt. 4:21-26. Negre, L. 1907. Sarcosporidiose experimentale. Compt. Rend. Soc. Biol 68:997. Sato, S. 1926. On the toxic aotion of sarcosporidiotoxin and its sero-logical study. J. Japan. Soc. Vet. Sci. 5:25-27. Scott, J. W. 1930. The sarcosporidi:a, a critical review. J. ParasitoL 16: 111-130. -----. 1943. Life history of sarcosporidia, with particular reference to Sarcocystis tenel'la. Bull. Wyo. Agr. Exp. Sta. No. 259. Smith, Theobald. 1901. The production of sarcosporidiosis in the mouse bx feeding infected muscular tissue. J. Exptl. Med. 6: 1-'.U. Spindler, L. A., Harry E. Zimmerman Jr. and Daniel S. Jaquette. 1946. Transmission of Sarcocystis to swine. Proc. Helminthol. Soc. Wash. 13: 1-11. Stiles, C. W. 1894. New American finds of sarcosporidia Vet. Mag., Philadelphia 1:728. 5Vande Vusse: Sarcocystis Infections in Relation to Age of Iowa Cottontails (PrPublished by UNI ScholarWorks, 1965

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Sarcocystis Infections in Relation to Age of Iowa Cottontails (Protozoa: Sarcocystidae)

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