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Epidemiology of nematode infections of Soay sheep (Ovis aries L.) on St Kilda

  • F. M. D. Gulland (a1) and M. Fox (a2)

Summary

The epidemiology of nematode infections of Soay sheep on the island of St Kilda over a period of 2 years (August 1988–August 1990) spanning a host population crash is described. Infective larvae (L3) levels on pasture were high (2422±365 L3/kg D.M. grass in midsummer 1988) when host population density was high, decreasing after the sheep population declined by 70% in early 1989 (601 ±14 L3/kg D.M. in midsummer 1989). The availability of infective larvae to sheep increased during the winter of 1988–1989, probably as a result of concentration of existing larvae on grass as vegetation was destroyed by bad weather and overgrazing. Increased availability of pre-parasitic stages was accompanied by a marked increased in faecal egg counts from sheep of all ages and both sexes. Prevalence and intensity of infection (faecal egg counts) were higher in males than females throughout the 2-year study (χ2 = 208.3, P < 0.005 and F1.2000 = 304, P < 0.001 respectively), except during the lambing periods, and decreased with age in both sexes. Changes in prevalence and intensity of strongyle infections were associated with changes in host population density. Prevalence and intensity of Dictyocaulus filaria larvae in faeces increased during the host population crash. Infection intensity decreased with age (F1.203 = 44.02, P < 0.001) and was higher in males than females (F1.203 = 13.45, P < 0.001).

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Albon, S. D., Mitchell, B., Huby, B. J. & Brown, D. (1986). Fertility in female Red deer (Cervus elaphus): the effects of body composition, age and reproductive success. Journal of Zoology 209, 447–60.
Anderson, R. M. & Crombie, J. A. (1984). Experimental studies of age-prevalence curves for Schistosoma mansoni infections in populations of Biomphalaria glabrata. Parasitology 89, 79105.
Anderson, R. M. & May, R. M. (1978). Regulation and stability of host–parasite population interactions. I. Regulatory processes. Journal of Animal Ecology 47, 219–47.
Anderson, R. M. & May, R. M. (1979). Population biology of infectious diseases: Part I. Nature, London 280, 361–7.
Armour, J. (1980). The epidemiology of helminth disease in farm animals. Veterinary Parasitology 6, 746.
Armour, J. (1989). The influence of host immunity on the epidemiology of trichostrongyle infections in cattle. Veterinary Parasitology 32, 519.
Barger, I. A. (1987). Population regulation in trichostrongylids of ruminants. International Journal for Parasitology 17, 531–40.
Boag, B. & Thomas, R. J. (1970). The development and survival of free living stages of Trichostrongylus colubriformis and Ostertagia circumcincta on pasture. Research in Veterinary Science 11, 380–1.
Boag, B., Topham, P. B. & Webster, R. (1989). Spatial distribution on pasture of infective larvae of the gastrointestinal nematode parasites of sheep. International Journal for Parasitology 19, 681–5.
Clutton-Brock, J. (1981). Domesticated Animals from Early Times. London: British Museum (Natural History) and Heinemann.
Clutton-Brock, T. H., Price, O. F., Albon, S. D. & Jewell, P. A. (1991). Persistent instability and population regulation in Soay sheep. Journal of Animal Ecology 60, 593608.
Crofton, H. D. (1949). The ecology of immature stages of Trichostrongyle nematodes. III. Larval populations on hill pastures. Parasitology 39, 274–80.
Crofton, H. D. (1958). Nematode parasite populations in sheep on lowland farms. VI. Sheep behaviour and nematode infections. Parasitology 48, 251–60.
Donald, A. D. (1967). Population studies on the infective stage of some nematode parasites of sheep. I. The frequency distribution of strongyloid infective larvae in random samples of pasture. Parasitology 57, 263–79.
Donald, A. D. & Leslie, R. T. (1969). Population studies on the infective stage of some nematode parasites of sheep. II. The distribution of faecal deposits on fields grazed by sheep. Parasitology 59, 141–57.
Downey, N. E. & Conway, A. (1968). Grazing management in relation to trichostrongylid infestation in lambs. 1. Influence of stocking rate on the level of infestation. Irish Journal of Agricultural Research 7, 343–62.
Dunsmore, J. D. & Dudzinski, M. L. (1968). Influence of numbers of nematode parasites in wild rabbits Oryctolagus cunicuius (L.), to host sex, age, and season. Journal of Parasitology 54, 462–74.
Genstat 5 Committee (1987). Genstat 5 Reference Manual, Oxford: Oxford University Press.
Gettinby, G., Mckellar, Q. A., Bairden, K., Theodoris, V. & Whitelaw, A. (1985). Comparison of two techniques used for the recovery of nematode infective larvae from pasture. Research in Veterinary Science 39, 99102.
Gibson, T. E. (1963). Experiments on the epidemiology of Nematodiriasis. Research in Veterinary Science 4, 258–68.
Gibson, T. E. & Everett, G. (1972). The ecology of the free living stages of Ostertagia circumcincta. Parasitology 64, 451–60.
Grenfell, B. T. (1988). Gastrointestinal nematode parasites and the stability and productivity of intensive ruminant grazing systems. Philosophical Transactions of the Royal Society of London, B321, 541–63.
Grenfell, B. T., Price, O. F., Albon, S. D. & Clutton-Brock, T. H. (1992). Overcompensation and population cycles in an ungulate. Nature, London 355, 823–6.
Gulland, F. M. D. (1992). The role of nematode parasites in Soay sheep (Ovis aries L.) mortality during a host population crash. Parasitology 105, 493503.
Hansen, J. W., Nansen, P. & Foldager, J. (1981). The importance of stocking rate to the uptake of gastrointestinal nematodes by grazing calves. In Epidemiology and Control of Nematodiasis in Cattle, (ed. Nansen, P., Jorgensen, R. J. & Soulsby, E. J. L.) pp. 471494. Brussels: ECSC, EEC, EAEC.
Haukisalmi, V., Henttonen, H. & Tenora, F. (1988). Population dynamics of common and rare helminths in cyclic vole populations. Journal of Animal Ecology 57, 807–25.
Hudson, P. J., Dobson, A. P. & Newborn, D. (1985). Cyclic and non-cyclic populations of red grouse: a role for parasitism? In Ecology and Genetics of Host–Parasite Interactions, (ed. Rollinson, D. & Anderson, R. M.) pp. 7990. London: Academic Press.
Jewell, P. A., Milner, C. & Boyd, J. M. (1974). Island Survivors. London: Athlone Press.
Keith, L. B., Cary, J. R., Yuill, T. M. & Keith, I. M. (1985). Prevalence of helminths in a cyclic snowshoe hare population. Journal of Wildlife Diseases 21, 233–53.
Keymer, A. E. (1981). Population dynamics of Hymenolepis diminuta in the intermediate host. Journal of Animal Ecology 50, 941–50.
Lancaster, M. B. (1970). The recovery of infective larvae from herbage samples. Journal of Helminthology 44, 219–30.
May, R. M. & Anderson, R. M. (1978). Regulation and stability of host–parasite populations. II. Destabilizing processes. Journal of Animal Ecology 47, 249–67.
May, R. M. & Anderson, R. M. (1979). Population biology of infectious diseases. Part II. Nature, London 280, 455–61.
Michel, J. F. (1976). The epidemiology and control of some nematode infections in grazing animals. Advances in Parasitology 14, 355–97.
Ministry of Agriculture Fisheries and Food (1971). Manual of veterinary parasitological laboratory techniques. Technical Bulletin 18, London: HMSO.
Reddington, J. J., Stewart, G. I., Kramer, G. W. & Kramer, M. A. (1981). The effect of host sex and hormones on Trichinella spiralis in the mouse. Journal of Parasitology 67, 548–55.
Salih, N. E. & Grainger, J. N. R. (1982). The effect of constant and changing temperature on the development of the eggs and larvae of Ostertagia circumcincta. Journal of Thermal Biology 7, 35–8.
Scott, M. E. (1987). Regulation of mouse colony abundance by Heligmosomoides polygyrus. Parasitology 95, 111–24.
Scott, M. E. & Anderson, R. M. (1984). The population dynamics of Gyrodactylus bullatarudis (Monogenea) on guppies (Poecilia reticulata). Parasitology 89, 159–94.
Scott, M. E. & Dobson, A. (1989). The role of parasites in regulating host abundance. Parasitology Today 5, 176–83.
Southcott, W. E., Langlands, J. P. & Heath, D. D. (1970). Stocking density and nematode infections of grazing sheep. Proceedings of the 11th International Grassland Congress, Australia, pp. 888890.
Taylor, E. L. (1939). Technique for the estimation of pasture infestation by strongyloid larvae. Parasitology 31, 473–8.
Uriate, J. & Valderrabano, J. (1989). An epidemiological study of parasitic gastroenteritis in sheep under an intensive grazing system. Veterinary Parasitology 31, 7181.
Wakelin, D. (1987). The role of the immune response in helminth population regulation. International Journal for Parasitology 17, 549–57.
Weinstein, Y., Ran, S. & Segal, S. (1984). Sex associated differences in the regulation of immune responses controlled by the MHC of the mouse. Journal of Immunology 132, 656–61.
Yadav, C. L. (1987). The epidemiology and control of sheep nematodes. Ph.D. thesis, University of Liverpool.
Young, R. R., Anderson, N., Overend, D., Tweedie, R. L., Malafont, K. W. J. & Preston, G. A. N. (1980). The effect of temperature on times to hatching of eggs of the nematode Ostertagia circumcincta. Parasitology 81, 477–91.

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Epidemiology of nematode infections of Soay sheep (Ovis aries L.) on St Kilda

  • F. M. D. Gulland (a1) and M. Fox (a2)

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