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Characteristics of parasite populations in endemic trichostrongylidosis

Published online by Cambridge University Press:  06 April 2009

J. H. Whitlock ,
H. D. Crofton  and
J. R. Georgi
J. H. Whitlock
Affiliation:
New York State Veterinary College, Cornell University
H. D. Crofton
Affiliation:
New York State Veterinary College, Cornell University Department of Zoology, University of Bristol
J. R. Georgi
Affiliation:
New York State Veterinary College, Cornell University
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Extract

Worm counts, faecal egg counts and erythrocyte losses are recorded for lambs which were exposed on a naturally infected pasture for different periods in different years. After each exposure period the lambs were kept under conditions in which no further infection could occur; at varying times, usually after the infections had had time to maturo, the lambs were killed and examined. A detailed analysis of the results is given. It is concluded that the negative binomial distribution of worms among sheep within a flock is not a reflexion of the pasture distribution of infective stages but is the result of a combination of Poisson distributions, these distributions being generated by genetic subsets within the flock. There is a remarkable correlation between the numbers of Haemonchus present and the numbers of worms of the other genera. It is suggested that there are host-mediated common elements in the biomass regulating parameters of mixed trichostrongyle infections and that there is a resource-allocating device. Three main hypotheses are proposed. The hypotheses are: (1) The dimensional constraints on the host-parasite system are the results of various kinds of pace-setters or biological clocks. In each annual cycle the parent worms programme the rate of development through each generation. (2) The rate of development of the worms is tied stochastically or deterministically to the rate of senescence and death. (3) The rate of development and death for each trichostrongyle is set at the start of each season by a host factor which acts on a comparable area of the genome in each trichostrongyle. Methods of testing these hypotheses are discussed and the work related to other systems.

Type
Research Article
Information
Parasitology , Volume 64 , Issue 3 , June 1972 , pp. 413 - 427
Copyright
Copyright © Cambridge University Press 1972

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References

REFERENCES

Anderson, N., Armour, J., Jennings, F. W., Ritchie, J. D., & Urquhart, G. M., (1965). Inhibited development of Ostertagia ostertagi. Veterinary Record 77, 146–7.Google ScholarPubMed
Anderson, N., Armour, J., Jennings, F. W., Ritchie, J. D., & Urquhart, G. M., (1969). The sequential development of naturally occurring ostertagiasis in calves. Reserch in Veterinary Science 10, 18–28.CrossRefGoogle ScholarPubMed
Brown, D. P., & David, Igor B., (1968). Specific gene amplification in oocytes. Science 160, 272–9.CrossRefGoogle ScholarPubMed
Caullery, M., (1952). Parasitism and Symbiosis (trans. A. M. Lysaght). London: Sidgwick and Jackson.Google Scholar
Cole, L. C., (1954). The population consequences of life history phenomena. Quarterly Review of Biology 29, 103–37.CrossRefGoogle ScholarPubMed
Crofton, H. D., (1957). Nematode parasite populations in sheep on lowland farms. III. The seasonal incidence of species. Parasitology 47, 304–18.CrossRefGoogle ScholarPubMed
Crofton, H. D., & Whitlock, J. H., (1968). Changes in sex ratio in Haemonchus contortus cayugensis. Cornell Veterinarian 59, 388–92.Google Scholar
Donald, A. D., & Leslie, R. T., (1969). Population studies on the infective stages of some nematode parasites of sheep. II. The distribution of faecal deposits on fields grazed by sheep. Parasitology 59, 141–57.CrossRefGoogle ScholarPubMed
Elsdale, T. R., Fishberg, M., & Smith, S., (1958). A mutation that reduces nucleolar number in Xenopus laevis. Experimental Cell Research 14, 642–3.CrossRefGoogle ScholarPubMed
Georgi, J. R., (1969).Parasitology for Veterinarians. Philadelphia, Pa.: W. B. Saunders.Google Scholar
Georgi, J. R., & Whitlock, J. H., (1967). Erythrocyte loss and restitution in ovine haemonchosis. Estimation of erythrocyte loss in lambs following natural exposure. Cornell Veterinarian 57, 43.Google ScholarPubMed
Gregory, P. W., Miller, R. F., & Stewart, M. A., (1940). An analysis of environmental and genetic factors influencing stomach worm infestation in sheep. Journal of Genetics 39, 391–400.CrossRefGoogle Scholar
Hunter, G. C., & Quenouille, M. H., (1952). A statistical examination of the worm egg count sampling technique for sheep. Journal of Helminthology 26, 157–70.CrossRefGoogle Scholar
LeJambre, L. F., (1971). The adaptiveness of polymorphism in Haemonchus contortus. Thesis, Cornell University.Google Scholar
LeJambre, L. F., Crofton, H. D., & Whitlock, J. H., (1970). An assay technique for nematode egg hatchability. Transactions of the American Microscopical Society 89, 397–406.CrossRefGoogle Scholar
LeJambre, L. F., & Ractliffe, L. H., (1971). Seasonal change in a balanced polymorphism in Haemonchus contortus population. Parasitology 62, 151–6.CrossRefGoogle Scholar
LeJambre, L. F., Ractliffe, L. H., Uhazy, L. S., & Whitlock, J. H.(1971 a). Faecal egg output of lambs in relationship to Haemonchus burden. International Journal of Parasitology 1, 157–60.CrossRefGoogle ScholarPubMed
LeJambre, L. F., Ractliffe, L. H., Uhazy, L. S., & Whitlock, J. H.(1971 b). Evidence that the seasonal alternation of polymorphs apparent in linguiform Haemonchus contortus cayugensis also occurs in other phenotypes. International Journal of Parasitology. (In the Press.)Google Scholar
Northam, J. I., & Rocha, U. F., (1958). On the statistical analysis of worm counts in chickens. Experimental Parasitology 7, 428–38.CrossRefGoogle Scholar
Ohno, S., (1970). Evolution by Gene Duplication. New York: Springer.CrossRefGoogle Scholar
Sacher, G. A., (1966). Abnutzungstheorie in Perspectives in Experimental Gerontology (ed. Shock, N. W.), pp. 326–35. Springfield, Illinois: Charles C. Thomas.Google Scholar
Slobodkin, L. B., (1966). Growth and Regulation of Animal Populations. New York: Holt, Rinehart and Winston.Google Scholar
Whitlock, J. H., (1949). The relationship of nutrition to the development of trichostrongylidoses. Cornell Veterinarian 39, 146–82.Google Scholar
Whitlock, J. H., (1961). Parasitology, ecology and biometry. British Veterinary Journal 117, 337–48.CrossRefGoogle Scholar
Whitlock, J. H., (1963). A cybernetic approach to a natural epidemic of strongylatosis in sheep. Cornell Veterinarian 53, 505–34.Google ScholarPubMed
Whitlock, J. H., (1966). The Environmental Biology of a Nematode in Biology of Parasites, pp. 185–97. New York: Academic Press.Google Scholar
Whitlock, J. H., (1971). Ecdysis of Haemonchus and hypotheses. Cornell Veterinarian 61, 349–61.Google ScholarPubMed
Whitlock, J. H., & Robson, D. S., (1969). The analysis of population and environmental disease mechanisms. Cornell Veterinarian 59, 453–65.Google ScholarPubMed