Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-03T02:20:22.710Z Has data issue: false hasContentIssue false
  • English
  • Français

Intestinal helminths of man: the interpretation of egg counts

Published online by Cambridge University Press:  06 April 2009

Andrew Hall
Andrew Hall
Affiliation:
Molteno Institute, Downing Street, Cambridge CB2 3EE
Get access Rights & Permissions [Opens in a new window]

Extract

Of the 39 most common helminth parasites of man listed by Peters & Gilles (1977), 30 may be detected and often diagnosed by finding their eggs or larvae in the faeces of infected people. The preferred habitat of many of these helminths is the alimentary tract itself and the continual flow of material through the food tube provides a simple, passive and reliable means of transport and eventual exit from the host for the reproductive stages of a worm. Helminth eggs are generally less than 150 μm in diameter and although individually comprise a small material investment by the adult worm in the propagation of the species, the chances of infecting a host are so slim (though this may be a teleological inference) that adult worms are often highly fecund: a female Ascaris lumbricoides is estimated to release daily into the intestine approximately 200,000 eggs (WHO, 1967). Yet numbers should not always be equated with great substance or bulk – an equally important determinant of the chances of finding an egg in faeces: assuming a spherical diameter of 60 μm and a specific gravity of 1·2 (Sawitz, 1942) then a female Ascaris is estimated to produce only about 25 mg of eggs each day, which is 0·01% of a moderate daily output of 250 g of faeces.

Type
Trends and Perspectives
Information
Parasitology , Volume 85 , Issue 3 , December 1982 , pp. 605 - 613
Copyright
Copyright © Cambridge University Press 1982

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, A. H. V. & Ridley, D. S. (1970). Further observations on the formol–ether concentration technique for faecal parasites. Journal of Clinical Pathology 23, 343–52.CrossRefGoogle ScholarPubMed
Basta, S. S., Soekirman, M. S., Karyadi, D.& Scrimshaw, N. S. (1979). Iron deficiency anemia and the productivity of adult males in Indonesia. American Journal of Clinical Nutrition 32, 916–25.CrossRefGoogle ScholarPubMed
Brooks, R. M., Latham, M. C. & Crompton, D. W. T. (1979). The relationship of nutrition and health to worker productivity in Kenya. East African Medical Journal 56, 413–21.Google ScholarPubMed
Brown, H. W. (1975). Basic Clinical Parasitology, 4th edn.New York: Appleton-Century-Crofts.Google Scholar
Burkitt, D. P. (1973). Epidemiology of large bowel disease: the role of fibre. Proceedings of the Nutrition Society 32, 145–9.CrossRefGoogle ScholarPubMed
Cable, R. M. (1958). An Illustrated Laboratory Manual of Parasitology, 4th edn.Minneapolis: Burgess.Google Scholar
Croll, N. A., Anderson, R. M., Gyorkos, T. W. & Ghadirian, E. (1982). The population biology and control of Ascaris lumbricoides in a rural community in Iran. Transactions of the Royal Society of Tropical Medicine and Hygiene 76, 187–97.CrossRefGoogle Scholar
Cummings, J. H., Southgate, D. A. T., Branch, W., Houston, H., Jenkins, D. J. A. & James, W. P. T. (1978). Colonic responses to dietary fibre from carrot, cabbage, apple, bran and guar gum. Lancet 1, 5–9.CrossRefGoogle Scholar
Fairbairn, D. (1957). The biochemistry of Ascaris. Experimental Parasitology 6, 491–554.CrossRefGoogle ScholarPubMed
Foster, W. D. (1965). A History of Parasitology. Edinburgh, London: E. & S. Livingstone.Google Scholar
Galvin, T. J. (1968). Development of human and pig Ascaris in the pig and rabbit. Journal of Parasitology 54, 1085–91.CrossRefGoogle Scholar
Graham, C. F. (1941). A device for the diagnosis of Enterobius infection. American Journal of Tropical Medicine 21, 159–61.Google Scholar
Hall, A. (1981 a). Aspects of parasitic infection and host nutrition. Ph.D. Dissertation, University of Cambridge.Google Scholar
Hall, A. (1981 b). Quantitative variability of nematode egg counts in faeces: a study among rural Kenyans. Transactions of the Royal Society of Tropical Medicine and Hygiene 75, 682–7.CrossRefGoogle ScholarPubMed
Hall, A., Latham, M. C., Crompton, D. W. T. & Stephenson, L. S. (1981). Taenia saginata (Cestoda) in western Kenya: the reliability of faecal examinations in diagnosis. Parasitology 83, 91–101.CrossRefGoogle ScholarPubMed
Hall, A., Latham, M. C., Crompton, D. W. T., Stephenson, L. S. & Wolgemuth, J. C. (1982). Intestinal parasitic infections of men in four regions of rural Kenya. Transactions of the Royal Society of Tropical Medicine and Hygiene (in the Press).CrossRefGoogle Scholar
Hoagland, K. E. & Schad, G. A. (1978). Necator americanus and Ancylostoma duodenale: life history parameters and epidemiological implications of two sympatric hookworms of humans. Experimental Parasitology 44, 36–49.CrossRefGoogle ScholarPubMed
Jordan, P. & Webbe, G. (1969). Human Schistosomiasis. London: Heinemann.Google Scholar
Kannangara, D. W. W. (1975). A comparison of post-mortem analysis of helminths with faecal egg counts. Transactions of the Royal Society of Tropical Medicine and Hygiene 69, 406–9.CrossRefGoogle ScholarPubMed
Kendriok, J. R. (1934). The length of life and rate of loss of the hookworms Ancylostoma duodenale and Necator americanus. American Journal of Tropical Medicine 14, 363–79.Google Scholar
Keymer, A. (1982). Density-dependent mechanisms in the regulation of intestinal helminth populations. Parasitology 84, 573–87.CrossRefGoogle ScholarPubMed
Martin, L. K. (1965). Randomness of particle distribution in human feces and the resulting influence on helminth egg counting. American Journal of Tropical Medicine and Hygiene 14, 747–59.CrossRefGoogle ScholarPubMed
Martin, L. K. & Beaver, P. C. (1968). Evaluation of Kato thick-smear technique for quantitative diagnosis of helminth infections. American Journal of Tropical Medicine and Hygiene 17, 382–91.CrossRefGoogle ScholarPubMed
Melvin, D. M., Saudun, E. H. & Heimlich, C. R. (1956). Comparison of the direct smear and dilution egg counts in the quantitative determination of hookworm infections. American Journal of Hygiene 64, 139–48.Google Scholar
Mello, D. A. (1974). A note on egg production of Ascaris lumbricoides. Journal of Parasitology 60, 380–1.CrossRefGoogle ScholarPubMed
Muller, R. (1975). Worms and Disease: A Manual of Medical Helminthology. London: Heinemann.Google Scholar
Palmer, E. D. (1955). Course of egg output over a 15-year period in a case of experimentally induced necatoriasis americanus, in the absence of hyperinfection. American Journal of Tropical Medicine and Hygiene 4, 756–7.CrossRefGoogle Scholar
Pamba, H. O. & Mulega, P. C. (1981). Comparison of Kato thick smear technique and formol–ether sedimentation method for qualitative diagnosis of intestinal helminths. East African Medical Journal 58, 95–100.Google ScholarPubMed
Pawlowski, Z. & Schultz, M. G. (1972). Taeniasis and cysticercosis (Taenia saginata). In Advances in Parasitology, vol. 10 (ed. Dawes, B.), pp. 269–343. New York, London: Academic Press.Google Scholar
Peters, W. & Gilles, H. M. (1977). A Colour Atlas of Tropical Medicine and Parasitology. London: Wolfe.Google Scholar
Sawitz, W. (1942). The buoyancy of certain nematode eggs. Journal of Parasitology 28, 95–102.CrossRefGoogle Scholar
Schad, G. A. (1977). The role of arrested development in the regulation of nematode populations. In Regulation of Parasite Populations (ed. Esch, G. W.), pp. 111–67. New York, London: Academic Press.Google Scholar
Schad, G. A., Chowdhury, A. B., Dean, C. G., Kochar, V. K., Nawalinski, T. A., Thomas, J. & Tonascia, J. A. (1973). Arrested development in human hookworm infections: an adaptation to a seasonally unfavourable external environment. Science 180, 502–4.CrossRefGoogle ScholarPubMed
Scott, J. A. & Headlee, W. H. (1938). Studies in Egypt on the correction of helminth egg count data for size and consistency of stools. American Journal of Hygiene 27, 176–95.Google Scholar
Sehgal, S. C., Vinyak, V. K. & Gupta, U. (1977). Evaluation of Kato thick smear technique for the detection of helminthic ova in faeces. Indian Journal of Medical Research 65, 509–12.Google ScholarPubMed
Stephen, A. M. & Cummings, J. H. (1980 a). The microbial contribution to human faecal mass. Journal of Medical Microbiology 13, 45–56.CrossRefGoogle ScholarPubMed
Stephen, A. M. & Cummings, J. H. (1980 b). Mechanism of action of dietary fibre in the human colon. Nature 283, 283–4.CrossRefGoogle Scholar
Stephenson, L. S. (1980). The contribution of Ascaris lumbricoides to malnutrition in children. Parasitology 81, 221–33.CrossRefGoogle Scholar
Stoll, N. R. (1923). Investigations on the control of hookworm disease. XVIII. On the relationship between the number of eggs found in human feces and the number of hookworms in the host. American Journal of Hygiene 3, 156–79.Google Scholar
Stoll, N. R. (1947). This wormy world. Journal of Parasitology 33, 1–18.Google ScholarPubMed
Stoll, N. R. (1951). Diagnosis of intestinal helminths and protozoa: current perspective. In Parasitic Infections in Man, ed. Most, H., pp. 56–75. New York: Columbia University Press.Google Scholar
Thienpoint, D., Rochette, F. & Vanparijs, O. F. J. (1979). Diagnosing Helminthiasis through Coprologocal Examination. Belgium: Jansen Research Foundation.Google Scholar
Truelove, S. C. (1966). Movements of the large intestine. Physiological Reviews 46, 457–512.CrossRefGoogle ScholarPubMed
Wamba, J. R. (1974). Intestinal obstruction in Kenya. East African Journal of Medical Research 1, 265–72.Google Scholar
WHO (1967). Control of Ascariasis. World Health Organization Technical Report Series, no. 379. Geneva: World Health Organization.Google Scholar