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A quantitative framework for evaluating the effect of community treatment on the morbidity due to ascariasis

Published online by Cambridge University Press:  06 April 2009

G. F. Medley ,
H. L. Guyatt  and
D. A. P. Bundy
G. F. Medley
Affiliation:
Wellcome Trust Centre for Research into Parasitic Infections, Imperial College of Science, Technology and Medicine, London SW7 2BB
H. L. Guyatt
Affiliation:
Wellcome Trust Centre for Research into Parasitic Infections, Imperial College of Science, Technology and Medicine, London SW7 2BB
D. A. P. Bundy
Affiliation:
Wellcome Trust Centre for Research into Parasitic Infections, Imperial College of Science, Technology and Medicine, London SW7 2BB
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Summary

There is growing emphasis on the use of community treatment to reduce the level of morbidity caused by helminth infection. The design of chemotherapy programmes, in terms of frequency of treatment and proportion of the community treated, would be assisted by a quantitative framework which enabled the morbidity reduction achieved by different approaches to be compared. The present study describes a model developed for this purpose which embodies two innovative features. First, a quantitative score of morbidity (the proportion of individuals harbouring an intense infection) is used to rate the success of a programme and, second, the distribution of helminths in the host population is generated by a mechanism that allows the distribution to change dynamically as a function of both treatment and reinfection. The model behaviour, using values typical of Ascaris lumbricoides, indicates that the benefit derived from community chemo- therapy increases non-linearly with the coverage and efficacy of treatment.

Keywords

geohelminthsepidemiologymass chemotherapyAscaris lumbricoidesmathematical models.
Type
Research Article
Information
Parasitology , Volume 106 , Issue 2 , February 1993 , pp. 211 - 221
Copyright
Copyright © Cambridge University Press 1993

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References

REFERENCES

Anderson, R. M. (1980). The dynamics and control of direct life-cycle helminth parasites. Lecture Notes in Biomathematics 39, 278–322.CrossRefGoogle Scholar
Anderson, R. M. (1982). Population dynamics and control of hookworm and roundworm infections. In Population Dynamics of Infectious Diseases: Theory and Applications (ed. Anderson, R. M.), pp. 67–108. London: Chapman and Hall.CrossRefGoogle Scholar
Anderson, R. M. & May, R. M. (1982). Population dynamics of human helminth infections: control by chemotherapy. Nature, London 297, 557–63.CrossRefGoogle ScholarPubMed
Anderson, R. M. & May, R. M. (1985). Helminth infections of humans: mathematical models, population dynamics and control. Advances in Parasitology 24, 1–101.CrossRefGoogle ScholarPubMed
Anderson, R. M. & May, R. M. (1991). Infectious Diseases of Humans: Dynamics and Control. Oxford: Oxford University Press.CrossRefGoogle Scholar
Anderson, R. M. & Medley, G. F. (1985). Community control of helminth infections of man by mass and selective chemotherapy. Parasitology 90, 629–60.CrossRefGoogle Scholar
Bailey, N. T. J. (1964). The Elements of Stochastic Processes. New York: John Wiley & Sons.Google Scholar
Bundy, D. A. P. (1990). New initiatives in the control of helminths. Transactions of the Royal Society of Tropical Medicine and Hygiene 84, 467–8.CrossRefGoogle ScholarPubMed
Bundy, D. A. P., Cooper, E. S., Thompson, D. E., Didier, J. M. & Simmons, I. (1987). Epidemiology and population dynamics of Ascaris lumbricoides and Trichuris trichiura in the same community. Transactions of the Royal Society of Tropical Medicine and Hygiene 81, 987–93.CrossRefGoogle ScholarPubMed
Bundy, D. A. P. & Medley, G. F. (1992). Immuno-epidemiology of human geohelminthiasis: ecological and immunological determinants of worm burden. Parasitology 104, S105–S119.CrossRefGoogle ScholarPubMed
Chai, J. Y., Kim, K. S., Hong, S. T., Lee, S. H. & Seo, B. S. (1985). Prevalence, worm burden and other epidemiological parameters of Ascaris lumbricoides infection in rural communities in Korea. Korean Journal of Parasitology 23, 241–6.CrossRefGoogle ScholarPubMed
Croll, N. A., Anderson, R. M., Gyorkos, T. W. & Ghadirian, E. (1980). 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
Dietz, K. (1982). Overall population patterns in the transmission cycle of infectious disease agents. In Population Biology of Infectious Diseases (ed. Anderson, R. M. & May, R. M.), pp. 87–102. Dahlem Konferenzen 1982. Springer-Verlag.CrossRefGoogle Scholar
Elkins, D. B., Haswell-Elkins, M. R. & Anderson, R. M. (1986). The epidemiology and control of intestinal helminths in the Pulicat Lake region of Southern India. I. Study design and pre- and post-treatment observations onAscaris lumbricoides infection. Transactions of the Royal Society of Tropical Medicine and Hygiene 80, 774–92.CrossRefGoogle Scholar
Guyatt, H. L. & Bundy, D. A. P. (1991). Estimating prevalence of community morbidity due to intestinal helminths: prevalence of infection as an indicator of the prevalence of disease. Transactions of the Royal Society of Tropical Medicine and Hygiene 85, 778–82.CrossRefGoogle ScholarPubMed
Guyatt, H. L., Bundy, D. A. P., Medley, G. F. & Grenfell, B. T. (1990). The relationship between the frequency distribution of Ascaris lumbricoides and the prevalence and intensity of infection in human communities. Parasitology 101, 139–43.CrossRefGoogle ScholarPubMed
Hadeler, K. p. & Dietz, K. (1983). Non-linear hyperbolic partial differential equations for the dynamics of parasite populations. Comparative Mathematics and Applications 9, 415–30.CrossRefGoogle Scholar
Haswell-Elkins, M. R., Elkins, D. B. & Anderson, R. M. (1987). Evidence for predisposition in humans to infections with Ascaris, hookworm, Enterobius and Trichuris in a South Indian fishing community. Parasitology 95, 323–37.CrossRefGoogle Scholar
Keymer, A. E. & Pagel, M. (1990). Predisposition to hookworm infection. In Hookworm Infection: Current Status and New Directions (ed. Schad, G. A. & Warren, K. S.). London: Taylor and Francis.Google Scholar
Keymer, A. E. & Slater, A. F. G. (1987). Helminth fecundity: density dependence of statistical illusion? Parasitology Today 3, 56–8.CrossRefGoogle ScholarPubMed
Lwambo, N. J. S., Bundy, D. A. P. & Medley, G. F. H. (1992). A new approach to morbidity risk assessment in hookworm endemic communities. Epidemiology and Infection 108, 469–81.CrossRefGoogle ScholarPubMed
McCallum, H. I. (1990). Covariance in parasite burdens: the effect of predisposition to infection. Parasitology 100, 153–9.CrossRefGoogle ScholarPubMed
Martin, J., Keymer, A. E., Isherwood, R. J. & Wainwright, S. M. (1983). The prevalence and intensity of Ascaris lumbricoides infections in Moslem children from northern Bangladesh. Transactions of the Royal Society of Tropical Medicine and Hygiene 77, 702–6.CrossRefGoogle ScholarPubMed
Nag (1990). The NAG Fortran Library Manual, Mark 14. Numerical Algorithms Group Limited.Google Scholar
Prescott, N. M. (1987). The economics of schistosomiasis chemotherapy. Parasitology Today 3, 21–5.CrossRefGoogle ScholarPubMed
Quinnell, R. J., Medley, G. F. & Keymer, A. E. (1990). The regulation of gastro-intestinal helminth populations. Proceedings of the Royal Society of London, 330B, 191–201.Google Scholar
Rosenfield, P. L., Smith, R. A. & Wolman, M. G. (1977). Development and verification of a schistosomiasis transmission model. American Journal of Tropical Medicine and Hygiene 26, 505–16.CrossRefGoogle ScholarPubMed
Schad, G. A. & Anderson, R. M. (1985). Predisposition to hookworm infection in humans. Science 228, 1537–40.CrossRefGoogle ScholarPubMed
Thein-Hlaing, , Than-Saw, , Htay-Htay-Age, , Myint-Lwin, & Thein-Maung-Myint, (1984). Epidemiology and transmission dynamics of Ascaris lumbricoides in Okpo village, rural Burma. Transactions of the Royal Society of Tropical Medicine and Hygiene 78, 497–504.CrossRefGoogle ScholarPubMed
Thein-Hlaing, , Than-Saw, & Myat-Lay-Kyin, (1991). The impact of three-monthly age-targetted chemotherapy on Ascaris lumbricoides infection. Transactions of the Royal Society of Tropical Medicine and Hygiene 85, 519–22.CrossRefGoogle ScholarPubMed
Warren, K. S., Bundy, D. A. P., Anderson, R. M., Davies, A. R., Henderson, D. A., Jamison, D. T., Prescott, N. & Senft, A. (1990). Helminth infections. In Disease and Disease Control in Developing Countries (ed. Jamison, D. T. & Mosley, W. H.). Washington DC: World Bank. (In the Press.)Google Scholar
Weimer, C. (1987). Optimal disease control through combined use of preventive and curative measures. Journal of Developmental Economics 25, 301–19.CrossRefGoogle Scholar