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Adv Parasitol. 2015 Mar;87:193-247. doi: 10.1016/bs.apar.2015.01.001. Epub 2015 Feb 14.

Mathematical inference on helminth egg counts in stool and its applications in mass drug administration programmes to control soil-transmitted helminthiasis in public health.

Author information

1
Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
2
Imperial College London, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health St Mary's Campus, Norfolk Place, London, UK.
3
Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
4
Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium; Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium.
5
Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium.
6
Department of Applied Mathematics, Computer Science and Statistics, Faculty of Sciences, Ghent University, Ghent, Belgium; Department of Mathematics, Faculty of Sciences, KU Leuven University, Leuven, Belgium.

Abstract

In the present study, we present a hierarchical model based on faecal egg counts (FECs; expressed in eggs per 1g of stool) in which we first describe the variation in FECs between individuals in a particular population, followed by describing the variance due to counting eggs under a microscope separately for each stool sample. From this general framework, we discuss how to calculate a sample size for assessing a population mean FEC and the impact of an intervention, measured as reduction in FECs, for any scenario of soil-transmitted helminth (STH) epidemiology (the intensity and aggregation of FECs within a population) and diagnostic strategy (amount of stool examined (∼sensitivity of the diagnostic technique) and examination of individual/pooled stool samples) and on how to estimate prevalence of STH in the absence of a gold standard. To give these applications the most wide relevance as possible, we illustrate each of them with hypothetical examples.

KEYWORDS:

Anthelminthic resistance; Faecal egg counts; Hierarchical model; Mass drug administration; Monitoring system; Sample size; Soil-transmitted helminths; Survey design; True prevalence

PMID:
25765196
DOI:
10.1016/bs.apar.2015.01.001
[Indexed for MEDLINE]

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