Mathematical Models of Schistosomiasis: Report of a Workshop

Pe, Fine; Lehman, Jr Js

doi:10.4269/ajtmh.1977.26.500

Cited by 12 publications

(1 citation statement)

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“…17 These points have been used to explain discrepancies between the snail infection rates predicted by theory and those observed in the field. [18][19][20] However, detailed data on prepatency in field snails have not been available because the available detection methods, including snail crushing in search of larvae and repeated shedding in the laboratory, 21 are unsuitable for accurate and large-scale monitoring.…”

Section: Introductionmentioning

confidence: 99%

Large-Scale, Polymerase Chain Reaction–based Surveillance of Schistosoma Haematobium Dna in Snails From Transmission Sites in Coastal Kenya: A New Tool for Studying the Dynamics of Snail Infection

Hamburger¹,

Hoffman²,

Kariuki³

et al. 2004

The American Journal of Tropical Medicine and Hygiene

104

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Levels of prepatent Schistosoma haematobium infection were monitored in intermediate host snails (Bulinus nasutus) collected from transmission sites in coastal Kenya, using a polymerase chain reaction (PCR) assay amplifying the Dra I repeated sequence of S. haematobium. The timing and number of prepatent and patent infections were determined for each site and, where the time of first appearance was clear, the minimal prepatent period was estimated to be five weeks. High, persistent, prepatency rates (range = 28-54%), indicated a significant degree of repeated area contamination with parasite ova. In contrast, rates of cercarial shedding proved locally variable, and were either low (range = 0.14-3.4%) or altogether absent, indicating that only a small proportion of infected snails reach the stage of cercarial shedding. Given the apparently strong focal effects of environmental conditions, implications of these new data are discussed regarding the estimation of local force of transmission and the design of control activities.

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