title: A further model for temporal patterns in the epidemiology of schistosome infections of snails.
abstract: The prevalence of Schistosoma mansoni infections of Biomphalaria pfeifferi shows seasonal variation. Field data from Zimbabwe show annual ranges from 0 to 7%. In this paper a mathematical model of B. pfeifferi population dynamics and S. mansoni epidemiology is used as a framework for analysis of these patterns. Snail fecundity is a function of snail age and of temperature, and is apparently affected by other seasonal factors. The pre-patent period is dependent on temperature. Infection affects snail fecundity and mortality. Parameter values are derived from previous field and laboratory studies. The force-of-infection is estimated from the analysis of size-prevalence data. Using observed temperatures, model output agrees well with field data on snail abundance and prevalence of infection over a 14-month period. Seasonal variation in prevalence largely reflects variation in the pre-patent period and in snail population age structure. The possible role of seasonality in the force-of-infection is discussed. Prevalence patterns are not greatly affected by year-to-year differences in temperature. Significant seasonal variation in snail-man transmission rates is expected.
authors.affiliation: Department of Zoology, University of Oxford.
authors.forename: M E
authors.initials: ME
authors.lastname: Woolhouse
authors.forename: S K
authors.initials: SK
authors.lastname: Chandiwana
mesh_terms: D000818:Animals; D001700:Biomphalaria / Q000469:parasitology*; D008954:Models, Biological; D011891:Rain; D012550:Schistosoma mansoni / Q000254:growth & development*; D012621:Seasons; D013696:Temperature; D013997:Time Factors