ANGIOSTRONGYLUS CANTONESIS: HOST POPULATION DYNAMICS AND THE INFLUENCE OF SEASONALITY

Abstract

The aim of this paper is to determine the dynamics of Angiostrongylus cantonensis in its host populations, focusing particularly on the effects of seasonality. Fieldwork in Jamaica, noting a decreased prevalence of A. cantonensis in the test species Thelidomus Aspera, culminated in a hypothesis that seasonality influences prevalence. Specifically, prevalence drops during the dry season. An SI model was created to describe rat lungworm dynamics first without and then with seasonality. The first model illustrates the stability of this parasite’s life cycle, which requires few definitive hosts to maintain significant prevalence in a system. It also indicates that areas of human disturbance are likely to carry higher prevalence. This model also provides evidence showing that infection from rats to snail by means of infected snail mucus and by means of consumption of the snail yield similar equilibriums. This provides evidence supporting the possibility of infection through consumption of snail mucus even though no study has yet to detect larvae in this medium. Finally seasonality was added using cosine function to simulate the wet and dry seasons of tropical environments. Simulations of this model show that snail populations are impacted more significantly by seasonality. This model also seems to reject the initial hypothesis developed based on fieldwork. In almost all cases prevalence of infection in the snail was higher during the dry season. At very high contact rates or transmissions rates prevalence seemed to shift toward the wet season.