Université de Fribourg

Converging seasonal prevalence dynamics in experimental epidemics

Lass, Sandra ; Hottinger, Jürgen W. ; Fabbro, Thomas ; Ebert, Dieter

In: BMC Ecology, 2011, vol. 11, p. 14

Background Regular seasonal changes in prevalence of infectious diseases are often observed in nature, but the mechanisms are rarely understood. Empirical tests aiming at a better understanding of seasonal prevalence patterns are not feasible for most diseases and thus are widely lacking. Here, we set out to study experimentally the seasonal prevalence in an aquatic host-parasite system. The...

Université de Fribourg

Apparent seasonality of parasite dynamics: analysis of cyclic prevalence patterns

Lass, Sandra ; Ebert, Dieter

In: Proceedings of the Royal Society B: Biological Sciences, 2006, vol. 243, no. 1583, p. 199-206

Seasonal disease dynamics are common in nature, but their causes are often unknown. Our case study provides insight into the cyclic prevalence pattern of the horizontally and vertically transmitted microsporidium Octosporea bayeri in its Daphnia magna host. Data from several populations over a four year period revealed a regular prevalence increase during summer and a decrease over...

Université de Fribourg

Different mechanisms of transmission of the microsporidium Octosporea bayeri: a cocktail of solutions for the problem of parasite permanence

Vizoso, Dita B. ; Lass, Sandra ; Ebert, Dieter

In: Parasitology, 2005, vol. 130, p. 501

Periods of low host density impose a constraint on parasites with direct transmission, challenging their permanence in the system. The microsporidium Octosporea bayeri faces such constraint in a metapopulation of its host, the cladoceran Daphnia magna, where ponds frequently lose their host population due to ponds drying out in summer and freezing in winter. We conducted experiments aimed to...

Université de Fribourg

Hatching with the enemy: Daphnia diapausing eggs hatch in the presence of fish kairomones

Lass, Sandra ; Vos, Matthijs ; Wolinska, Justyna ; Spaak, Piet

In: Chemoecology, 2005, vol. 15(1), p. 7

Infochemicals are known to play a key role in mediating predator-prey interactions, both in aquatic and terrestrial communities. However, state-dependent variation may exist in how effectively individuals can use this information, depending on genotype, life stage and experience. For our study, we used the predator-prey model system fish-waterflea Daphnia magna Straus (Cladocera,...