Infectious disease agents mediate interaction in food webs and ecosystems.

Infectious agents are part of food webs and ecosystems via the relationship with their host species that, in turn, interact with both hosts and non-hosts. Through these interactions, infectious agents influence food webs in terms of structure, functioning and stability. The present literature shows a broad range of impacts of infectious agents on food webs, and by cataloguing that range, we worked towards defining the various mechanisms and their specific effects. To explore the impact, a direct approach is to study changes in food-web properties with infectious agents as separate species in the web, acting as additional nodes, with links to their host species. An indirect approach concentrates not on adding new nodes and links, but on the ways that infectious agents affect the existing links across host and non-host nodes, by influencing the 'quality' of consumer-resource interaction as it depends on the epidemiological state host involved. Both approaches are natural from an ecological point of view, but the indirect approach may connect more straightforwardly to commonly used tools in infectious disease dynamics.

First findings and prevalence of adult heartworms (Dirofilaria immitis) in wild carnivores from Serbia.

Heartworm (Dirofilaria immitis) is a parasitic roundworm that causes a zoonotic disease known as dirofilariosis. Little is known about the role of wild carnivores serving as reservoirs in nature. Therefore, we examined 738 hearts and lungs of free ranging wild carnivores from Serbia to determine the presence of adult heartworms. During the period 2009-2013, the prevalence in golden jackals (Canis aureus) was 7.32%, in red foxes (Vulpes vulpes) 1.55%, in wolves (Canis lupus) 1.43%, and in wild cats (Felis silvestris) 7.69%. No adult heartworm specimens were found in beech martens (Martes foina), stone martens (Martes martes), European polecats (Mustela putorius), badgers (Meles meles) or otter (Lutra lutra). The highest recorded prevalence was in 2013 (7.30%) and the lowest in 2012 (1.6%). In jackals, the prevalence was higher in males (10%) than in females (4.06%), while in foxes the prevalence was 1.75% in males and 1.26% in females. The most infected host was a wolf in which 37 adult specimens were found. Because of the potentially significant role in the life cycle of D. immitis, populations of wild carnivores in Europe should be further examined and tested for heartworm infections.

Ecological multiplex interactions determine the role of species for parasite spread amplification.

Despite their potential interplay, multiple routes of many disease transmissions are often investigated separately. As a unifying framework for understanding parasite spread through interdependent transmission paths, we present the 'ecomultiplex' model, where the multiple transmission paths among a diverse community of interacting hosts are represented as a spatially explicit multiplex network. We adopt this framework for designing and testing potential control strategies for Trypanosoma cruzi spread in two empirical host communities. We show that the ecomultiplex model is an efficient and low data-demanding method to identify which species enhances parasite spread and should thus be a target for control strategies. We also find that the interplay between predator-prey and host-parasite interactions leads to a phenomenon of parasite amplification, in which top predators facilitate T. cruzi spread, offering a mechanistic interpretation of previous empirical findings. Our approach can provide novel insights in understanding and controlling parasite spreading in real-world complex systems.