Trophic ecology, behaviour and host population dynamics in Echinococcus multilocularis transmission

Abstract

The life cycle of the cestode Echinococcus multilocularis primarily involves canids and small mammals (rodents, lagomorphs) as definitive and intermediate hosts, respectively. Several surveys have identified marked temporal and geographical variations at different scales in the parasite's prevalence in both types of hosts, suggesting variations in the biological and ecological factors that control transmission processes. The parasite transmission from intermediate to definitive hosts is determined by the predator-prey relationship, which theoretically depends on prey population dynamics and the complex dietary response of predators to varying densities of prey species and other food items. Parasite eggs are transmitted to intermediate hosts via carnivore faeces, whose distribution in the environment is driven by the defecating behaviour of final hosts. We reviewed field-based studies that address issues related to the trophic ecology and behaviour of definitive hosts, interactions between definitive and intermediate hosts, and E. multilocularis transmission both in wild and domestic animals in rural and urban environments. Two density-dependent mechanisms control the transmission dynamics in definitive hosts: one is based on the variations in the availability of intermediate hosts, and the other is based on the variations in the density of the definitive host and its faeces. Non-linearity and the direct and delayed responses of definitive host contamination in relation to intermediate host population variations were recorded. The dietary response of the red fox was shown to be complex when abundant alternative resources were available (anthropogenic food, multiple intermediate host prey species). Micro-local hotspots of parasite transmission to intermediate hosts in a landscape, as well as areas of higher risk for human contamination in village and urban settings, may be explained by the definitive hosts' activity patterns and defecation behaviour.

Global Distribution of Alveolar and Cystic Echinococcosis

“…For the situation in the European part of the Russian Federation, see Section 3.3.1. s0035 2.2.1 Central Europe: France, Belgium, The Netherlands, Luxembourg, Germany, Switzerland, Czech Republic, Austria, Northern Italy s0040 2.2.1.1 Transmission and host assemblages p0100 Transmission of E. multilocularis in the 'old' endemic area of Central Europe is mainly based on the red fox as definitive host and voles (Microtus arvalis and Arvicola spp.) as intermediate hosts (Raoul et al, 2015), see chapter: Ecology and Life Cycle Patterns of Echinococcus Species by Romig et al (2017). p0105…”

“…Transmission of E. multilocularis is determined by host ecology (such as predatoreprey preferences, defecating behaviour, activity patterns of definitive hosts and host dietary preferences). Key intermediate hosts have been identified for only central study areas in Europe and on Svalbard Island (Raoul et al, 2015); for most of the other areas there are insufficient data concerning rodent population composition and predation by definitive hosts. Therefore, it is difficult to understand the transmission patterns or predict changes in parasite abundance or distribution (such as range expansion).…”

“…For reviews, see [Raoul et al, 2015;chapter: Ecology and Life Cycle Patterns of Echinococcus Species by Romig et al (2017)]. 2.2.1.1.1 Infections in animals In large parts of Central Europe, E. multilocularis is present in red fox populations with average prevalences ranging between 0.1% and 50% (Fig.…”

“…Schantz et al (1995) reported a trend for prevalence to increase over time, but this is greatly influenced by study design and may change dramatically with new molecular techniques for coprodiagnosis. Prevalence varies seasonally, with reports lowest in winter and highest in summer in red fox in North Dakota (Kritsky and Leiby, 1978) and highest in autumn and lowest in spring in Arctic foxes on St. Lawrence Island (Rausch and Fay, 2002). There are also geographic differences.…”

“…In a highly endemic island system (St. Lawrence Island), 5e13% of dogs were positive for E. multilocularis on examination of intestines at necropsy (Rausch and Fay, 2002), and dogs were considered the primary source of human exposure to the parasite (Stehr-Green et al, 1988). Outside Alaska, neither adult cestodes nor eggs of E. multilocularis have been reported from dogs in North America.…”