Suitability of red fox (Vulpes vulpes) and golden jackal (Canis aureus) as hosts of Echinococcus multilocularis based on egg production characteristics and literature data on the intestinal ecosystems of carnivores

Echinococcus multilocularis is the most important food-borne parasite in Europe. Its natural definitive host is the red fox (Vulpes vulpes) while other canid species play a secondary role in the maintenance of its endemics. However, recent studies call attention to the potential of golden jackal (Canis aureus) as a suitable definitive host for E. multilocularis. Our study aimed to evaluate the quantitative and qualitative egg production traits of adult E. multilocularis in different hosts as an indicator of reproductive success. Investigation of 111 and 82 parasites from 33 red foxes and 29 golden jackals, respectively, we ascertained that the proportion of worms with mature eggs was significantly lower in golden jackals than in red foxes. Those worms, which produced mature eggs in golden jackal hosts, originated from less crowded infrapopulations than their fox-originated counterparts. Other characteristics of the parasite's reproductive ability, such as the proportion of fertile worms, and mean egg production were similar in the two hosts. Comparing these findings to evolutionary data on different canid taxa, we hypothesised that the mutual presence of red fox and a differently evolved host of E. multilocularis might contribute to the formation of stable parasite circulation in these multi-host systems.