Natural Infection of the Ground Squirrel (Spermophilus spp.) with Echinococcus granulosus in China

Echinococcus granulosus and E. multilocularis are important zoonotic pathogens that cause serious disease in humans. E. granulosus can be transmitted through sylvatic cycles, involving wild carnivores and ungulates; or via domestic cycles, usually involving dogs and farm livestock. E. multilocularis is primarily maintained in a sylvatic life-cycle between foxes and rodents. As part of extensive investigations that we undertook to update available epidemiological data and to monitor the transmission patterns of both E. granulosus and E. mulilocularis in Ningxia Hui Autonomous Region (NHAR) in northwest China, we captured small mammals on the southern slopes of Yueliang Mountain, Xiji, an area co-endemic for human alveolar echinococcosis and cystic echinococcosis. Of 500 trapped small mammals (mainly ground squirrels; Spermophilus dauricus/alashanicus), macroscopic cyst-like lesions (size range 1–10 mm) were found on the liver surface of approximately 10% animals. One of the lesions was shown by DNA analysis to be caused by E. granulosus and by histology to contain viable protoscoleces. This is the first report of a natural infection of the ground squirrel with E. granulosus. We have no definitive proof of a cycle involving ground squirrels and dogs/foxes but it is evident that there is active E. granulosus transmission occurring in this area

Support for targeted sampling of red fox (Vulpes vulpes) feces in Sweden: a method to improve the probability of finding Echinococcus multilocularis

BACKGROUND: Localized concentrations of Echinococcus multilocularis eggs from feces of infected red fox (Vulpes vulpes) can create areas of higher transmission risk for rodent hosts and possibly also for humans; therefore, identification of these areas is important. However, in a low prevalence environment, such as Sweden, these areas could be easily overlooked. As part of a project investigating the role of different rodents in the epidemiology of E. multilocularis in Sweden, fox feces were collected seasonally from rodent trapping sites in two regions with known parasite status and in two regions with unknown parasite status, 2013–2015. The aim was to evaluate background contamination in rodent trapping sites from parasite eggs in these regions. To maximize the likelihood of finding fox feces positive for the parasite, fecal collection was focused in habitats with the assumed presence of suitable rodent intermediate hosts (i.e. targeted sampling). Parasite eggs were isolated from feces through sieving-flotation, and parasite species were then confirmed using PCR and sequencing. RESULTS: Most samples were collected in the late winter/early spring and in open fields where both Arvicola amphibius and Microtus agrestis were captured. Fox feces positive for E. multilocularis (41/714) were found within 1–3 field collection sites within each of the four regions. The overall proportion of positive samples was low (≤5.4%) in three regions, but was significantly higher in one region (22.5%, P < 0.001). There was not a significant difference between seasons or years. Compared to previous national screenings, our sampling strategy identified multiple E. multilocularis positive feces in all four regions, including the two regions with previously unknown parasite status. CONCLUSIONS: These results further suggest that the distribution of E. multilocularis is highly aggregated in the environment and provide support for further development of a targeted sampling strategy. Our results show that it was possible to identify new areas of high contamination in low endemic environments. After further elaboration, such a strategy may be particularly useful for countries designing surveillance to document freedom from disease. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1897-3) contains supplementary material, which is available to authorized users

Predator dietary response to prey density variation and consequences for cestode transmission

The functional response of predators to prey density variations has previously been investigated in order to understand predation patterns. However, the consequences of functional response on parasite transmission remain largely unexplored. The rodents Microtus arvalis and Arvicola terrestris are the main prey of the red fox Vulpes vulpes in eastern France. These species are intermediate and definitive hosts of the cestode Echinococcus multilocularis. We explored the dietary and contamination responses of the red fox to variations in prey density. The dietary response differed between the two prey species: no response for M. arvalis and a type III-like (sigmoidal) response for A. terrestris that shows possible interference with M. arvalis. The fox contamination response followed a type II shape (asymptotic) for both species. We conclude that fox predation is species specific and E. multilocularis transmission is likely to be regulated by a complex combination of predation and immunologic factors. These results should provide a better understanding of the biological and ecological mechanisms involved in the transmission dynamics of trophically transmitted parasites when multiple hosts are involved. The relevance of the models of parasite transmission should be enhanced if non-linear patterns are taken into account