Nematode Parasites of Vertebrates: Their Development and Transmission

For a long time, wildlife carnivores have been disregarded for their potential in transmitting zoonotic nematodes. However, human activities and politics (e.g., fragmentation of the environment, land use, recycling in urban settings) have consistently favoured the encroachment of urban areas upon wild environments, ultimately causing alteration of many ecosystems with changes in the composition of the wild fauna and destruction of boundaries between domestic and wild environments. Therefore, the exchange of parasites from wild to domestic carnivores and vice versa have enhanced the public health relevance of wild carnivores and their potential impact in the epidemiology of many zoonotic parasitic diseases. The risk of transmission of zoonotic nematodes from wild carnivores to humans via food, water and soil (e.g., genera Ancylostoma, Baylisascaris, Capillaria, Uncinaria, Strongyloides, Toxocara, Trichinella) or arthropod vectors (e.g., genera Dirofilaria spp., Onchocerca spp., Thelazia spp.) and the emergence, re-emergence or the decreasing trend of selected infections is herein discussed. In addition, the reasons for limited scientific information about some parasites of zoonotic concern have been examined. A correct compromise between conservation of wild carnivores and risk of introduction and spreading of parasites of public health concern is discussed in order to adequately manage the risk of zoonotic nematodes of wild carnivores in line with the 'One Health' approach.

https://www.zora.uzh.ch/id/eprint/175913/1/Ortanto_et_al.%2C_Parasites_and_Wildlife_9%282019%29_1332.pdf

Zoonotic nematodes of wild carnivores.

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future.

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Challenges and science-based implications for modern management and conservation of European ungulate populations

There are many different factors involved in parasitism. The general concept of “filters” proposed by Combes includes “encounter filters” (behavior, biodiversity) and “compatibility filters” (resources, defense) to explain mechanisms responsible for the formation of host–parasite coexistence. However, researches explaining the reasons for the spread and dynamics of parasites in populations of wild terrestrial mammals in Europe and the specific factors affecting prevalence and intensity of parasitosis are limited. Many factors, ecological, biological, and anthropogenic, form a complex network of interdependencies that shape this pattern. Here, I summarize the current state of knowledge on the factors affecting parasitic diseases in wild mammals inhabiting the European continent. It indicates the need to further development, not only for academic reasons, but also for the benefit of use in management of wild mammal species and disease control in nature.

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Factors affecting the spread of parasites in populations of wild European terrestrial mammals

Anthropogenic food subsidies hinder the ecological role of wolves: Insights for conservation of apex predators in human-modified landscapes

Coevolved species should avoid competition through resource partitioning, but human-induced alteration of plant/animal communities may facilitate the onset of competitive interactions. In herbivores, access to high-quality forage in the warm months, that is, during nursing and weaning, influences growth and survival of offspring. In turn, resource exploitation by a reintroduced, superior competitor should affect offspring survival of the inferior one, by decreasing foraging efficiency and diet quality of mothers and young. We assessed the negative effects of reintroduced red deer Cervus elaphus on grassland, on foraging behavior of female Apennine chamois Rupicapra pyrenaica ornata (July–October 2012–2013) and on winter survival of chamois kids, across 3 study sites with different deer densities (great/intermediate/extremely low). The size of bare soil patches was positively associated with deer density and, in areas with deer, it increased throughout July–October. The volume of nutritious plants (i.e., legumes) in the diet of female chamois was lower and decreased faster between summer and autumn, in areas with deer than in that with an extremely low deer density. Feeding intensity (bite rate) of female chamois was significantly lower and their food searching (step rate) was greater in areas with deer. Chamois kids showed a significantly greater winter mortality, with a lower proportion of younger individuals, in areas with deer than in that with an extremely low deer density. In human-altered ecosystems, unpredictable consequences can follow interspecific interactions within restored animal communities. In turn, patterns of ecological relationships among ecosystem components may be modified, with an increase of the potential for competitive interactions.

Competition between wild herbivores: reintroduced red deer and Apennine chamois

Wildcats are endangered felid species living in Europe, Asia, and Africa. Regrettably, scientific information on parasites of wildcats is particularly meager and they often rely on data gained by necropsies of a small number of animals. In the present study, scat collection was used to assess the parasite spectrum of European wildcats living in the Etna Park (Sicily, Italy). Scat collection was performed from May to September 2010 by weekly walking four transects for a total of 391 km. Samples were then analyzed by flotation and sedimentation techniques to investigate wildcat parasitic fauna. A total of 121 scats of wildcats were collected, and parasitic forms (i.e., oocysts, eggs, and larvae) were retrieved in 110 (90.9 %) of the samples. Parasites found were Physaloptera sp. (52.1 %), tapeworms (45.5 %), Toxocara cati (43.8 %), Eucoleus aerophilus (27.3 %), Ancylostoma sp. (22.3 %), Troglostrongylus brevior (15.7 %), trematodes (9.9 %), Isospora felis (4.1 %), Cylicospirura sp. (1.7 %), and Acanthocephala (0.8 %). The prevalence of endoparasitic infections herein recorded is similar to that described in other studies conducted using necropsy technique. The species richness of parasites found in the present survey, with a total of nine helminths and one protozoon, is the highest ever reported for wildcat in Europe. Scat collection and examination are reliable and rapid non-invasive tools which can be used in a systematic survey design to study the parasite spectrum of wildcat as well as that of other endangered wild species.

Survey on parasitic infections in wildcat (Felis silvestris silvestris Schreber, 1777) by scat collection.

Lactation exerts heavy energetic and physiological costs to mothers, whilst determining early growth and survival of offspring. To mountain ungulates, access to high-quality forage during nursing and weaning is crucial for reproductive success. We have evaluated the effects of pasture quality on suckling behaviour and winter survival of Apennine chamois Rupicapra pyrenaica ornata kids, across three areas. Areas A-B (‘poor’ areas) were characterised by a reduced availability of nutritious forage, thus a lower diet quality for female chamois and kids; Area C (a ‘rich’ area) included a much greater availability of nutritious forage. In poor areas, pasture quality has been reduced by climatic and plant composition changes, as well as the presence of a herbivore competitor (red deer Cervus elaphus). In poor areas, we recorded a significantly (1) lower suckling success of chamois kids (number of suckling bouts/number of suck attempts); (2) lower frequency of suckling bouts (n. suckling bouts/kid/h); and (3) lower suckling intensity (suck duration/kid/h) in respect to the rich area. Conversely, frequencies of suckling rejections and those of suckling attempts (n. events/kid/h) were the lowest in the rich area. Winter survival of chamois kids was c. 2 times greater in the rich area (45%) than in poor areas (20–26%). In the poor areas, resource scarcity induced adult female chamois to decrease maternal cares and favour their own maintenance, ultimately affecting population dynamics through kid winter mortality.

Pasture Quality Affects Juvenile Survival through Reduced Maternal Care in a Mountain‐Dwelling Ungulate

Abstract In mountain ungulates, antipredator behaviour is one of the main constraints on foraging behaviour and habitat selection, especially when newborn, vulnerable offspring are present. Golden eagles have been known to prey on ungulates successfully, but predation may be relatively rare on chamois. Here, we report an unsuccessful predation attempt by a golden eagle on a kid of Apennine chamois. The kid was grazing in a female kid mixed herd, and the attack by the eagle was deterred by cooperative defence of females. Chamois are a social species: defending other females’ fawns may be consistent with the importance of cooperative maternal behaviour in kin groups.

Cooperative defence of female chamois successfully deters an eagle attack

Maternal cares and, in particular, suckling behaviour, are fundamental for early growth and survival of offspring ungulates. In turn, factors influencing maternal cares can have important effects a...

Davide Scornavacca

Papers

Competition between wild herbivores: reintroduced red deer and Apennine chamois

Survey on parasitic infections in wildcat (Felis silvestris silvestris Schreber, 1777) by scat collection.

Pasture Quality Affects Juvenile Survival through Reduced Maternal Care in a Mountain‐Dwelling Ungulate

Cooperative defence of female chamois successfully deters an eagle attack

Suckling behaviour and allonursing in the Apennine chamois