Epidemiological studies on intestinal helminth parasites of the patagonian grey fox (Pseudalopex griseus) in Tierra del Fuego, Patagonia Argentina

Presence of Echinococcus granulosussensulato in the endoparasitic fauna of feral dogs in Tierra del Fuego, Argentina

The feral dog population from Tierra del Fuego (Argentina) has affected provincial sheep production, and is responsible for the decrease of 43% of the sheep stock. In addition, feral dogs preys on the native fauna, especially the guanaco (Lama guanicoe), a species protected by law. Except for some data on the aforementioned impact, very little is known about feral dogs features in this region, such as distribution, abundance, diet, reproduction, health status, among others. Therefore, a descriptive observational study was carried out in the period 2018-2021 in Tierra del Fuego, with the aim to recognize the endoparasitic fauna of these dogs, with emphasis on Echinococcus granulosus sensu lato (s.l.). Feces samples were collected from 83 feral dogs captured in 15 farms, which were evaluated using flotation and sedimentation coproparasitological techniques, and optical microscope observation. These qualitative methods showed that 66.3% of the samples were positive. Nine parasitic forms were found, including eggs of taenids, Toxocara canis and Toxascaris leonina, and Sarcocystis spp. oocysts and Giardia spp. cysts. Samples with more than one parasitic form were also observed, among which the Taenia/Sarcocystis spp. association was the most frequent. For the diagnosis of canine echinococcosis, the detection of Echinococcus spp. antigens by Copro-ELISA and the molecular confirmation by Copro-PCR were performed. The Copro-ELISA test was positive in 10/80 (12.5%) of the samples processed, while 11 samples (13.8%) were positive by Copro-PCR. Their distribution showed that 9 (81.8%) corresponded to farms with sheep farming, and 2 (18.2%) with cattle farming. The presence of E. granulosus s.l. in feral dogs from Tierra del Fuego is the most relevant finding in this study. These results confirm that feral dogs have access to viscera infected with hydatid cysts. However, the intermediate hosts involved (sheep, cattle or guanacos) should be investigated. Its impact on the transmission of cystic echinococcosis in this region should be evaluated, as well as the adequacy of the disease prevention and control actions implemented in Tierra del Fuego should be considered. Finally, the existence of a wild cycle of the disease should be evaluated, in which feral dogs would act as a source of infection for other animals and humans.

Increased prevalence of canine echinococcosis a decade after the discontinuation of a governmental deworming program in Tierra del Fuego, Southern Chile

Hydatid disease is a neglected zoonotic parasitic disease caused by cysts of the tapeworm Echinococcus granulosus. Canids, especially domestic dogs, are definitive hosts of the parasite and are the most pragmatic targets for control programs. A governmental dog deworming campaign was established in 1979 to control hydatidosis in southern Chile, which succeeded in reducing the prevalence of canine echinococcosis in Tierra del Fuego province from 68.4% (in 1978) to 1.2% (in 2002). In 2004, however, the program was dismantled to reduce costs, and since then, no follow-up echinococcosis monitoring has been conducted. We surveyed 356 domestic dogs and interviewed owners or workers at 45 ranches in Chilean Tierra del Fuego during the summer of 2015-2016. Faecal flotation was employed to detect Taeniidae eggs, and PCR was used to test faecal samples for Echinococcus granulosus. Taeniidae eggs and Echinococcus sp. DNA were detected in the faeces of 45.4% (147/324) and 6.9% (23/331) of dogs, respectively. Infrequent dog deworming and the presence of culpeo foxes (Lycalopex culpaeus) were significant predictors of the prevalence of Echinococcus sp. DNA and Taeniidae eggs. Furthermore, the presence of introduced chilla foxes (Lycalopex griseus), the municipality, and several operational characteristics of ranches (number of sheep, frequency of sheep slaughter, number of dogs, frequency of removal of dog faeces, feeding of dogs with sheep viscera) were also predictive of the prevalence of Taeniidae eggs. Our findings reveal an ongoing risk of echinococcosis with pathogen maintenance in ranch dogs in Chilean Tierra del Fuego, and in the absence of adequate control programmes, there is a tangible risk of re-emergence of hydatid disease as a public health concern.

Livestock guarding dogs have minor effects on the parasite burden of wild carnivores

Livestock guarding dogs are increasingly used to reduce carnivore-livestock conflicts, but no information is available to determine any adverse effects that these dogs may have on the health of wild carnivores. We assessed differences in prevalence, richness and severity of parasites in chilla fox (Lycalopex griseus) populations associated with livestock guarding dogs, which were routinely dewormed. We also evaluated whether the parasite assemblages of herding dogs, which were not dewormed, and chilla foxes were more similar in the presence of livestock guarding dogs. Scats of L. griseus and herding dogs were collected and screened for parasite eggs in areas with and without livestock guarding dogs to determine differences in prevalence, richness, intensity and parasite aggregation. We did not find any association between livestock guarding dogs and differences in parasite richness or prevalence of parasites. The intensity of parasites was higher among foxes positive to parasites when LGDs were present. A lower proportion of foxes with low parasite burdens occurred in areas with LGDs compared to areas without LGDs, but this difference was not significant at the population level. Our findings show the need to continue studying the effects of livestock guarding dogs on the health of wildlife with larger sample sizes and more locations.

Endoparasitic fauna of two South American foxes in Chile: Lycalopex culpaeus and Lycalopex griseus

Native foxes face serious threats related to anthropic activities and the uncontrolled pets. However, the transmission of several pathogens such as parasites by domestic dogs is an important conservation issue with limited attention in Chile. The lack of a proper identification of the helminths of wild canids in the country, based mostly in coprological studies, limited our knowledge in potential interspecific transmission. Thus, the aim of the present survey was to identify the parasitic fauna of two native canids, the Andean fox (Lycalopex culpaeus) (n=49) and Chilla (Lycalopex griseus) (n=17), from several localities in Chile through a complete parasitological survey. Sixteen different species were identified, 9 of which are new host records for Andean fox and two for Chilla fox in South America, and three are recorded for first time in Chile. Also, five of them are of zoonotic concern and six are known to use domestic dogs as their principal hosts. These findings have implications for public health and the conservation of canids whose interspecific transmission of parasites with domestic dogs is confirmed through these findings. The need for an exhaustive surveillance of wild carnivores is emphasized considering these hosts as important sources of micro- and macroparasites.

Updated checklist of helminths found in terrestrial mammals of Argentine Patagonia

The aim of the present study was to evaluate the state of knowledge about the helminthology of wild mammals in Argentine Patagonia and its link with the conservation of parasite species and biodiversity. To this end, the information included in the previously reported checklist of the helminths found in terrestrial wild mammals of Argentine Patagonia was completed and updated. The methodology used for the search was the same as that previously used, with slight modifications. Eighty-two species of mammals currently inhabit the region, and an additional six species are considered to have become extinct before the 20th century. The reports used to complete and update the information correspond to research done since 2015 to date. Considering the number of records analysed in the previously reported checklist and those of the current update, a total of 1918 helminthological reports for current Patagonian mammals and 2141 on mammal species that inhabited Patagonia before the 20th century were accounted for. It is important to point out that 41% of the 82 species of wild mammals currently inhabiting Patagonia have not been studied helminthologically; 38% of these without helminthological records are either threatened or do not have categorization, and 79% of mammals without helminthological studies have some degree of endemism. Therefore, in order to evaluate conservation priorities, the information about the parasitic richness in Patagonian wild mammals should be substantially increased, especially in those endangered or endemic.

Intestinal parasites in canine feces contaminating urban and recreational areas in Ushuaia (Argentina)

Wild and domestic dogs are important reservoir hosts of numerous intestinal parasites that represent potential infection sources for both humans and wild or other domestic animals. The aim of this study was to determine the presence, diversity, and contamination potential of intestinal parasites in dog feces contaminating urban and recreational areas in Ushuaia (Tierra del Fuego province, Argentina). A total of 80 canine fecal samples were collected from urban (playgrounds, streets, sidewalks, squares and coastal walks) and recreational areas (winter centers for raising and training sled dogs) in 2018. Samples were preserved in 5% formalin and processed using formalin-ethyl acetate sedimentation and FLOTAC dual Pellet techniques. Data were analyzed using the R software. At least one parasite species was recovered in 32.5% of the total samples examined. Of the seven parasite species detected, infection by protozoan species was higher than helminth infections (28.8% versus 8.8%). Sarcocystis sp. (20.0%), Giardia sp. (8.8%) and Cystoisospora spp. (7.5%) were the most frequent species, followed by Toxocara canis (5.0%), Echinococcus spp./Taenia spp. (2.5%), Trichuris vulpis and Uncinaria sp. (1.3% for both). Single infections (69.2%) were more frequent than coinfections with two (19.2%) and three parasite species (11.5%). This study provides the first description of the diversity and frequency of intestinal parasite species in dog feces from Ushuaia, the southernmost city in the world. The unfavorable environment of Ushuaia, characterized by low temperatures and winter snowfall, is likely to reduce parasite survivability, decreasing contamination potential. Some parasite species found are potentially zoonotic and represent an important risk for the human population and a source of infection to free-roaming pets. The results of this study revealed the need to strengthen the prevention, surveillance and control of these infections in pets, as well as to implement programs for public health education, control measures for the free-roaming canine population, and responsible pet ownership in the study area.

Reprint of "Survey and first molecular characterization of Echinococcus granulosus sensu stricto (G1) in Pampas fox (Lycalopex gymnocercus) in Buenos Aires province, Argentina"

Echinococcosis is a zoonosis caused by tapeworms of the genus Echinococcus. Echinococcus granulosus sensu lato (s. l.) has a world-wide distribution and its transmission is primarily maintained in a synanthropic cycle with dogs as definitive hosts and livestock species as intermediate hosts. However, many wild canids also function as definitive hosts for E. granulosus s. l. Echinococcosis in humans is mainly caused by E. granulosus sensu stricto (s. s.) G1 genotype. In the present work, we expanded the epidemiological study on echinococcosis reported cases in Pampas fox (Lycalopex gymnocercus) to provide a prevalence estimate for rural areas of southern Buenos Aires province, Argentina. Ninety-five whole intestines were analyzed using the sedimentation and counting technique with a result of 83 foxes (87.37%) harboring at least one helminth species. E. granulosus s. l. adults were found in one Pampas fox (1.05%). These adult helminthes were E. granulosus s. s. (G1) according to the genotyping analysis of a 450-bp region of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene.

Ancylostoma (Ancylostoma) buckleyi (Nematoda: Ancylostomatidae): new wild host and distribution expansion

Here we report the occurrence of Ancylostoma (Ancylostoma) buckleyi (Le Roux and Biocca, 1957) (Nematoda: Ancylostomatidae) in the small intestine of Pampas foxes (Lycalopex gymnocercus) (Mammalia: Canidae). This fox is the most abundant native carnivore in southern South America, where it inhabits grasslands, open woodlands and areas highly modified by extensive ranching and agricultural activities. Material from 80 foxes in rural areas of southern Buenos Aires province, Argentina was examined. The intestinal tracts were carefully removed from each carcass and subsequently isolated by ligatures (pylorus and rectum). Examination of the intestinal content was performed using the sedimentation and counting technique. Four foxes (5%) were found to be parasitized with adult specimens of A. buckleyi. This is the first report of Ancylostoma (A.) buckleyi in Argentina and adds L. gymnocercus as new host of this nematode species.

Survey and first molecular characterization of Echinococcus granulosus sensu stricto (G1) in Pampas fox (Lycalopex gymnocercus) in Buenos Aires province, Argentina

Echinococcosis is a zoonosis caused by tapeworms of the genus Echinococcus. Echinococcus granulosus sensu lato (s. l.) has a world-wide distribution and its transmission is primarily maintained in a synanthropic cycle with dogs as definitive hosts and livestock species as intermediate hosts. However, many wild canids also function as definitive hosts for E. granulosus s. l. Echinococcosis in humans is mainly caused by E. granulosus sensu stricto (s. s.) G1 genotype. In the present work, we expanded the epidemiological study on echinococcosis reported cases in Pampas fox (Lycalopex gymnocercus) to provide a prevalence estimate for rural areas of southern Buenos Aires province, Argentina. Ninety-five whole intestines were analyzed using the sedimentation and counting technique with a result of 83 foxes (87.37%) harboring at least one helminth species. E. granulosus s. l. adults were found in one Pampas fox (1.05%). These adult helminthes were E. granulosus s. s. (G1) according to the genotyping analysis of a 450-bp region of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene.

Echinococcus granulosus: Epidemiology and state-of-the-art of diagnostics in animals

Diagnosis and detection of Echinococcus granulosus (sensu lato) infection in animals is a prerequisite for epidemiological studies and surveillance of echinococcosis in endemic, re-emergent or emergent transmission zones. Advances in diagnostic approaches for definitive hosts and livestock, however, have not progressed equally over the last 20 years. Development of laboratory based diagnostics for canids using coproantigen ELISA and also coproPCR, have had a huge impact on epidemiological studies and more recently on surveillance during hydatid control programmes. In contrast, diagnosis of cystic echinococcosis (CE) in livestock still relies largely on conventional post-mortem inspection, despite a relatively low diagnostic sensitivity especially in early infections, as current serodiagnostics do not provide a sufficiently specific and sensitive practical pre-mortem alternative. As a result, testing of dog faecal samples by coproantigen ELISA, often combined with mass ultrasound screening programmes for human CE, has been the preferred approach for monitoring and surveillance in resource-poor endemic areas and during control schemes. In this article we review the current options and approaches for diagnosis of E. granulosus infection in definitive and animal intermediate hosts (including applications in non-domesticated species) and make conclusions and recommendations for further improvements in diagnosis for use in epidemiological studies and surveillance schemes.

Loss of helminth species diversity in the large hairy armadillo Chaetophractus villosus on the Tierra del Fuego Island, Argentina

The aim of this work is to compare the taxonomic diversity of parasite species of the large hairy armadillo Chaetophractus villosus in its native range and in another recently introduced population (Tierra del Fuego island), and to evaluate whether the isolation of the latter determines a decrease in its parasitic diversity. Forty specimens from Buenos Aires and Tierra del Fuego Provinces were collected and examined for helminths. Eleven parasite species were found in the native population, and only one species was present in Tierra del Fuego (Trichohelix tuberculata). This may be explained because isolation and climatic conditions prevent encounters between potential host species and infective forms of parasites. Further sampling will be needed throughout the entire Patagonia steppe to confirm how the characteristic parasitic fauna of C. villosus behaves across the armadillo's southern distribution.

Echinococcosis in wild carnivorous species: epidemiology, genotypic diversity, and implications for veterinary public health

Echinococcosis is a zoonosis caused by helminths of the genus Echinococcus. The infection, one of the 17 neglected tropical diseases listed by the World Health Organization, has a cosmopolitan distribution and can be transmitted through a variety of domestic, synanthropic, and sylvatic cycles. Wildlife has been increasingly regarded as a relevant source of infection to humans, as demonstrated by the fact that a significant proportion of human emerging infectious diseases have a wildlife origin. Based on available epidemiological and molecular evidence, of the nine Echinococcus species currently recognized as valid taxa, E. canadensis G8-G10, E. felidis, E. multilocularis, E. oligarthrus, E. shiquicus, and E. vogeli are primarily transmitted in the wild. E. canadensis G6-G7, E. equinus, E. granulosus s.s., and E. ortleppi are considered to be transmitted mainly through domestic cycles. We summarize here current knowledge on the global epidemiology, geographical distribution and genotype frequency of Echinococcus spp. in wild carnivorous species. Topics addressed include the significance of the wildlife/livestock/human interface, the sympatric occurrence of different Echinococcus species in a given epidemiological scenario, and the role of wildlife as natural reservoir of disease to human and domestic animal populations. We have also discussed the impact that human activity and intervention may cause in the transmission dynamics of echinococcosis, including the human population expansion an encroachment on shrinking natural habitats, the increasing urbanization of wildlife carnivorous species and the related establishment of synanthropic cycles of Echinococcus spp., the land use (e.g. deforestation and agricultural practices), and the unsupervised international trade and translocation of wildlife animals. Following the 'One Health' approach, we have also emphasized that successful veterinary public health interventions in the field of echinococcosis requires an holistic approach to integrate current knowledge on human medicine, veterinary medicine and environmental sciences.