Nematodes parasites of the gray fox (Urocyon cinereoargenteus Schreber, 1775) in the seasonally dry tropical highlands of central Mexico

Seek, and you will find: Cryptic diversity of the cardiopulmonary nematode Angiostrongylus vasorum in the Americas

Angiostrongylus vasorum is a metastrongylid parasite infecting wild canids and domestic dogs. Its patchy distribution, high pathogenicity and taxonomical classification makes the evolutionary history of A. vasorum intriguing and important to study. First larval stages of A. vasorum were recovered from feces of two grey foxes, Urocyon cinereoargenteus, from Costa Rica. Sequencing and phylogenetic and haplotypic analyses of the ITS2, 18S and cytochrome oxidase subunit 1 (cox1) fragments were performed. Then p- and Nei´s genetic distance, nucleotide substitution rates and species delimitation analyses were conducted with cox1 data of the specimens collected herein and other Angiostrongylus spp. Cophylogenetic congruence and coevolutionary events of Angiostrongylus spp. and their hosts were evaluated using patristic and phenetic distances and maximum parsimony reconciliations. Specimens from Costa Rica clustered in a separate branch from European and Brazilian A. vasorum sequences in the phylogenetic and haplotype network analyses using the ITS2 and cox1 data. In addition, cox1 p-distance of the sequences derived from Costa Rica were up to 8.6 % different to the ones from Europe and Brazil, a finding mirrored in Nei´s genetic distance PCoA. Species delimitation analysis supported a separate group with the sequences from Costa Rica, suggesting that these worms may represent cryptic variants of A. vasorum, a new undescribed taxon or Angiocaulus raillieti, a synonym species of A. vasorum described in Brazil. Moreover, nucleotide substitution rates in A. vasorum were up to six times higher than in the congener Angiostrongylus cantonensis. This finding and the long time elapsed since the last common ancestor between both species may explain the larger diversity in A. vasorum. Finally, cophylogenetic congruence was observed between Angiostrongylus spp. and their hosts, with cospeciation events occurring at deeper taxonomic branching of host order. Altogether, our data suggest that the diversity of the genus Angiostrongylus is larger than expected, since additional species may be circulating in wild canids from the Americas.

A walk on the wild side: A review of the epidemiology of Toxocara canis and Toxocara cati in wild hosts

Toxocara species are cosmopolitan nematode parasites of companion, domestic and wild hosts. Of the 26 known species of Toxocara, only Toxocara canis and Toxocara cati are definitively zoonotic. The significance of wild carnivores as definitive hosts of T. canis and T. cati respectively, has received far less attention compared to domestic dogs and cats. Complex environmental changes have promoted increasing contact between wildlife, domestic animals and humans that can enhance the risk of pathogen spillover. This review lists a total of 19 species of wild canid host that have been shown to act as definitive hosts for T. canis and a total of 21 species of wild felid host. In general, the number of publications focusing on felid host species is fewer in number, reflecting the general paucity of data on T. cati. The wild canids that have received the most attention in the published literature include the red fox (Vulpes vulpes), the wolf (Canis lupus), and the golden jackal (Canis aureus). The wild felid species that has received the most attention in the published literature is the Eurasian lynx (Lynx lynx). Some non-canid and non-felid hosts also act as definitive hosts of Toxocara species. Certainly, red foxes would appear to be the most significant wild species in terms of their potential to transmit Toxocara to domestic dogs and humans via environmental contamination. This can be explained by their increasing population densities, encroachment into urban areas and their dietary preferences for a wide range of potential paratenic hosts. However, a major challenge remains to assess the relative importance of wild hosts as contributors to environmental contamination with Toxocara ova. Furthermore, one major constraint to our understanding of the significance of wildlife parasitism is a lack of access to samples, particularly from rare host species.

Occurrence of Ancylostoma Caninum from a Gray Fox Urocyon Cinereoargenteus in Southeastern Mexico

The hookworm Ancylostoma caninum is a common nematode of wild and domestic canids worldwide. In Mexico, there are few records of helminths in wild canids, especially in the southeastern region. The aim of the present study was to examine the helminths from a gray fox Urocyon cinereoargenteus in southeastern Mexico. A road-killed female gray fox found in Merida, Yucatan, Mexico, was examined for helminths. Only nematodes were found in the intestine of the gray fox and identified using morphological studies and molecular analysis of 28S rRNA gene fragments. The characteristics exhibited by the nematode specimens were in accordance with descriptions of A. caninum: e. g. oral opening with a pair of prominent chitinous plates bearing three pairs of ventral teeth, lateral rays with a common trunk, dorsal ray divided into two branches with each branch terminating in three digitations. BLAST analysis of the 28S sequence showed similarity and coverage values of 99.8 % and 100 %, respectively, with a sequence of A. caninum from the domestic dog Canis familiaris in Australia. The genetic distance between the Australian specimen and the Yucatan specimen of A. caninum was 0.1 %, that is, they were only different in a single nucleotide. The gray fox examined in this study was found close to a rural community where A. caninum has been recorded from domestic dogs, which could be the source of infection. Our study increases the distribution of this nematode parasitizing the gray fox in Mexico and provides the first nucleotide sequence of A. caninum from the gray fox.

Global prevalence of Strongyloides stercoralis in dogs: A systematic review and meta-analysis

Strongyloides stercoralis is an intestinal parasitic helminth that mainly affects humans and dogs throughout the world. Canine strongyloidosis is generally characterized by asymptomatic infection, with fatal disease in cases of immunodeficiency. This study was conducted in order to evaluate the global prevalence of S. stercoralis in dogs. Six electronic databases were searched for this purpose. The random effects model and 95% confidence intervals (CI) were applied to determine the overall and subgroup pooled prevalence. Heterogeneity was assessed by Cochran's Q test and I2 statistic. In total, 56 datasets from 50 studies from 1,202 peer-reviewed papers were included in the current meta-analysis. 20,627 dogs were assessed in 27 countries across six World Health Organization (WHO) regions. The global prevalence of S. stercoralis infection among dogs was 6% (95% CI 4–8%; 868/20,627). According to WHO regions, the estimated prevalence ranges 2% to 11% as follows: Western Pacific (11%, 0–31%); Africa (9%, 2–19%); America (6%, 3–11%); South-East Asia (5%, 1–13%)’ Europe (3%, 2–5%); and Eastern Mediterranean (2%, 0–6%). The pooled prevalence of S. stercoralis infection in dog owners was 7% (1–18%). The prevalence of S. stercoralis infection in studies based on serological assays was significantly higher than other techniques (29%, 20–39%). Younger female dogs, less than one year old, from rural areas had higher prevalence rates than their male counterparts, with no statistically significant differences. From this review, it is concluded that the low global prevalence of S. stercoralis in dogs may be strongly associated with low sensitivity diagnostic methods applied in most studies leading to the underestimation of infection rates. Therefore, the improvement of diagnostic techniques is recommended for precise evaluation of the disease.

Dog care and parasitosis in a rural community of Patagonia: An integrative approach

Human interaction with dogs can potentially lead to zoonoses. The aim of this integrative approach is to describe the relationship between dog parasites, dog care, and the human population of a rural Patagonian village. Surveys were carried out to evaluate owners' attitudes towards dogs, and coproparasitological and coproELISA analyses were performed to determine parasitic infection values. Fur samples and vegetable garden soil were also analyzed. A multivariate regression was performed to identify factors determining infection. All households owned at least one dog, of which only 54.9% had been dewormed in the past three months, and almost half of which were allowed to roam freely. Dogs with protozoan and helminth infections represented 68.8% of the total, 50% being parasitized by helminths of 7 species, including the zoonotic Toxocara canis, Uncinaria sp. Ancylostoma sp. and Echinococcus sp. All hair samples were negative, but 42.8% of vegetable gardens harbored Ancylostomatidae larvae. Statistical analyses indicated that the predictor "time since last deworming" explained infections by Cryptosporidium sp. and helminths, while the predictors "number of dogs per household", "sex", and "freedom to roam" explained the infections by helminths. This shows that the longer the time interval since the last deworming treatment, the greater the probability of a dog being infected by some type of parasite, either Cryptosporidium sp. or a helminth. On the other hand, the probability of being infected by helminths increased when there was more than one dog in the household. Furthermore, male dogs and dogs allowed to roam freely were more likely to be infected. Considering the inadequate care and sanitary status of dogs infected with zoonotic species, it is necessary to raise awareness of the need for responsible care of dogs.

Dioctophimosis: A Parasitic Zoonosis of Public Health Importance

Dioctophyme renale, the giant kidney worm, is a renal nematode from domestic and wild mammals that has zoonotic potential. In humans, dioctophimosis has been reported in several countries, mainly on the Asian continent, totaling more than 40 cases, which describe the parasite mainly infecting the kidneys, bladder, urethra and skin. Infection in animals and humans is related to the ingestion of the infective larva (L3) present in the aquatic oligochaete annelid (mandatory intermediate host) or fish and anurans (facultative paratenic hosts). Thus, the infection is related to the habit of drinking water contaminated with the mandatory intermediate host, as well as raw or undercooked meat from the facultative paratenic hosts. Dioctophimosis destroys the renal parenchyma and, in some cases, can cause the death of its hosts. In this chapter, we discuss the main topics regarding dioctophimosis in humans, domestic and wild animals, highlighting its importance in public health.

Dioctophyme renale (Goeze, 1782) (Nematoda, Dioctophymidae) parasitic in mammals other than humans: A comprehensive review

A comprehensive review of the infection of mammals with the nematode Dioctophyme renale (Goeze, 1782) (Nematoda, Dioctophymidae) is presented. Mammals, including man, are the definitive hosts for this parasite. Several aspects of the infection with the parasite in mammals other than humans are critically evaluated: geographical distribution, host species recorded so far and the relative importance of the different hosts, location of parasites within the host, prevalence and intensity of the infection, diagnostic methods, pathology induced by the parasites, epidemiology and the methods of control and treatment. The authors provide an updated review about the infection, based on a extensive bibliographic search worldwide, and point out the most relevant aspects of the biology of the parasite as well as several research topics which need to be explored for a better understanding of the biology of this interesting and important parasitic nematode.

Zoonotic nematodes of wild carnivores

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.

A Review of Strongyloides spp. Environmental Sources Worldwide

Strongyloides spp. are parasitic nematodes that are transmitted through the environment and are capable of causing disease. These nematodes affect an estimated 3–300 million humans worldwide. Identifying the environmental reservoirs of Strongyloides spp. is essential for the development of appropriate control strategies. This systematic literature review examined all published studies that identified Strongyloidesstercoralis, Strongyloidesfuelleborni, Strongyloidesfuellebornikellyi, and Strongyloides spp. from an environmental source. Most studies detected the nematode from dog and primate fecal samples. Other environmental sources identified were ruminants, cats, rodents, insects, water, soil, as well as fruit and vegetables. Most studies used microscopy-based identification techniques; however, several employed molecular-based techniques, which have become increasingly popular for the detection of Strongyloides spp. A limitation identified was a lack of studies that comprehensively screened all potential environmental samples in a region. Future research should undertake this holistic screening process to identify which environmental reservoirs pose the greatest significance to human health. Potential controls can be identified through the identification of environmental sources. Understanding where Strongyloides spp. is commonly found within the environment of endemic areas will inform environmental control strategies to reduce this neglected disease.

Ectopic infection by Dioctophyme renale in a dog from Georgia, USA, and a review of cases of ectopic dioctophymosis in companion animals in the Americas

We report a case of ectopic dioctophymosis in an outdoor, eight-year-old spayed female, Coonhound-mix dog from Murrayville, Hall County, Georgia, USA. The dog presented to the clinic with an apparent puncture wound on her right, most caudal mammary gland, draining a serosanguinous discharge along with significant edema and thickening of the surrounding tissues. After initial physical examination the dog was placed into a cage awaiting diagnostic procedures. A couple of hours later, a bright red, live nematode was found in the bottom of the cage and submitted to the Parasitology Diagnostic Laboratory, Department of Infectious Diseases of the University of Georgia College of Veterinary Medicine. The specimen was morphologically identified as a female Dioctophyme renale, measuring 30 cm in length. The wound was cleaned with chlorhexidine solution. The patient was started on cefpodoxime 100 mg orally, once daily for 10 days. The dog had recent history of a mammary tumor on the left chain. After a week, an ultrasound examination confirmed integrity of the kidneys. Herein, we also provide a review on cases of ectopic dioctophymosis in companion animals in the Americas. Such cases are not uncommon, and nematodes may be found in various organs and tissues including the abdominal and thoracic cavities, scrotum, uterus, and mammary glands.

Gray fox (Urocyon cinereoargenteus) parasite diversity in central Mexico

Mexico has a long history of parasitological studies in communities of vertebrates. However, the mega diversity of the country makes fauna inventories an ongoing priority. Presently, there is little published on the parasite fauna of gray foxes (Urocyon cinereoargenteus Schereber, 1775) and this study provides new records of parasites for gray foxes in central Mexico. It is a continuation of a series of previous parasitological studies conducted with this carnivore in Mexico from 2003 to the present. A total of 24 foxes in the Parque Nacional El Cimatario (PANEC) were trapped, anaesthetized, and parasites recovered. The species found were Dirofilaria immitis, Ctenocephalides canis, C. felis, Euhoplopsillus glacialis affinis (first report for gray foxes in Mexico) Pulex simulants, and Ixodes sp. Three additional gray fox carcasses were necropsied and the parasites collected were adult nematodes Physaloptera praeputialis and Toxocara canis. The intensive study of the gray fox population selected for the 2013-2015 recent period allowed for a two-fold increase in the number of parasite species recorded for this carnivore since 2003 (nine to 18 parasite species), mainly recording parasitic arthropods, Dirofilaria immitis filariae and adult nematodes. The parasite species recorded are generalists that can survive in anthropic environments; which is characteristic of the present ecological scenario in central Mexico. The close proximity of the PANEC to the city of Santiago de Queretaro suggests possible parasite transmission between the foxes and domestic and feral dogs. Furthermore, packs of feral dogs in the PANEC might have altered habitat use by foxes, with possible impacts on transmission.