Arthrostoma miyazakiense (Nematoda: Ancylostomatidae) infection in raccoon dogs of Korea and experimental transmission to dogs

Metabarcoding of pathogenic parasites based on copro-DNA analysis of wild animals in South Korea

Four species of dominant wild animals, namely, Prionailurus bengalensis euptilurus, Nyctereutes procyonoides koreensis, Hydropotes inermis argyropus, and Sus scrofa coreanus, are hosts of potential infectious agents, including helminths and protozoa. Therefore, it is necessary to analyze the infectious agents present in these wild animals to monitor and control the spread of pathogens. In the present study, fecal samples from 51 wild animals were collected from the mountains of Yangpyeong, Hoengseong, and Cheongyang in South Korea and metabarcoding of the V9 region of the 18S rRNA gene was performed to identify various parasite species that infect these wild animals. Genes from nematodes, such as Metastrongylus sp., Strongyloides spp., Ancylostoma sp., and Toxocara sp., were detected in the fecal samples from wild animals. In addition, platyhelminthes, including Spirometra sp., Echinostomatidae gen. sp., Alaria sp., Neodiplostomum sp., and Clonorchis sp., and protozoa, including Entamoeba sp., Blastocystis sp., Isospora sp., Tritrichomonas sp., Pentatrichomonas sp., and Cryptosporidium sp., were detected. In the present study, various parasites infecting wild animals were successfully identified using metabarcoding. Our technique may play a crucial role in monitoring parasites within wild animals, especially those causing zoonoses.

Arthrostoma leucurus sp. n. (Nematoda: Ancylostomatidae), A New Hookworm Species Isolated from Asian Badger in China

Purpose

To date, ten validated Arthrostoma species were reported. Here, a new hookworm species was found from Asian badger (Meles leucurus).

Methods

Nineteen hookworms (9 males and 10 females) were collected from the small intestine of two Asian badgers in Xinjiang Uygur Autonomous Region, northwestern China. The hookworms were morphologically examined according to key taxonomic characters, such as anterior extremity direction, structures of oral opening (cutting plates or teeth), vulva location, buccal capsule anatomy (integrated or formed by articulating plates), the length of spicule and gubernaculum, number of plates of buccal capsule, and presence or absence of vulvar papillae.

Results

The hookworm species from Asian badger, here named as Arthrostoma leucurus sp. n., was different from the previously described ten Arthrostoma species. The phylogenetic tree based on the cox1 gene showed that Arthrostoma leucurus sp. n. formed a separate clade, as a sister group to Ancylostoma and Uncinaria species.

Conclusion

Arthrostoma leucurus sp. n., the eleven validated Arthrostoma species, was identified from Asian badger in China.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11686-022-00587-5.

Molecular detection of a novel Ancylostoma sp. by whole mtDNA sequence from pangolin Manis javanica

Background

Ancylostoma species are hematophagous parasites that cause chronic hemorrhage in various animals and humans. Pangolins, also known as scaly anteaters, are mammals that live in soil environments where they are readily exposed to soil-borne parasitic nematodes. However, only a limited number of helminth species have been identified in this animal host so far.

Methods

Ancylostoma sp. was isolated from a wild pangolin, and the complete mitochondrial (mt) genome of Ancylostoma sp. was obtained by Illumina sequencing of total genomic DNA.

Results

The circular complete mt genome that was assembled had a total length of 13,757 bp and comprised 12 protein-coding genes (PCGs), 22 transfer ribosomal RNAs, two ribosomal RNAs (rRNAs), two non-coding regions and one AT-rich region, but lacked the gene coding for ATPase subunit 8 (atp8). The overall AT content of the mt genome of Ancylostoma sp. was 76%, which is similar to that of other nematodes. The PCGs used two start codons (ATT and TTG) and three stop codons (TAA, TAG, and T). The nucleotide identity of the 12 PCGs ranged from 83.1% to 89.7% and had the highest sequence identity with Ancylostoma caninum among species in the Ancylostomatidae family. Also, the pangolin-derived Ancylostoma sp. lacked repeat sequences in the non-coding regions and in the unique sequence of the short non-coding regions, which differentiated it from other Ancylostoma species. In addition, phylogenetic analyses of 18S rRNA and mtDNA sequences revealed that the Ancylostoma sp. was positioned in a separate branch in the subfamily Ancylostomatinae along with other Ancylostoma species.

Conclusions

The Ancylostoma sp. isolated from a pangolin in this study was identified as a possible new Ancylostoma species. The identification of this Ancylostoma sp. from pangolin enriches our knowledge of the species in the Ancylostomatidae family and provides information that will lead to a better understanding of the taxonomy, diagnostics, and biology of hookworms.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05191-0.

Morphological and Molecular Characterization of Toxocara tanuki (Nematoda: Ascaridae) from Korean Raccoon Dog, Nyctereutes procyonoides koreensis

Present study was performed to describe the morphological and molecular characterization of Toxocara tanuki (Nematoda: Ascaridae) from Korean raccoon dog, Nyctereutes procyonoides koreensis, naturally infected in the Republic of Korea (Korea). Juvenile and adult worms of T. tanuki were recovered in 5 out of 10 raccoon dogs examined and the larval worms were detected in 15 out of 20 muscle samples (75%). Small lateral alae were observed on the cranial end of the body in male and female adults and 2 long spicules (3.0–3.5 mm) were characteristically observed in the posterior end of males. In SEM observation, 18 pairs of proximal precloacal, a precloacal median, a postcloacal median and 5 pairs of postcloacal papillae were uniquely revealed in the posterior portion of males, but the proximal papillae were not shown in the lateral ends of females. Molecular analysis on the 18S rRNA partial DNA sequences was revealed the same finding in both samples, adult worms and muscle larvae, which are closely related to T. tanuki. In conclusion, it was confirmed for the first time that T. tanuki is indigenously distributed, the Korean raccoon dog is acted as the natural definitive host of this nematode in Korea and the morphological characteristics of T. tanuki were shown in specific structure for single postcloacal median papilla in male.

The diversity and impact of hookworm infections in wildlife

Hookworms are blood-feeding nematodes that parasitize the alimentary system of mammals. Despite their high pathogenic potential, little is known about their diversity and impact in wildlife populations. We conducted a systematic review of the literature on hookworm infections of wildlife and analyzed 218 studies qualitative and quantitatively. At least 68 hookworm species have been described in 9 orders, 24 families, and 111 species of wild mammals. Black bears, red foxes, and bobcats harbored the highest diversity of hookworm species and Ancylostoma pluridentatum, A. tubaeforme, Uncinaria stenocephala and Necator americanus were the hookworm species with the highest host diversity index. Hookworm infections cause anemia, retarded growth, tissue damage, inflammation and significant mortality in several wildlife species. Anemia has been documented more commonly in canids, felids and otariids, and retarded growth only in otariids. Population- level mortality has been documented through controlled studies only in canines and eared seals although sporadic mortality has been noticed in felines, bears and elephants. The main driver of hookworm pathogenic effects was the hookworm biomass in a population, measured as prevalence, mean burden and hookworm size (length). Many studies recorded significant differences in prevalence and mean intensity among regions related to contrasts in local humidity, temperature, and host population density. These findings, plus the ability of hookworms to perpetuate in different host species, create a dynamic scenario where changes in climate and the domestic animal-human-wildlife interface will potentially affect the dynamics and consequences of hookworm infections in wildlife.

The biological potential of the raccoon dog (Nyctereutes procyonoides, Gray 1834) as an invasive species in Europe-new risks for disease spread?

Invasive wildlife species have the potential to act as additional host and vector species for infectious diseases. The raccoon dog (Nyctereutes procyonides), a carnivore species that has its origin in Asia, was taken as an example to demonstrate biological and ecological prerequisites which enables an invasive species to occupy a new habitat permanently. Studies conducted during the last 20 years identified a total of 35 species of endoparasites, five ectoparasites, six bacterial or protozoan species, and five viruses found in the subspecies Nyctereutes procyonoides ussuriensis in its original and newly occupied habitat or in Nyctereutes procyonoides koreensis in its original habitat, respectively. With reference to raccoon dogs impact as vector species and the relevance for human and animal health, we selected Trichinella spp., Echinococcus multilocularis, Francisella tularensis, rabies virus, and canine distemper virus for detailed description. Results of studies from Finland and Germany furthermore showed that biological characteristics of the raccoon dog make this carnivore an ideal host and vector for a variety of pathogens. This may result in a growing importance of this invasive species concerning the epidemiology of some transmissible diseases in Europe, including the hazard that the existence of autochthonous wildlife, particularly small populations, is endangered. Potential adverse effects on human and animal health in the livestock sector must also be taken into account. Especially with regard to its potential as a reservoir for zoonotic diseases, the raccoon dog should receive more attention in disease prevention and eradication strategies.

Detection of gastrointestinal parasites in raccoon dogs (Nyctereutes procyonoides) in the Seosan reclaimed lands, Korea

This study examined gastrointestinal parasites of raccoon dogs in the Seosan reclaimed lands, Korea. We collected 882 raccoon dog fecal samples and examined them using a fecal flotation technique following standard procedures. Identification was based on the morphology and size of the parasite eggs and oocysts. Nine different helminth eggs and oocysts of Isospora spp. were identified. In total, 314 (35.5%) fecal samples were positive for gastrointestinal helminths or Isospora spp. Double (6%), triple (1%), and quadruple (0.3%) infections were observed. The rates of parasite infection in spring, summer, fall, and winter were 29.8, 20.7, 39.0, and 42.9%, respectively. These results indicate that raccoon dogs host diverse helminths and Isospora spp., posing a potential risk of transmitting parasites to domestic pets and residents in the area. Active epidemiological surveillance with modern molecular techniques and ancillary epidemiological tools is recommended.