Multiplex PCR identification of Taenia spp. in rodents and carnivores

Investigation and genetic polymorphism analysis of rodents infected with Echinococcus in Ili Prefecture, Xinjiang Uygur Autonomous Region, China

Introduction

Alveolar echinococcosis (AE) is a life-threatening disease in humans caused by the larval stage of Echinococcus multilocularis. Domestic animals, dogs, foxes, and small mammals constitute the circular chain of AE. To evaluate the infection, distribution, and genetic polymorphism of AE in the Ili Prefecture (Nilka, Xinyuan and Zhaosu), we conducted this survey.

Methods

In June and July 2018, 267 small mammals were captured using water-infusion and mousetrap methods. Combined pathogenic and molecular biological methods were used to observe the histopathology of Echinococcus carried by rodents, amplify the mitochondrial nad1 gene of the pathogen, and investigate the genotype and haplotype diversity of Echinococcus in rodents in Ili Prefecture.

Results

Morphological identification revealed that these captured small mammals belonged to three species, with Microtus gregalis being the dominant species (183/267). Pathological and molecular biological results confirmed that E. multilocularis was the pathogen of echinococcosis in small mammals, with an infection rate of 15.73% (42/267). Among the three areas sampled, the highest infection rate of rodents was 25.45% (14/55) in Nilka County. However, there was no significant difference in the infection rates between regions (χ2 = 5.119, p > 0.05). Of the three captured rodent species, M. gregalis had the highest infection rate of 17.49% (32/183), but there was no significant difference in infection rates between the rodent species (χ2 = 1.364, p > 0.05). Phylogenetic analyses showed that the nad1 gene sequences obtained in this study clustered in the same clade as isolates from China. These isolates contained 21 haplotypes (Hap_1-21); Hap_2 was the most common haplotype (9/42). Furthermore, haplotype diversity (0.925 ± 0.027) and nucleotide diversity (0.01139 ± 0.00119) were higher in the Ili Prefecture than in other regions, indicating that population differentiation was high. Tajima's D and Fu's Fs tests were negative (p > 0.10), indicating that the population had expanded. The low fixation index (Fst) ranged from 0.00000 to 0.16945, indicating that the degree of genetic differentiation was different among different populations.

Discussion

In summary, Ili Prefecture is a high incidence area of AE, and Microtus spp. may play an important role in the transmission of AE in this area. The results of this study provide basic data for further study of the molecular epidemiology, genetic differences, and control of E. multilocularis in the Ili Prefecture, Xinjiang.

Comprehensive Diagnosis, Treatment, and Outcome of Taenia crassiceps Cysticercosis in a Ring-Tailed Lemur (Lemur catta) from a Croatian Zoo: No Longer Unusual?

Taenia crassiceps is a zoonotic tapeworm of the genus Taenia that is distributed throughout the Northern Hemisphere. Wild and domestic carnivores are final hosts, while rodents and rabbits are primarily intermediate hosts, although many other mammals may harbour the larval stage, Cysticercus longicollis. This case report aims to describe C. longicollis infection in a lemur and molecularly characterise the isolated parasite. The excised lesion was subjected to morphological and histopathological examination, which revealed cysticerci of the tapeworm. Formalin-fixed and paraffin-embedded block (FFPEB), as well as the cysticerci fixed with formalin stored for one year, were subjected to molecular analysis, which aimed at detecting the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of Taenia sp. Based on the morphological characteristics, the parasite was identified as a metacestode of T. crassiceps. The presence of the cox1 gene was detected using polymerase chain reaction (PCR) in all samples. A randomly selected PCR product was sequenced and compared with other sequences from the GenBank database, confirming that the detected parasite was T. crassiceps. This article reports the first case of T. crassiceps cysticercosis in a lemur (Lemur catta) in Croatia and emphasises the potential risk of transmission from wild carnivores.

Identification and phylogenetic analysis of Taenia spp. parasites found in wildlife in the Emilia-Romagna region, northern Italy (2017-2022)

The recent expansion of the habitat of several wildlife species, comprising anthropized areas, is a relevant risk factor for many zoonotic diseases and should be considered in national and regional sanitary monitoring systems. We evaluated adult intestinal Taenia spp. parasites isolated from wild carnivores and cystic larval forms isolated from wild mammals analysed at the Istituto Zooprofilattico Sperimentale della Lombardia ed Emilia-Romagna (IZSLER) as part of the regional wildlife sanitary surveillance plan. Then, we assessed parasite species through molecular analysis (multiplex PCR followed by ribosomal 12S subunit gene sequencing) in order to update the epidemiological situation on Taeniids infection in the Emilia-Romagna wildlife, reporting the prevalence of each isolated species. The most commonly isolated species was Taenia serialis, which we detected in both wolves and foxes as definitive hosts and in roe deer as intermediate host. More attention on the distribution of Taeniids in wildlife should be paid, considering their potential zoonotic role: several Taenia spp. (Taenia solium, Taenia multiceps, Taenia serialis, Taenia brauni, Taenia glomerulatus) are known for causing coenurosis in humans, with possible severe or fatal outcomes.

Host and geographic differences in prevalence and diversity of gastrointestinal helminths of foxes (Vulpes vulpes), coyotes (Canis latrans) and wolves (Canis lupus) in Québec, Canada

Wild canids are hosts to a wide range of parasites and can play a role in transmission of zoonoses. As many parasites are transmitted through food webs, and wild canids are at high trophic levels, parasite prevalence and diversity in wild canids can serve as excellent indicators of ecosystem health. Our main objectives were to update knowledge on the composition of gastrointestinal helminths in wild canids from Québec, Canada, and to describe differences in parasite prevalence and diversity among canid species and regions. Hunters and trappers provided whole carcasses of red foxes (Vulpes vulpes) (N = 176), and intestinal tracts of coyotes (Canis latrans) (N = 77) and gray wolves (Canis lupus) (N = 23) harvested for non-research purposes over the winter of 2016-2017. A modified Stoll's centrifugation sucrose flotation on feces of 250 wild canids was used, and eggs of one family and eight genera of parasitic helminths were recovered: diphyllobothriids, Taenia/Echinococcus spp., Capillaria spp., Toxascaris sp., Toxocara sp., Trichuris sp., Uncinaria sp., and Metorchis sp. Adult Taenia spp. cestodes were recovered from 61 of 276 (22%) canids. Six different species (T. hydatigena, T. twitchelli, T. crassiceps, T. polyacantha, T. krabbei, and T. pisiformis-"like") were differentiated based on DNA sequenced from 65 individual adult cestodes using primers for the nicotinamide adenosine dinucleotide dehydrogenase subunit 1 (ND1) and cytochrome c oxidase subunit 1 (CO1) mitochondrial DNA loci. Alaria sp. trematodes infected 89 of 276 canids (32%). A subset were identified as A. americana at the CO1 locus. The marine trematode Cryptocotyle lingua was reported for the first time in foxes in the province of Québec. These results help us understand more fully the predator-prey relationships within this group of canids. This baseline data in regional parasite prevalence and intensity is critical in order to detect future changes following ecological disturbances due to climate and landscape alterations.

Gastrointestinal helminths of gray wolves (Canis lupus lupus) from Sweden

As the Scandinavian wolf population is limited in size, it is only rarely subject to systematic studies on its disease biology, especially gastrointestinal parasites. Therefore, this study aims to describe the prevalence of gastrointestinal helminths of gray wolves hunted on a limited license as a part of a wildlife management program. Helminths of 20 wolves were examined post mortem by macroscopy and coprology. Intestinal worms of five species were recovered from 18 wolves (90%): Uncinaria stenocephala (90%), Taenia spp. (45%), Alaria alata (25%), and Mesocestoides spp. (5%). Of the taeniid specimens typed by multiplex PCR and sequencing of the cox1 gene, 25% belonged to Taenia hydatigena and 25% to Taenia krabbei. The overall species diversity was low compared to findings from wolves of the northern hemisphere. Fecal eggs of Eucoleus boehmi were detected in 12 wolves (60%). Fecal metastrongylid larvae were found in seven individuals (39%), but PCR analyses specific for Angiostrongylus vasorum were negative. The wolves were in good body condition suggesting that the parasite infestation had no negative impact on the general health of the examined wolves. Although some of the recovered parasite species have zoonotic or veterinary impact, it is not likely that the spare wolf population pose substantial threat to human or veterinary health.

A conventional PCR for differentiating common taeniid species of dogs based on in silico microsatellite analysis

Canine taeniids are among the major tapeworms with remarkable medical and economic significance. Reliable diagnosis and differentiation of dog taeniids using simple and sensitive tools are of paramount importance for establishing an efficient surveillance system. Microsatellites as abundant unique tandem repeats of short DNA motifs are useful genetic markers for molecular epidemiological studies. The purpose of the present study was to find a primer pair for rapid differentiation of major tapeworms of dogs, Taenia hydatigena, T. multiceps, T. ovis and Echinococcus granulosus, by screening existing nucleotide data. All the mitochondrial genome records as well as non-coding ITS1 sequences of Taeniidae species were downloaded from Nucleotide database from NCBI. For prediction and analysis of potential loci of STR/SSR in ITS1 as well as mitochondrial regions, we used ChloroMitoSSRDB 2.0 and GMATo v1.2. software. Different tapeworm species were categorized according to different motif sequences and type and size of each microsatellite locus. Three primer sets were designed and tested for differentiating taeniid species and evaluated in a conventional PCR system. Four taeniid species were successfully differentiated using a primer pair in a simple conventional PCR system. We predicted 2-19 and 1-4 microsatellite loci in ITS1 and mitochondrial genome, respectively. In ITS1, 41 Di and 21 Tri motifs were found in the taeniids while the majority of the motifs in the mitochondrial genome were Tetra (89) and Tri (70). It is documented that the number and diversity of microsatellite loci is higher in nuclear ITS1 region than mostly coding mitochondrial genome.

Molecular detection of Taenia spp. in dogs' feces in Zanjan Province, Northwest of Iran

AIM

Echinococcus and Taenia spp. are important but neglected zoonotic helminths of dogs. Dogs as the most relevant definitive hosts harbor several species of Taenia and Echinococcus simultaneously in their gastrointestinal lumen which are morphologically indistinguishable. In this study, we used a multiplex polymerase chain reaction (PCR) method to identify Taeniid infections which seem to be highly distributed in the study region.

MATERIALS AND METHODS

A total of 450 dog fecal samples were collected from eight different areas of Zanjan province, northwest of Iran, and examined using a flotation method followed by multiplex PCR for detection and identification of parasites' eggs.

RESULTS

Gastrointestinal parasites were found in 86 out of 450 fecal samples (19.1%) by microscopic examination. Taeniid eggs were observed in 5.6% of samples, containing 0.45%, 3.8%, and 1.3% Echinococcus granulosus, Taenia spp., and mix infection of both E. granulosus and Taenia spp., respectively. Echinococcus multilocularis was absent in the samples.

CONCLUSION

A relatively low rate of E. granulosus (1.8%) was observed in this study. However, risks of this parasite should not be overlooked, and control programs need to be extended for this species and other Taeniid spp. In particular, dogs are recommended to be dewormed more frequently.

Endoparasitic fauna of red foxes (Vulpes vulpes) and golden jackals (Canis aureus) in Serbia

Wild canides have a high epizootiological - epidemiological significance, considering that they are hosts for some parasites which spread vector born diseases. Increased frequency of certain interactions between domestic and wild canides increases the risk of occurrence, spreading and maintaining the infection of parasitic etiology in domestic canides. The research was conducted in 232 wild canides (172 red foxes and 60 golden jackals). The examined material was sampled from foxes and jackals, which were hunted down between 2010 and 2014, from 8 epizootiological areas of Serbia (North-Bačka, West-Bačka, Southern-Banat, Moravički, Zlatiborski, Raški, Rasinski and Zaječarski district). On completing the parasitological dissection and the coprological diagnostics, in wild canides protozoa from the genus Isospora were identified, 3 species of trematoda (Alaria alata, Pseudamphistomum truncatum and Metagonimus yokogawai), cestods from the genus Taenia and 5 species of nematodes (Toxocara canis, Ancylostomatidae, Trichuris vulpis and Capillaria aerophila). The finding of M. yokogawai in golden jackals were, to the best of our knowledge, one of the first diagnosed cases of metagonimosis in golden jackals in Serbia. The continued monitoring of the parasitic fauna of wild canides is needed to establish the widespread of the zoonoses in different regions of Serbia, because they present the reservoirs and/or sources of these infections.

[Subcutaneous Taenia crassiceps-cysticercosis in a dog with Cushing's syndrome]

A male, 12-year-old Cairn terrier suffering from Cushing's syndrome with two therapy-resistant inflammatory subcutaneous lesions was examined pathomorphologically and parasitologically. Within the subcutaneous tissue, there was a suppurative to necrotizing and histiocytic inflammation present with the formation of caverns. Intralesional whitish-grey cysts with a diameter of 1-4 mm were detected. Molecular investigations of the cysts confirmed the preliminary morphological identification as Cysticercus longicollis. The adenohypophysis showed an infiltrative growing carcinoma. Cysticercus longicollis is the metacestode of Taenia (T.) crassiceps, a tapeworm of foxes and coyotes. Small rodents are typical intermediate hosts, in which the metacestode develops within the body cavities as well as in the subcutis. Subcutaneous cysticercosis after infection with eggs of T. crassiceps is also described in different domestic animal species and in humans, who represent aberrant intermediate hosts. Immunosuppression due to Cushing's syndrome, probably caused by the tumor of the adenohypophysis, may have played a role in the pathogenesis of the present case.

Mitochondrial DNA diversity in the acanthocephalan Prosthenorchis elegans in Colombia based on cytochrome c oxidase I (COI) gene sequence

Prosthenorchis elegans is a member of the Phylum Acanthocephala and is an important parasite affecting New World Primates in the wild in South America and in captivity around the world. It is of significant management concern due to its pathogenicity and mode of transmission through intermediate hosts. Current diagnosis of P. elegans is based on the detection of eggs by coprological examination. However, this technique lacks both specificity and sensitivity, since eggs of most members of the genus are morphologically indistinguishable and shed intermittently, making differential diagnosis difficult, and coprological examinations are often negative in animals severely infected at death. We examined sequence variation in 633 bp of mitochondrial DNA (mtDNA) cytochrome c oxidase I (COI) sequence in 37 isolates of P. elegans from New World monkeys (Saguinus leucopus and Cebus albifrons) in Colombia held in rescue centers and from the wild. Intraspecific divergence ranged from 0.0 to 1.6% and was comparable with corresponding values within other species of acanthocephalans. Furthermore, comparisons of patterns of sequence divergence within the Acanthocephala suggest that Prosthenorchis represents a separate genus within the Oligacanthorhynchida. Six distinct haplotypes were identified within P. elegans which grouped into one of two well-supported mtDNA haplogroups. No association between haplogroup/haplotype, holding facility and species was found. This information will help pave the way to the development of molecular-based diagnostic tools for the detection of P. elegans as well as furthering research into the life cycle, intermediate hosts and epidemiological aspects of the species.

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First report of mitochondrial DNA sequence in Prosthenorchis sp.

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Surprising genetic diversity in Prosthenorchis elegans.

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Six different haplotypes detected within Prosthenorchis elegans which grouped into one of two well-supported mtDNA lineages.

Novel PCRs for differential diagnosis of cestodes

Cestodes or tapeworms belong to a diverse group of helminths. The adult Taenia saginata and Taenia solium tapeworm can infest the human gut and the larval stage of Echinococcus spp. and T. solium can infect tissues of the human body, causing serious disease. Molecular diagnostics can be performed on proglottids, eggs and on cyst fluids taken by biopsy. Detection of cestodes when a helminthic infection is suspected is of vital importance and species determination is required for appropriate patient care. For routine diagnostics a single test that is able to detect and type a range of cestodes is preferable. We sought to improve our diagnostic procedure that used to rely on PCR and subsequent sequencing of the Cox1 and Nad1 genes. We have compared these PCRs with novel PCRs on the 12S rRNA and Nad5 gene and established the sensitivity and specificity. A single PCR on the 12S gene proved to be very suitable for detection and specification of Taenia sp. and Echinococcus sp. Both targets harbour enough polymorphic sites to determine the various Echinococcus species. The 12S PCR was most sensitive of all tested.

Progress on research on rodents and rodent-borne zoonoses in South-east Asia

This review aims to synthesise knowledge regarding the taxonomy of South-east Asian murine rodents and the challenges associated with the identification of habitat preferences and associated rodent-borne diseases. Recent studies concerning the Rattini tribe have identified unclear species boundaries that would benefit from further investigation. The development of barcoding may allow more accurate identification of rodents, specifically for complex species. However, knowledge on the distribution and habitat specialisations of many common murine rodents is still scarce, particularly regarding the specific habitat preferences of most synanthropic rodent species (Rattus tanezumi or Rattus exulans). Several studies have analysed the prevalence of major rodent-borne diseases in South-east Asia and it appears that the greatest risk of rodent zoonoses are in the lowland rain-fed and irrigated landscapes, generally in and around rice fields.

Loop-mediated isothermal amplification (LAMP) assay for the identification of Echinococcus multilocularis infections in canine definitive hosts

Background

Alveolar echinococcosis, caused by the metacestode larval stage of Echinococcus multilocularis, is a zoonosis of public health significance and is highly prevalent in northwest China. To effectively monitor its transmission, we developed a new rapid and cheap diagnostic assay, based on loop-mediated isothermal amplification (LAMP), to identify canine definitive hosts infected with E. multilocularis.

Methods

The primers used in the LAMP assay were based on the mitochondrial nad5 gene of E. multilocularis and were designed using Primer Explorer V4 software. The developed LAMP assay was compared with a conventional PCR assay, using DNA extracted from the feces of dogs experimentally infected with E. multilocularis, on 189 dog fecal samples collected from three E. multilocularis-endemic regions in Qinghai province, the People’s Republic of China, and 30 negative control copro-samples from dogs from an area in Gansu province that had been subjected to an intensive de-worming program. Light microscopy was also used to examine the experimentally obtained and field collected dog copro-samples for the presence of E. multilocularis eggs.

Results

The E. multilocularis-positivity rates obtained for the field-collected fecal samples were 16.4% and 5.3% by the LAMP and PCR assays, respectively, and all samples obtained from the control dogs were negative. The LAMP assay was able to detect E. multilocularis DNA in the feces of experimentally infected dogs at 12 days post-infection, whereas the PCR assay was positive on the 17th day and eggs were first detectable by light microscopy at day 44 post-challenge.

Conclusion

The earlier specific detection of an E. multilocularis infection in dog copro-samples indicates that the LAMP assay we developed is a realistic alternative method for the field surveillance of canines in echinococcosis-endemic areas.

Morphological and molecular analyses of larval taeniid species in small mammals from contrasting habitats in Denmark

Taeniid infections in intermediate hosts manifest themselves as extraintestinal larval stages which, in early development, lack species-specific characteristics. The inability to distinguish infections of zoonotic importance such as Echinococcus multilocularis from other taeniid infections that have mainly veterinary significance stimulated the development of species-specific molecular diagnostics. In this study, the prevalence of taeniid infections in potential intermediate hosts was evaluated using both morphological diagnosis and a newly described multiplex polymerase chain reaction (PCR) for species determination. Small mammals (N= 719) were trapped in three different types of habitats in north-east Zealand, Denmark. The sensitivity of the multiplex PCR (90.5%) exceeded that of morphological examination (57.9%) for identifying 95 taeniid infections. The use of the multiplex PCR resulted in higher prevalence rates due to improved detection of immature liver infections with Hydatigera taeniaeformis and Versteria mustelae, but did not affect the observed prevalence rates of peritoneal metacestodes of Taenia polyacantha. The prevalence of taeniid infections showed a significant difference according to habitat type, potentially identifying a 'sylvatic' transmission and an 'urban' transmission, with marked variation among different taeniid species. Versteria mustelae and T. polyacantha were more prevalent in rural forests, while infections with H. taeniaeformis were dominant in urban parks/forests and in residential and farm gardens. The multiplex PCR facilitated a better utilization of wildlife samples by yielding a higher number of definitive diagnoses of ambiguous taeniid infections in liver lesions, allowing for more accurate epidemiological data and, hence, a more accurate risk assessment.

Molecular identification of Echinococcus multilocularis infection in small mammals from Northeast, Iran

BACKGROUND

Alveolar echinococcosis is a zoonotic disease caused by the metacestode of Echinococcus multilocularis. Many species of small mammals, including arvicolid rodents or Ochotona spp., are natural intermediate hosts of the cestode. The main aim of this study was to identify natural intermediate hosts of E. multilocularis in Chenaran County, Razavi Khorasan Province, northeastern Iran, where the prevalence of infected wild and domestic carnivores is high.

METHODOLOGY/PRINCIPAL FINDINGS

A program of trapping was carried out in five villages in which this cestode was reported in carnivores. The livers of 85 small mammals were investigated for the presence of E. multilocularis infection using multiplex PCR of mitochondrial genes. Infections were identified in 30 specimens: 23 Microtus transcaspicus, three Ochotona rufescens, two Mus musculus, one Crocidura gmelini, and one Apodemus witherbyi.

CONCLUSIONS/SIGNIFICANCE

A range of small mammals therefore act as natural intermediate hosts for the transmission of E. multilocularis in Chenaran County, and the prevalence suggested that E. multilocularis infection is endemic in this region. The existence of the life cycle of this potentially lethal cestode in the vicinity of human habitats provides a significant risk of human infection.

Molecular identification of Taenia spp. in the Eurasian lynx (Lynx lynx) from Finland

Cestodes of the genus Taenia are parasites of mammals, with mainly carnivores as definitive and herbivores as intermediate hosts. Various medium-sized cats, Lynx spp., are involved in the life cycles of several species of Taenia. The aim of the present study was to identify Taenia tapeworms in the Eurasian lynx (Lynx lynx) from Finland. In total, 135 tapeworms from 72 lynx were subjected to molecular identification based on sequences of 2 mtDNA regions, the cytochrome c oxidase subunit 1 and the NADH dehydrogenase subunit 1 genes. Available morphological characters of the rostellar hooks and strobila were compared. Two species of Taenia were found: T. laticollis (127 samples) and an unknown Taenia sp. (5 samples). The latter could not be identified to species based on mtDNA, and the rostellar hooks were short relative to those described among other Taenia spp. recorded in felids from the Holarctic region. In the phylogenetic analyses of mtDNA sequences, T. laticollis was placed as a sister species of T. macrocystis, and the unknown Taenia sp. was closely related to T. hydatigena and T. regis. Our analyses suggest that these distinct taeniid tapeworms represent a putative new species of Taenia. The only currently recognized definitive host is L. lynx and the intermediate host is unknown.

Molecular identification of Mesocestoides spp. from intermediate hosts (rodents) in central Europe (Poland)

Genus Mesocestoides is a representative of the small cyclophyllidean family Mesocestoididae that is found parasitizing the small intestine of carnivores. The life cycle of cestodes from this genus is complex and requires two intermediate hosts. Cysticercoids are produced in the first intermediate host (oribatid mites), which when eaten by the second intermediate host (mainly rodents, but also other mammalian species, birds, reptiles, or amphibians) form tetrathyridia in the body cavity. Because of the rich history of nomenclatural evaluation of Mesocestoididae, the taxonomic status within the genus Mesocestoides is still unclear. Additional problem constitute the difficulty or even the impossibility in the determination of tetrathyridia based on morphological features. Thus, the aim of our study was to identify a molecular characteristic of the isolates of Mesocestoides from the second intermediate hosts (rodents) based on nuclear and mitochondrial ribosomal DNA data. We choose to analyze metacestodes isolated from two species of rodents (Apodemus agrarius and Myodes glarolus) from different sites. As a result of amplification of 18S rDNA, we obtained partial sequences from four isolates ranging from 1,116 to 1,162 bp. In relation to mitochondrial sequence, 354 bp product of 12S rDNA was obtained from one isolate. The neighbor joining and maximum parsimony trees were constructed in order to examine the phylogenetic relationship within Mesocestoides spp. occurring in rodents from central Europe. The results of our research on the larval stages from rodents, living in a periphery of urban agglomeration as well as in an area of reserve protection, confirm the data of more frequently occurring Mesocestoides litteratus.