Intraspecific variation between the ITS sequences of Toxocara canis, Toxocara cati and Toxascaris leonina from different host species in south-western Poland

Microscopic and molecular prevalence and associated risk factors with Toxocara and Blastocystis infection in dogs and cats in Mitidja, Algeria

Domestic dogs and cats can serve as a source of environmental contamination with Toxocara spp. and Blastocystis spp., and this represents a neglected public and veterinary health problem. We assessed the microscopic and molecular prevalence of these species in a locality in Algeria and identified the associated risk factors. The faeces of 225 dogs and 78 cats were collected in Mitidja between March and July 2022. The samples were analysed by coproscopy and by polymerase chain reaction (PCR) targeting the Internal Transcribed Spacer 2 (ITS2) and Small Subunit Ribosomal (SSU-RNA) of T. canis and Blastocystis spp. respectively. The overall microscopic prevalence of Toxocara spp. in dogs and cats was 9.78 ± 1.98% and 12.82 ± 7.42%, respectively. The rate of Blastocystis spp. was 15.11 ± 2.39% and 15.38 ± 4.08% in dogs and cats, respectively while the molecular prevalence of T. canis in dogs was 4.89 ± 1.44% and in cats 1.28 ± 1.27%; the prevalence of Blastocystis spp. was 41.78 ± 3.29% and 34.62 ± 5.39% in dogs and cats, respectively. Phylogenetic and phylogeographic analyses identified the presence of the H1 subtype of T. canis in dogs, and the ST1 subtype of Blastocystis in dogs and cats. Dogs with clinical signs were more likely to be infected with T. canis (OR 6.039, P < 0.05) than healthy dogs. This study demonstrates that dogs and cats are carriers of Toxocara spp. and Blastocystis spp. and are therefore a source of environmental contamination. Veterinarians and human health professionals should work together to implement control strategies as part of a "One Health" approach to improving animal health and reducing the risk of transmission to humans.

Prevalence of Gastrointestinal Parasites in Zoo Animals and Phylogenetic Characterization of Toxascaris leonina (Linstow, 1902) and Baylisascaris transfuga (Rudolphi, 1819) in Jiangsu Province, Eastern China

The burden of gastrointestinal parasites in zoo animals has serious implications for their welfare and the health of veterinarians and visitors. Zhuyuwan Zoo is located in the eastern suburb of Yangzhou city in eastern China, in which over 40 species of zoo animals are kept. In order to understand the infection status of GI parasites in Zhuyuwan Zoo, a total of 104 fresh fecal samples collected randomly from birds (n = 19), primates (n = 19), and non-primate mammals (n = 66) were analyzed using the saturated saline flotation technique and nylon sifter elutriation and sieving method for eggs/oocysts, respectively. Two Ascaris species were molecularly characterized. The results showed that the overall prevalence of parasitic infection was 42.3% (44/104). The parasitic infection rate in birds, primates, and non-primate mammals were 26.3% (5/19), 31.6% (6/19), and 50.0% (33/66), respectively. A total of 11 species of parasites were identified, namely, Trichostrongylidae, Capillaria sp., Trichuris spp., Strongyloides spp., Amidostomum sp., Toxascaris leonina, Baylisascaris transfuga, Parascaris equorum, Paramphistomum spp., Fasciola spp., and Eimeria spp. Paramphistomum spp. eggs were first detected from the captive Père David's deer, and Fasciola spp. eggs were first reported from sika deer in zoo in China. A sequence analysis of ITS-2 and cox1 showed that the eggs isolated from the African lion (Panthera leo Linnaeus, 1758) were T. leonina, and the eggs from the brown bear (Ursus arctos Linnaeus, 1758) were B. transfuga. The public health threat posed by these potential zoonotic parasitic agents requires attention. These results lay a theoretical foundation for prevention and control of wild animal parasitic diseases at zoos in China.

Molecular Characterization and Phylogenetic Analysis of Toxocara Species in Dogs, Cattle and Buffalo in Egypt

Toxocara canis of dogs and Toxocara vitulorum of cattle and buffalo are nematode parasites that cause serious economic and public health problems all over the world. This study aims to provide molecular data to identify and distinguish between Toxocara spp. from dogs, cattle and buffalo in Egypt. Moreover, constructing a phylogeny and phylogenetic relationships among these Toxocara spp. were performed through an analytic study of ATPase-6, a mitochondrial gene; 12S, small subunit ribosomal RNA gene and ITS-2, the second internal transcribed spacer nuclear ribosomal gene. T. vitulorum from cattle and buffalo were found to be almost identical. The ATPase- 6 and 12S regions showed 87.78 % and 90.38 % nucleotide similarity between T. canis and T. vitulorum, while for the ITS-2 region, only 78.38 % was found. Analysis of the three studied genes revealed that each Toxocara spp. has distinct molecular characteristics. Moreover, it was revealed that these genes, especially the ITS-2 gene, are useful and sensitive molecular markers for classifying and studying the phylogenetic analysis and relationships among closely related Toxocara spp. All sequences obtained in this study were registered in the GenBank under the accession numbers: MG214149 -MG214157.

Phylogenetic relationships among Toxocara spp. and Toxascaris sp. from different regions of the world

Toxocara and Toxascaris are parasitic nematodes that infect canids and felids although species of the genus Toxocara also infect humans. This work aimed to establish the phylogenetic and phylogeographic relationship between specimens of T. canis, T. cati, T. malaysiensis and Toxascaris leonina and to evaluate the degree of host specificity. In total, 437 samples (adults and pools of eggs) were collected from canids and felids from eight countries. Parasites were identified by morphology, PCR linked Restriction Fragment Length Polymorphism (PCR-RFLP) and partial sequencing of the mitochondrial gene cox1. Phylogenetic trees were constructed and genetic distance among isolates was estimated. Based on the molecular characterization all worms were identified in agreement with their respective hosts with the exception of three samples; two from cats and one from dogs identified as T. canis and T. cati, respectively. There was no clear geographical clustering of the samples despite this study including parasites from three continents. This is the first study, to our knowledge, to use molecular methods to identify T. canis in cats and T. cati in dogs with host specificity being the most common finding. Our developed PCR-RFLP method was found to be a facile and reliable method for identifying Toxocara species.

Molecular data reveal cryptic speciation and host specificity in Toxascaris leonina (Nematoda: Ascarididae)

Toxascaris leonina (Ascarididae) is a cosmopolitan and polyxenical parasite whose host are canids and felids. To date, molecular phylogenetic studies included toxascarid representatives collected only from dogs or felids, therefore the intra-species differences between T. leonina collected from different host species has not been noticed. In this paper, we test the hypothesis of cryptic speciation in the T. leonina complex based on extended sequence data (ITS1, nad1, cox1) and individuals collected from dogs, felids and foxes. Phylogenetic analysis clustered T. leonina representatives into three well-supported clades depending on their host species, i.e. dogs and wolves, wild felids and foxes. Both genetic distances and the barcoding-gap analysis strongly support the species status of populations inhabiting different hosts. The results suggest additional genetic separation in felids. However, to determine the actual size of the Toxascaris complex, it would be necessary to analyse individuals collected from other canid and felid Toxascaris leonina host species.

Genetic Analysis of Toxocara Spp. in Stray Cats and Dogs in Van Province, Eastern Turkey

INTRODUCTION

Toxocara canis and Toxocara cati are roundworms of dogs and cats. The purpose of this study was to investigate the infection caused by these ascarids in cats and dogs, using microscopic and molecular analysis methods.

MATERIAL AND METHODS

Adult ascarids were gathered from the faeces of dogs and cats in Van province, in 2015-2016. Existing keys and PCR sequencing of the ITS-2 fragment were used to identify the morphological features of the parasite species.

RESULTS

It was observed that out of 20 adult ascarids, 17 and 3 were found to be Toxocara canis and Toxocara cati, respectively. The ITS-2 gene region was amplified by PCR to perform molecular analysis. Genotyping indicated that the dogs and cats were infected with T. canis and T. cati, respectively, and none had Toxascaris leonina.

CONCLUSION

To the best of our knowledge, this is the first report on the molecular characteristics of adult ascaridoid nematodes from cats and dogs in Turkey. The molecular approaches established in this study enable molecular identification and genetic structure studies of the ascaridoids.

Toxocariasis: a silent threat with a progressive public health impact

Background

Toxocariasis is a neglected parasitic zoonosis that afflicts millions of the pediatric and adolescent populations worldwide, especially in impoverished communities. This disease is caused by infection with the larvae of Toxocara canis and T. cati, the most ubiquitous intestinal nematode parasite in dogs and cats, respectively. In this article, recent advances in the epidemiology, clinical presentation, diagnosis and pharmacotherapies that have been used in the treatment of toxocariasis are reviewed.

Main text

Over the past two decades, we have come far in our understanding of the biology and epidemiology of toxocariasis. However, lack of laboratory infrastructure in some countries, lack of uniform case definitions and limited surveillance infrastructure are some of the challenges that hindered the estimation of global disease burden. Toxocariasis encompasses four clinical forms: visceral, ocular, covert and neural. Incorrect or misdiagnosis of any of these disabling conditions can result in severe health consequences and considerable medical care spending. Fortunately, multiple diagnostic modalities are available, which if effectively used together with the administration of appropriate pharmacologic therapies, can minimize any unnecessary patient morbidity.

Conclusions

Although progress has been made in the management of toxocariasis patients, there remains much work to be done. Implementation of new technologies and better understanding of the pathogenesis of toxocariasis can identify new diagnostic biomarkers, which may help in increasing diagnostic accuracy. Also, further clinical research breakthroughs are needed to develop better ways to effectively control and prevent this serious disease.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0437-0) contains supplementary material, which is available to authorized users.

First report of Toxocara cati in the domestic land snail Rumina decollata

The prospective role of the land snail Rumina decollata as a potential paratenic host of Toxocara cati for domestic cats was studied. R. decollata specimens and cats' feces were collected from the open spaces of a Buenos Aires city hospital. Cats' feces were analyzed and snails were digested to identify T. cati stages, by morphological and molecular analyses. T. cati larval eggs were recovered from 23.5% (4/17) of the sampled feces. Twenty percent of snail pools (5/25) were confirmed to be positive for Toxocara spp. third larval stage (L3) by PCR. The mean value of total larvae recovered per gram of snail in all positive pools was 5.1, with a maximum 33 L3/pool. This is the first report of T. cati infective larvae in R. decollata domestic snail as a paratenic host, since the relationship between infection in snails and in cats' feces could be demonstrated in a common environment.

Sequence variation in mitochondrial cox1 and nad1 genes of ascaridoid nematodes in cats and dogs from Iran

The study was conducted to determine the sequence variation in two mitochondrial genes, namely cytochrome c oxidase 1 (pcox1) and NADH dehydrogenase 1 (pnad1) within and among isolates of Toxocara cati, Toxocara canis and Toxascaris leonina. Genomic DNA was extracted from 32 isolates of T. cati, 9 isolates of T. canis and 19 isolates of T. leonina collected from cats and dogs in different geographical areas of Iran. Mitochondrial genes were amplified by polymerase chain reaction (PCR) and sequenced. Sequence data were aligned using the BioEdit software and compared with published sequences in GenBank. Phylogenetic analysis was performed using Bayesian inference and maximum likelihood methods. Based on pairwise comparison, intra-species genetic diversity within Iranian isolates of T. cati, T. canis and T. leonina amounted to 0-2.3%, 0-1.3% and 0-1.0% for pcox1 and 0-2.0%, 0-1.7% and 0-2.6% for pnad1, respectively. Inter-species sequence variation among the three ascaridoid nematodes was significantly higher, being 9.5-16.6% for pcox1 and 11.9-26.7% for pnad1. Sequence and phylogenetic analysis of the pcox1 and pnad1 genes indicated that there is significant genetic diversity within and among isolates of T. cati, T. canis and T. leonina from different areas of Iran, and these genes can be used for studying genetic variation of ascaridoid nematodes.

The complete mitochondrial genome of Toxascaris leonina: Comparison with other closely related species and phylogenetic implications

Adults of Toxascaris leonina (Nematoda: Ascarididae) live in the gastrointestinal tract of both dogs and cats, and cause significant economic losses and potential public health problem worldwide. Although many studies have given insights into this significant pathogen, to date, the complete mitochondrial (mt) genome sequence is still not available for T. leonina. Here, we sequenced the complete mt genome of T. leonina. This AT-rich (71.53%) mt genome (14,310bp) is circular and consists of 36 genes, including 12 genes for proteins, 2 genes for rRNA and 22 genes for tRNA. All mt genes of T. leonina are transcribed in the same direction. The gene order is the same as those of Ascaris spp. (Ascarididae), Toxocara spp. (Toxocaridae), Anisakis simplex and Contracaecum rudolphii B (Anisakidae), but distinct from that of Ascaridia spp. (Ascaridiidae). Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes by Bayesian inference (BI) showed distinct groups with high statistical support, and our data confirm that T. leonina is a member of the Ascarididae, and that this family is more closely related to the Toxocaridae rather than the Anisakidae within the Ascaridoidea. The determination of mt genome sequences of T. leonina provides novel genetic markers for studies into the systematics, population genetics and epidemiology of this parasite.

Comparison of functional gene annotation of Toxascaris leonina and Toxocara canis using CLC genomics workbench

The ascarids, Toxocara canis and Toxascaris leonina, are probably the most common gastrointestinal helminths encountered in dogs. In order to understand biological differences of 2 ascarids, we analyzed gene expression profiles of female adults of T. canis and T. leonina using CLC Genomics Workbench, and the results were compared with those of free-living nematode Caenorhabditis elegans. A total of 2,880 and 7,949 ESTs were collected from T. leonina and T. canis, respectively. The length of ESTs ranged from 106 to 4,637 bp with an average insert size of 820 bp. Overall, our results showed that most functional gene annotations of 2 ascarids were quite similar to each other in 3 major categories, i.e., cellular component, biological process, and molecular function. Although some different transcript expression categories were found, the distance was short and it was not enough to explain their different lifestyles. However, we found distinguished transcript differences between ascarid parasites and free-living nematodes. Understanding evolutionary genetic changes might be helpful for studies of the lifestyle and evolution of parasites.