Ascarid Species Research Articles

Morphological, ultrastructural, and phylogenetic analysis of Ascaridia columbae infecting domestic pigeons (Columba livia domestica).

Ascaridia species are the most common nematodes infecting pigeons. The current study investigated specific identity of nematode parasites collected from domestic pigeons (Columba livia domestica) in Al-Qassim Region, Saudi Arabia. Out of 354 pigeons, 13.3 % were infected with nematode parasites. The morphological structure and genetic relationship of nematode worms were studied using conventional methods (Light and scanning electron microscopes) coupled with the newly introduced molecular method. Microscopical and ultrastructure observations showed that the present nematode worms belong to the genus Ascaridia and have all the characteristic features of Ascaridia columbae. Moreover, Random Amplifier morphometric (RAPD) PCR analysis revealed that the present A. columbae had a close identity of up to 98.3 % to Ascaridia columbae JX624729 for Cox-1 gene regions, and up to 98.3 % to Ascaridia nymphii LC057210, and Ascaridia galli EF180058 for ITS1-5.8s- ITS2 rDNA gene regions. Phylogenetic analysis supported the placement of this Ascaridia species within Ascaridiidae family with close relationships to other nematode species obtained from GenBank. Finally, our study recommends using molecular analysis in helminths identification as the main methodology for correct identification especially in closely related species.

Absence of Polymorphisms in Codons 167, 198 and 200 of All Seven β-Tubulin Isotypes of Benzimidazole Susceptible and Resistant Parascaris spp. Specimens from Australia.

Benzimidazoles resistance is widespread in strongyle parasitic nematodes and associated with polym orphisms in the codons 167, 198 and 200 of isotype 1 β-tubulin (tbb-1). In ascarids, benzimidazole (BZ) resistance has rarely been reported and in none of these cases were any of these polymorphisms detected. Here, available genome and transcriptome data from WormBase ParaSite were used to compare the complete β-tubulin reservoirs of Parascaris univalens, Ascaris suum and Ascaris lumbricoides. Adult Parascaris spp. specimens collected in Australia from horses after BZ treatment (susceptible, n = 13) or surviving BZ treatment and collected after ivermectin treatment (resistant, n = 10) were genotyped regarding codons 167, 198 and 200 using Sanger sequencing. Phylogenetic analyses clearly showed that there are no one-to-one ascarid orthologs of strongyle tbb-1 genes. In the reference genomes, as well as phenotypically susceptible and resistant Parascaris spp. from Australia, six out of seven β-tubulin genes showed a BZ-susceptible genotype (F167, E198, F200). The only exception were the testis-specific β-tubulin D genes from all three ascarid species that encode tyrosine at codon 200. This was observed independently of the BZ-susceptibility phenotype of Parascaris spp. These data suggest that different mechanisms lead to BZ resistance in ascarid and strongyle nematodes.

Very low intraspecific sequence variation in selected nuclear and mitochondrial Parascaris univalens genes.

Equines were over decades considered to be infected by two morphologically virtually indistinguishable ascarid species, Parascaris univalens and Parascaris equorum. Reliable species discrimination is only possible using enzyme isoelectric focussing and karyotyping with P. univalens having one and P. equorum two chromosome pairs. However, presumably the complexity of both methods prevented their routine use in nearly all previous studies about prevalence and drug resistance of Parascaris spp. These have barely been performed on the species level although most studies stated presence of one or the other species. Recently, only P. univalens has been identified by karyotyping and the last published study identifying P. equorum dates back to 1989. In order to improve species-specific detection, molecular markers are required. Here, partial 12S rRNA, cytochrome oxidase I (COI) and complete internal transcribed spacer (ITS)-1 and-2 sequences were obtained from 24 karyotyped Parascaris specimens from Poland and 6 German specimens (not karyotyped) and used in phylogenetic analyses with orthologous sequences from GenBank. All karyotyped specimens were identified as P. univalens. In the phylogenetic analysis, they formed very homogenous clusters for all target genes and in a multi-locus analysis. Within this cluster, almost all sequences from GenBank were also included, no matter if they had been assigned to P. univalens or P. equorum. However, a small number of P. univalens ITS and COI sequences originating from donkeys from a single farm in China formed a highly supported sister cluster suggesting that they might represent another Parascaris genotype or species. Our data also strongly suggest that nearly all ITS and COI sequences previously deposited in GenBank and assigned to P. equorum actually represent P. univalens. The fact that significantly different sequences can be found in Parascaris spp. suggests that PCR-based species diagnosis will be possible once molecular markers have been identified for P. equorum from karyotyped specimens.

Molecular characterization of <i>Ascaridia galli</i> from Bangladesh and development of a PCR method for distinguishing <i>A. galli</i> from <i>Heterakis</i> spp.

We analyzed the nuclear ribosomal internal transcribed spacer (ITS) 1 and ITS2 sequences for Bangladesh isolates of Ascaridia galli, and we determined that the sequences were unreliable as molecular markers for distinguishing A. galli from other Ascaridia species, because the sequences showed high identity with that of A. columbae. However, the ITS1 sequences were available for designing PCR primers distinguishable between Ascaridia galli and Heterakis spp. Bangladesh isolates of A. galli constituted a monophyletic clade along with other geographical isolates in the cytochrome c oxidase subunit I (COI) phylogenetic tree, however, we could not clarify the phylogenetic relationships between A. galli and other Ascaridia spp., because their available sequences in GenBank were very few. The developed PCR method using DNA from A. galli and Heterakis spp. eggs would enable differential diagnosis of the individual infections in the future.

MICROSCOPIC AND MOLECULAR DIAGNOSIS OF Ascaridia spp. IN DOMESTIC PIGEONS(Columba livia domestica) IN BAGHDAD CITY,IRAQ

Ascaridiosis is a very important parasitic disease of birds, it is caused by Ascaridia. This study was conducted to identify the Ascaridia species by microscopic and molecular assay in Baghdad city. One hundred and sixty fecal samples were collected from domestic pigeons during the period from 1/1/ 2019 to 31/3/ 2019. Results showed that the rate of infection for Ascaridia spp. 15.62% by microscopic examination. Significant difference was observed in infection rates between males and females pigeons. Fifty samples randomly selected and subjected to molecular diagnosis of Ascaridia spp.. Molecular examination results, the total infection rate showed 16%(8/50). The eight positive PCR products were sequenced and deposited in Gene bank data base, phylogenic analysis demonstrated that 4 sequences belongs to Ascaridia galli ( MK918635.1, MK918636.1, MK918847.1, MK919081.1), while 2 (MK919199.1, MK919200.1) belong to Ascaridia nymphii and 2 (MK919207.1, MK919264.1) belong to Ascaridia numidae. It is the first study in Iraq to diagnosis of Ascaridia nymphii and Ascaridia numidae in domesticed pigeons by using conventional PCR.

Ascarids exposed: a method for in vitro drug exposure and gene expression analysis of anthelmintic naïve Parascaris spp.

Ascarid parasites infect a variety of hosts and regular anthelmintic treatment is recommended for all species. Parascaris spp. is the only ascarid species with widespread anthelmintic resistance, which allows for the study of resistance mechanisms. The purpose of this study was to establish an in vitro drug exposure protocol for adult anthelmintic-naïve Parascaris spp. and report a preliminary transcriptomic analysis in response to drug exposure. Live worms were harvested from foal necropsies and maintained in RPMI-1640 at 37 °C. Serial dilutions of oxibendazole (OBZ) and ivermectin (IVM) were prepared for in vitro drug exposure, and worm viability was monitored over time. In a second drug trial, worms were used for transcriptomic analysis. The final drug concentrations employed were OBZ at 40.1 μm (10 μg mL-1) and IVM at 1.1 μm (1 μg mL-1) for 24 and 3 h, respectively. The RNA-seq analysis revealed numerous differentially expressed genes, with some being potentially related to drug detoxification and regulatory mechanisms. This report provides a method for in vitro drug exposure and the phenotypic responses for Parascaris spp., which could be extrapolated to other ascarid parasites. Finally, it also provides preliminary transcriptomic data following drug exposure as a reference point for future studies of Parascaris spp.

Antigen detection: Insights into Toxocara and other ascarid infections in dogs and cats.

Detection of ascarid excreted or secreted (E/S) molecules is an alternative approach to the identification of infection by egg flotation. E/S molecules serve as direct markers for the ascarid nematode commonly found in cats and dogs (Toxocara spp., Toxascaris leonina and Baylisascaris procyonis). The nematode derived E/S material mixes with the intestinal contents of the host animal and is available for detection as a coproantigen in the host's faeces. Antigen capture immunological techniques allow sensitive coproantigen detection. Different patterns of antigen to egg agreement are demonstrated in an experimental Toxocara canis infection throughout the prepatent, patent, and post-treatment phases. Examination of faecal samples from a large field population of dogs and cats tested for both egg shedding and antigen indicates that more infections were identified by antigen. Host age influences the agreement of antigen and Toxocara egg results. Older dogs and cats were less likely to have a patent infection (egg positive and antigen positive) result pattern. An egg observation in the absence of antigen detection may indicate a spurious egg. The impact of spurious eggs was further examined by comparisons of cohorts of dogs separated by presence or absence of a pseudoparasite observation or by egg semi-quantification bin. Lastly, the antigen to egg agreement was calculated for other ascarid species.

Molecular characterization of β-tubulin gene associated with benzimidazole resistance in larvae of field isolates of Parascaris (Nematoda: Ascarididae).

Since the past 2decades, an increasing number of resistance to the Benzimidazoles (BZs) have been reported in nematode parasites of livestock. More recently, detection of single-nucleotide polymorphisms (SNPs) at codons of 167, 198 or 200 of the β-tubulin gene has been attributed to the occurrence of resistance. In the present study, we investigated the presence of those SNPs in the β-tubulin isotype-1 gene in different isolates of Parascaris in horse. Also, the mitochondrial (mt) and ribosomal genes were sequenced for species confirmation of the isolates. The analysis of sequences inferred from COII gene confirmed that those isolates were P. equorum. The distance between mt genes obtained here and several ascarid species in equids and other hosts suggests the need for the combination of more genetic data with morphologic and other diagnostic measures. The analysis on β-tubulin isotype-1 gene revealed no resistance-related SNPs or substitutions at the expected codon positions and selection pressure with BZs has not occurred for Parascaris worms. Although the molecular data showed the susceptibility of Parascaris isolates against BZs, other mechanisms of resistance should be also investigated to confirm the validity of molecular results.

Co-expulsion of Ascaridia galli and Heterakis gallinarum by chickens

Worm expulsion is known to occur in mammalian hosts exposed to mono-species helminth infections, whilst this phenomenon is poorly described in avian hosts. Mono-species infections, however, are rather rare under natural circumstances. Therefore, we quantified the extent and duration of worm expulsion by chickens experimentally infected with both Ascaridia galli and Heterakis gallinarum, and investigated the accompanying humoral and cell-mediated host immune responses in association with population dynamics of the worms. Results demonstrated the strong co-expulsion of the two ascarid species in three phases. The expulsion patterns were characterized by non-linear alterations separated by species-specific time thresholds. Ascaridia galli burden decreased at a daily expulsion rate (e) of 4.3 worms up to a threshold of 30.5 days p.i., followed by a much lower second expulsion rate (e = 0.46), which resulted in almost, but not entirely, complete expulsion. Heterakis gallinarum was able to induce reinfection within the experimental period (9 weeks). First generation H. gallinarum worms were expelled at a daily rate of e = 0.8 worms until 36.4 days p.i., and thereafter almost no expulsion occurred. Data on both humoral and tissue-specific cellular immune responses collectively indicated that antibody production in chickens with multispecies ascarid infections is triggered by Th2 polarisation. Local Th2 immune responses and mucin-regulating genes are associated with the regulation of worm expulsion. In conclusion, the chicken host is able to eliminate the vast majority of both A. galli and H. gallinarum in three distinct phases. Worm expulsion was strongly associated with the developmental stages of the worms, where the elimination of juvenile stages was specifically targeted. A very small percentage of worms was nevertheless able to survive, reach maturity and induce reinfection if given sufficient time to complete their life cycle. Both humoral and local immune responses were associated with worm expulsion.

Ascaridia galli isolates with ITS1-5.8rRNA-ITS2 fragment homologous to Ascaridia columbae.

Ascaridia (A.) galli is one of the most commonly occurring nematodes in poultry worldwide, often in hens and broiler chickens. The infection with Ascaridia galli in free-range chickens was even 70%. There is not much information about A. galli genetic features. The present study was conducted to assess the genetic diversity of A. galli isolated from hens in Poland by analyzing the nucleotide sequence of the region ITS1-5.8rRNA-ITS2 and to define its homology within the family Ascaridiidae. Adult A. galli were collected from the intestines of naturally infected hens from two flocks of free-run laying hens from the Wielkopolska region in Poland. From all parasites an identical ITS1-5.8rRNA-ITS2 sequence was obtained, which was homologous in 99% with A. columbae (JQ995321.1) sequence. The high homology sequences of A. galli (KX683286) from Poland and A. columbae (JQ995321.1) isolate from the USA, support the observations of other authors suggesting that A. galli and A. columbae might be closely related. It is the first whole ITS1-5.8rRNA-ITS2 of A. galli in the GenBank database, so there is not enough data for detailed phylogenetic analysis of A. galli. Detailed genetic analysis is necessary to get better insight into the birds' Ascaridia species.

New record of Ascaridia nymphii (Secernentea: Ascaridiidae) from macaw parrot, Ara chloroptera, in China

Present study was performed to identify the species of ascarids from macaw parrot, Ara chloroptera, in China. Total 6 ascarids (3 males and 3 females) were collected in the feces of 3 macaws at Guangzhou Zoo in Guangdong Province, China. Their morphological characteristics with dimensions were observed under a light microscope, and their genetic characters were analyzed with the partial 18S rDNA, ITS rDNA and nad4 gene sequences, respectively. Results showed that all worms have no interlabia but male worms have two alate spicules, well-developed precloacal sucker and a tail with ventrolateral caudal alae and 11 pairs of papillae. The partial 18S rDNA, ITS rDNA and nad4 sequences were 831bp, 1015bp and 394bp in length, respectively. They showed the highest similarity of 99.8% (18S rDNA) with Ascaridia nymphii, 93.8% identities (ITS rDNA) with A. columbae and 98.5% to 99.5% identities (nad4) with Ascaridia sp. from infected parrot. All Ascaridia nematodes from the macaws were clustered into one clade and formed monophyletic group of Ascaridia with A. columbae and A. galli in two phylogenetic trees. It is observed that the combining morphological and sequencing data from three loci, the present Ascaridia species was identified as Ascaridia nymphii, which is the first record of A. nymphii from macaw parrot in China.

Ultrastructure, Morphological Differentiation and Pathological Changes of Ascaridia species in Pigeons

Ultrastructure, Morphological Differentiation and Pathological Changes of Ascaridia species in Pigeons

Enzyme-linked immunosorbent assays for coproantigen detection of Ancylostoma caninum and Toxocara canis in dogs and Toxocara cati in cats

We report the development and field validation of 2 ELISAs for the detection of Ancylostoma caninum or Toxocara canis coproantigens in the feces of dogs with experimental and natural infections, and evidence of cross-reactivity with respective feline counterparts. A. caninum-specific coproantigens were detected in feces of experimentally infected dogs starting at 9 d post-infection (dpi), whereas eggs were not seen until 23 dpi. T. canis-specific coproantigens were detected in 3 of 5 experimentally infected dogs by 31 dpi, and 4 of the 5 animals by 38 dpi. T. canis eggs were seen in feces of 4 of the 5 animals by 38 dpi. One dog had delayed coproantigen detection and low egg output. Additionally, 817 canine and 183 feline fecal samples from naturally infected animals tested by flotation were subjected to coproantigen ELISA testing. Of these 1,000 canine and feline samples, 13 and 23 samples, respectively, were positive for "hookworm" or "roundworm" eggs; 19 and 26 samples were ELISA positive, respectively. The T. canis ELISA detected T. cati coproantigen in cat fecal samples. Discrepant ELISA and flotation results were obtained for 16 hookworm- and 13 roundworm-positive samples. Re-examination of the egg-positive, ELISA-negative samples indicated several instances of possible misidentification or coprophagy, whereas detection of antigen in samples without egg observations is likely a reflection of true infection status with egg shedding below detection levels. There is good indication, based on accumulated field data, that these antigen tests also detect other hookworm and ascarid species.

Gastrointestinal parasitism in local and exotic breeds of chickens reared in Gwagwalada Guinea Savannah zone of Nigeria

The present study was carried out to establish the gastrointestinal parasites in local and exotic breeds of chickens reared in Gwagwalada, Guinea Savannah Zone of Nigeria. It was conducted between July and September, 2014. Two hundred and eighty (280) faecal samples from local and exotic breeds of chicken and 50 intact whole intestines were collected randomly from seven (7) major towns (Gwagwalada, Dobi, Gwako, Giri, Anagada, Tungan Maje and Zuba) in Gwagwalada Area council and examined for gastrointestinal parasites using flotation and sedimentation methods. Six (6) different gastrointestinal parasite eggs and oocytes were identified in 42.5% of the birds examined. Of these parasites, Ascaridia species was found to be the most prevalent (36.1%) among the chickens. Other parasites encountered include; Eimeria oocytes (34.5%), Heterakis species (12.6%), Rallietina species 10.1%; Capillaria species (4.2%) and Syngamus species (2.5%). There were mixed infection of 1.4% among the infected birds. Interestingly, none of the birds examined was infected with trematodes There was no significant difference (p>0.05) in prevalence rate of infection between the local and exotic breeds of chickens. Although males had a higher prevalence of infection than the females in both breeds, there was no significant difference (p>0.05) in the prevalence of infection among sexes. However, there was significant difference (P<0.05) between the age groups, with highest infection occuring in growers (46.2%). 20 (40%) of the 50 intact whole intestines screened were positive for gastrointestinal parasites by gross examination of intestinal tract. Out of the 20 positive, 12 were nematodes, 3 cestodes and remaining 5 were mixed infections. Therefore, sustainable ways of controlling these parasites at a particular age and further studies on the prevalence of gastrointestinal parasites in chicken need to be elucidated for improved intensive egg and poultry meat productionsKeywords: Chickens, Exotic, Gastrointestinal, Local, Parasites, Prevalence

Ascaridia nymphii n. sp. (Nematoda: Ascaridida) from the alimentary tract of a severely emaciated dead cockatiel Nymphicus hollandicus.

This report describes Ascaridia nymphii n. sp., a new species isolated from the alimentary tract of cockatiel Nymphicus hollandicus in Japan. More than 63 nematodes were found in the formalin-fixed small intestine, ventriculus, proventriculus and crop of a 48-day-old young cockatiel that died after exhibiting severe emaciation. No nematode eggs were observed in the faecal examination performed while the cockatiel was alive, but Cryptosporidium oocysts were found. The intestinal mucosa was damaged considerably. Male worms had two alate spicules, well-developed precloacal sucker and a tail with ventrolateral caudal alae and mainly 11 pairs of papillae. Nuclear partial (813 bp) 18S ribosomal RNA gene (18S rDNA) sequences obtained from two female samples were mutually identical. They respectively showed 99.1 and 98.6% identities to those from Ascaridia numidae and Ascaridia galli. Phylogenetic analysis using this locus indicated the present nematode as Ascaridia species. The mitochondrial NADH dehydrogenase subunit 2 gene (nad2) sequences obtained for four samples were mutually identical. They respectively showed 98.7, 85.7 and 82.2% identities with those from Ascaridia columbae, Ascaridia sp. and A. galli. Combining the morphological and sequencing data from two loci, the present nematode was identified as A. nymphii n. sp., which is closely related with A. columbae. This report is the first of a study examining the distribution of Ascaridia species in captive parrots in Japan. This study also identified the trachea and cloaca, like Cryptosporidium baileyi, as the possible location of Cryptosporidium avian genotype V in avian hosts.

A method to evaluate relative ovicidal effects of soil microfungi on thick-shelled eggs of animal-parasitic nematodes

Thick-shelled eggs of animal-parasitic ascarid nematodes can survive and remain infective in the environment for years. The present study evaluated a simple in vitro method and evaluation scheme to assess the relative effect of two species of soil microfungi, Pochonia chlamydosporia Biotype 10 and Purpureocillium lilacinum Strain 251 (Ascomycota: Hypocreales), on the development and survival of eggs of faecal origin of three ascarid species, Ascaridia galli (chicken roundworm), Toxocara canis (canine roundworm) and Ascaris suum (pig roundworm). Ascarid eggs were embryonated on water agar with or without a fungus, and the resulting viability of the eggs was evaluated on days 7, 14, 21, 28, 35 and 42 post exposure (pe) by observing eggs in situ. On days 7–42 pe, P. chlamydosporia had reduced the viability of A. galli and T. canis eggs by 64–86% and 26–67%. Corresponding reductions for P. lilacinum Strain 251 were only 15–29% and 4–28%. In contrast, A. suum eggs were extremely resistant to both fungi (2–4% reduction). The differences in results are likely due to different morphologies and chemistry of the egg shell of the three ascarid species. The current in vitro method and evaluation criteria allow for a simple, repeatable and non-invasive evaluation of the ovicidal effects of microfungi. This study demonstrates that P. chlamydosporia Biotype 10 may be utilised as a biocontrol agent to reduce A. galli and T. canis egg contamination of the environment.

A new ascarid species in cynodont coprolite dated of 240 million years

Cynodonts represent the transition from reptiles to mammals. They are classified as synapsids, or tetrapod animals with mammalian characteristics. We present here the finding of helminth eggs in a coprolite identified as of cynodont origin dated of nearly 240 million years. Microscopy revealed the presence of very well preserved intestinal parasite eggs. Up to now we identified an ascarid egg by morphological characteristics. Based on a previous description of the new genus Ascarites Poinar Jr and Boucot 2006 in coprolites of iguanodons from Belgium, we propose a new species, Ascarites rufferi n.sp. in cynodonts, a host that inhabited the Southern Region of Brazil in the Triassic period.

New parasite in a coprolite of 240 million years, biogeography of fossil coelacanths, and the influence of air pollutants in a coastal area of northeastern Brazil

(AABC) publishes several papers on paleontology. Among them is the study of Priscilla da Silva (Fundacao Oswaldo Cruz) and colleagues who have made quite an interesting discovery: a new parasite in a coprolite of 240 million years (Da Silva et al. 2014). Coprolites or fossilized feces are not particularly rare, being constantly recovered during paleontological excavations, for all in areas that represent ancient shallow seas, lagoons or lakes (e.g., Vila Nova et al. 2011), where often they can be the most common fossil found. Occasionally they are also found in terrestrial environments (Souto 2000). Nevertheless they are not very commonly reported upon, possibly due to the fact that it is very hard to be sure which kind of animal produced them. Notwithstanding, it is quite an important material to be studied since they provide some important information regarding an animal´s diet.In the case of the specimen studied by Da-Silva and colleagues, they could attribute a coprolite to a primitive herbivorous cynodont, even though they were not able to precise which species. The material was recovered from layers of the Triassic Santa Maria Formation in Rio Grande do Sul at a site called Cortado. Being perhaps one of the few cases of a primitive cynodont coprolite, the most important aspect of this discovery was the identification of parasite eggs that the authors have attributed to a new ascarid species. It would be interesting to proceed with this kind of study in other coprolites of the Santa Maria Formation that might reveal more of such parasite, and try to establish if it was endemic to this region of southern Brazil during this geologic period.Another interesting contribution published in the present issue of the AABC is on the distributional pattern of an extinct group of coelacanths. This group of lobe-finned fishes is presently represented by only two species found in the coastline of the Indian Ocean and Indonesia (Holder et al. 1999), but in deep time they showed quite some diversity (Johanson et al. 2006, Miguel et al. 2014). Raphael Miguel (Universidade do Estado do Rio de Janeiro) and colleagues have reviewed the distribution of the extinct coelacanth group called Mawsoniidae. Although known since the Triassic, those fishes are particularly common in Cretaceous deposits (Miguel et al. 2014). Biogeographic studies are quite interesting since they can help explain why the

In vitrostudy on targeting developmental embryonation pattern of eggs of ascarid species of wild animals

The present study was aimed to investigate the time intervals required by the eggs of two ascarid species -Baylisascaris transfuga retrieved from Melursus ursinus (Sloth bear), and Toxascaris leonina, retrieved from Panthera leo persica (Asiatic/Indian lion) to reach infective stages at controlled temperature (27±1°C) in 0.4% formalin solution as well as in faecal samples as such. The incubated material revealed that the eggs advanced to two-cell stage at day 2 and 3 post-incubation in case of T. leonina and B. transfuga, respectively, in formalin solution as well as in faecal samples. The final infective stages having 2nd stage larvae inside the eggs were observed at day 12 and 9 post incubation in 0.4% formalin solution and at day 14 and 9 post-incubation in faecal samples in case of B. transfuga and T. leonina, respectively. To check the reoccurrence of infection of these parasites having direct life cycle, better management practices involving anthelmintic therapy of the infected individuals with complete disinfection of the habitat area should be carried out.

Sequence variability in three mitochondrial genes among four roundworm species from wild animals in China

Sequence variability in three mitochondrial DNA (mtDNA) regions, namely portions of cytochrome c oxidase subunit 1 (pcox1), NADH dehydrogenase subunit 1 (pnad1) and NADH dehydrogenase subunit 4 (pnad4), for Toxocara canis. Baylisacaris transfuga. Ascaris suum and Parascaris equorum from Canis lupus. Ursus thibetanus. Sus scrofa and Equus burchelli in China were examined. The lengths of the sequences of pcox1, pnad1 and pnad4 were 711 bp, 648 bp and 666 bp, respectively. No intra-species differences were detected in pcox1 for the four examined ascarid species, in pnad1 for T. canis. A. suum and P. equorum, and in pnad4 for B. transfuga and P. equorum. Sequence differences in pnad4 for six roundworm samples of T. canis and P. equorum were 0–0.1% and 0–0.3%, respectively, and were 0–0.3% in pnad1 for six roundworm samples isolate of B. transfuga. The inter-specific sequence differences among four species were 8.7–12.4% for pcox1, 13.9–17.7% for pnad1, and 14.0–25.7% for pnad4. Phylogenetic analyses suggested that the three mtDNA fragments could be used to identify ascarid species in families Ascaridiae and Toxocaridae.