Setaria digitata is a filarial parasite that causes fatal cerebrospinal nematodiasis in goats, sheep and horses, resulting in substantial economic losses in animal husbandry in the tropics. Due to its close resemblance to Wuchereria bancrofti, this nematode is also frequently used as a model organism to study human lymphatic filariasis. This review highlights numerous insights into the morphological, histological, biochemical, immunological and genetic aspects of S. digitata that have broadened our understanding towards the control and eradication of filarial diseases.

Vietnam is recognized to be endemic for fasciolosis. However, most of the available publications have not been published in international journals. This review is based on national and international Vietnamese publications and highlights the current status of fasciolosis in Vietnam. It also provides some information available for neighbouring countries. Updated data on responsible species, distribution, transmission and control aspects are summarized. The central region of Vietnam is reported as being highly endemic for fasciolosis, with a high number of human patients (more than 20,000 in 2011). Fasciola gigantica is reported to be the main species in Vietnam. However, hybrids between F. gigantica and F. hepatica were identified. Both humans and animals are infected by the ingestion of raw vegetables and possibly contaminated drinking water. Three lymnaeid snail species (Austropeplea viridis, Radix auricularia and Radix rubiginosa) may act as intermediate hosts of Fasciola spp. However, due to the likely misidentification of snail species and cercariae during the past decade the critical analysis of published data is difficult. A better understanding of transmission aspects of fasciolosis would allow the implementation of preventive measures of this important neglected zoonotic disease.

The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5–72% for pcox1, 73.7–74.2% for pnad1 and 58–58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0–1.6% for pcox1, 0–1.9% for pnad1 and 0–1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1–12.5%, 13.3–17.7% and 8.5–18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum.

One new species of the family Nordiidae Jairajpuri & Siddiqi, 1964 from the enclosure grassland of Qinghai Province, China, Heterodorus qinghaiensis n. sp., is described and illustrated. The new species is characterized by the slender body, 1.29–1.46 mm in length; the granular lateral chord with numerous large depression plaques throughout its entirety; the lip region offset by a distinct depression; amphid goblet-shaped with aperture about half to two-thirds of corresponding body diameter; odontostyle 11–13 μm long; rod-like odontophore without basal flanges; pharyngeal basal expansion about one-third of the total neck length; didelphic genital system containing sperm; ovaries generally not reaching the sphincter level; vulva transversed and sclerotized; female tail conoid with round terminus; 3–5 spaced ventromedial supplements and spicule 32–41 μm long. It is close to H. liangi (Ahmad, Wu & Shaheen, 2002) Andrássy, 2009, H. brevidentatus (Thorne, 1939) Andrássy, 2009, H. monticola Andrássy, 2011, H. morgensis (Loof, 1988) Andrássy, 2009 and H. meghalayensis (Mushtaq, Baniyamuddin & Ahmad, 2007) Andrássy, 2009 in having inconspicuous or no lateral body pores, smaller odontostyle and ventrally curved tail.

Adult Galba truncatula ( ≥ 4 mm in shell height) were collected from 135 habitats for 3 years (2012–2014) to identify parasite species via the study of cercariae, and to determine the prevalence of each digenean infection in relation to the type of snail habitat (six types). A total of 323 infected snails and ten digenean species were noted in the bodies of 11,025 G. truncatula after their dissection. Snails with Calicophoron daubneyi and/or Fasciola hepatica were found in 20.7% and 12.5% of the habitats, respectively, and most of these infected snails were collected from rainwater-draining furrows and pools in meadows. The percentages were lower for snails with Echinostoma revolutum (9.6% of habitats) and Haplometra cylindracea (7.4%), and were less than 5% for those parasitized by any of the other five species of digenean. The highest prevalence of all digenean infections was noted in pools (9.4%), followed by furrows located in meadows (8.3%) and ponds (5.1%). The prevalence noted for each digenean infection varied with the type of habitat. In furrows located in meadows, the infection rate of C. daubneyi in snails (3.5%) was significantly higher than that of F. hepatica (2.2%). In pools, values greater than 1.5% were noted for C. daubneyi, H. cylindracea and Opistoglyphe ranae. In ponds, E. revolutum was the dominant species (prevalence, 2.5%). Parasite species richness in G. truncatula was greater in the Brenne Natural Regional Park than in the nearby region of Limousin (ten instead of eight). The distribution and prevalence of each parasite species were dependent on the type and location of each snail habitat.

This paper focuses on the species diversity among the Trichostrongylidae Leiper, 1912 (Nematoda: Strongylida), and complexity of the family systematics. Polymorphism (subfamilies: Ostertagiinae, Cooperiinae and Haemonchinae), the presence of cryptic species (genus: Teladorsagia) and hybridization (genera: Cooperia, Haemonchus and Ostertagia) are presented and discussed, considering both morphological and molecular evidence. Some of these phenomena are common, nevertheless not sufficiently understood, which indicates the need for expanding the current state of knowledge thereof. Within the Trichostrongylidae, species distinction supported merely by morphological features is difficult, and requires confirmation by means of molecular methods. The parasitic nematode taxonomy is complicated mainly by the genus Teladorsagia, but complexity may also be expected among other Ostertagiinae (e.g. in the genera Ostertagia and Marshallagia). The data presented here show that the members of the Trichostrongylidae can significantly complicate unambiguous species identification. Hence, it is essential to consider the phenomena mentioned, to gather valid and comparable data on the biodiversity of this family.

Three species of belonid fish, Belone belone gracilis Lowe, 1839, Belone svetovidovi Collette & Parin, 1970 and Tylosurus acus imperialis (Rafinesque, 1810), caught off the eastern Tunisian coast were infected with eight species of Digenea. Among these, four species were commonly found in B. b. gracilis and are new host records for B. svetovidovi. They are: Lecithostaphylus retroflexus (Molin, 1859), Tergestia acanthocephala (Stossich, 1887) Stossich, 1899 and Aponurus laguncula Looss, 1907 in the intestine, and the metacercaria Condylocotyla pilodora Pearson and Prévot, 1985 in the pericardial sac. Four other digenean species were recorded from T. a. imperialis: Lecithostaphylus tylosuri Châari et al., 2013 and Tetrochetus coryphaenae Yamaguti, 1934 in the intestine, Oesophagotrema mediterranea Châari et al., 2011 in the oesophagus and vomer teeth, and Sclerodistomoides pacificus Kamegai, 1971 in the gall bladder. Tetrochetus coryphaenae and S. pacificus represent new host and geographical records. The spatial variation of digenean parasites within belonid host species is discussed.

During a non-targeted survey for entomopathogenic nematodes in South Africa, a new species of Steinernema was isolated from a soil sample collected from underneath a guava tree, close to the shore at Jeffrey's Bay. The nematode was isolated by means of the insect-baiting technique using last-instar larvae of Galleria mellonella. It is described herein as Steinernema jeffreyense n. sp. The nematode can be separated from other described, closely related species in terms of the morphological and morphometric characteristics of the different life stages, and in terms of the characterization and phylogeny of DNA sequences of the internal transcribed spacer (ITS) rDNA of the 18S gene, and of the D2D3 region of the 28S rDNA gene. The new species is placed molecularly in the arenarium–glaseri–karii–longicaudatum group characterized by the following morphological characters: infective third-stage juvenile with a body length of 926 (784–1043) μm, distance from head to excretory pore of 87 (78–107) μm, tail length of 81 (50–96) μm, with an E% of 109 (86–169), and eight evenly spaced ridges (i.e. nine lines) in the middle of the body. First-generation males have a spicule length of 88 (79–95) μm and gubernaculum length of 57 (51–61) μm. Male mucron is absent in both generations. First-generation females have an asymmetrical protuberance and a short, double-flapped epiptygmata, with both flaps directed to the front. The tail of the first-generation female is shorter than the anal body width, with a mucron on the dorsal tail tip, with D% = 78 (59–99). Cross-hybridization with S. khoisanae, S. tophus and S. innovationi showed the new species to isolate reproductively from the others. The analyses of ITS rDNA and D2D3 sequence of the 18S and 28S rDNA genes support the studied nematode isolate to be a valid new species belonging to the ‘glaseri’ group (Clade V).

Symbiotic bacteria are a common feature of many animals, particularly invertebrates, from both aquatic and terrestrial habitats. These bacteria have increasingly been recognized as performing an important role in maintaining invertebrate health. Both ecto- and endoparasitic helminths have also been found to harbour a range of bacterial species which provide a similar function. The part symbiotic bacteria play in sustaining homeostasis of free-living invertebrates exposed to anthropogenic pressure (climate change, pollution), and the consequences to invertebrate populations when their symbionts succumb to poor environmental conditions, are increasingly important areas of research. Helminths are also susceptible to environmental stress and their symbiotic bacteria may be a key aspect of their responses to deteriorating conditions. This article summarizes the ecophysiological relationship helminths have with symbiotic bacteria and the role they play in maintaining a healthy parasite and the relevance of specific changes that occur in free-living invertebrate–bacteria interactions under anthropogenic pressure to helminths and their bacterial communities. It also discusses the importance of understanding the mechanistic sensitivity of helminth–bacteria relationships to environmental stress for comprehending the responses of parasites to challenging conditions.

An investigation into the potential for transmission of gastrointestinal helminths from wild hogs to livestock and humans was prompted by concerns of recreational wild-hog hunting in the Caribbean region and the recent practice, by livestock farmers in Jamaica, of co-rearing wild and domesticated swine. Thirty-one wild hogs from the Hellshire Hills, a dry limestone forest in southern Jamaica, were necropsied during the period June 2004 to August 2006. Thirteen of the captured animals were male and 18 female. Four species of adult helminths were recovered from the gastrointestinal tracts of the wild hogs: Hyostrongylus rubidus (77%), Globocephalus urosubulatus (48%), Oesophagostomum dentatum (42%) and Macroacanthorhynchus hirudinaceus (77%). Two (6.2%), ten (32.2%) and 18 (58.0%) hogs harboured one, two and three species of helminths, respectively. Mean infection intensities varied from 8.1 for M. hirudinaceus, to 115.5 for O. dentatum. There was no association between any of the recovered helminths and sex of the host; however, a multivariate analysis indicated a positive association between the prevalence of G. urosubulatus and host age (odds ratio (OR) = 6.517). Domesticated hogs co-reared with wild hogs are potentially at risk of infection with all four helminths, while wild-hog hunters and pig farmers may be exposed to M. hirudinaceus.

Ancylostoma ceylanicum is a common zoonotic nematode. Cats act as natural reservoirs of the hookworm and are involved in transmitting infection to humans, thus posing a potential risk to public health. The prevalence of feline A. ceylanicum in Guangzhou (South China) was surveyed by polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP). In total, 112 faecal samples were examined; 34.8% (39/112) and 43.8% (49/112) samples were positive with hookworms by microscopy and PCR method, respectively. Among them, 40.8% of samples harboured A. ceylanicum. Twelve positive A. ceylanicum samples were selected randomly and used for cox 1 sequence analysis. Sequencing results revealed that they had 97–99% similarity with A. ceylanicumcox 1 gene sequences deposited in GenBank. A phylogenetic tree showed that A. ceylanicum isolates were divided into two groups: one comprising four isolates from Guangzhou (South China), and the other comprising those from Malaysia, Cambodia and Guangzhou. In the latter group, all A. ceylanicum isolates from Guangzhou were clustered into a minor group again. The results indicate that the high prevalence of A. ceylanicum in stray cats in South China poses a potential risk of hookworm transmission from pet cats to humans, and that A. ceylanicum may be a species complex worldwide.

Leucine aminopeptidase (LAP) and cathepsin L1 (CL1) are important enzymes for the pathogenesis and physiology of Fasciola hepatica. These enzymes were analysed in silico to design a chimeric protein containing the most antigenic sequences of LAP (GenBank; AAV59016.1; amino acids 192–281) and CL1 (GenBank CAC12806.1; amino acids 173–309). The cloned 681-bp chimeric fragment (rFhLAP-CL1) contains 270 bp from LAP and 411 bp from CL1, comprising three epitopes, DGRVVHLKY (amino acids 54–62) from LAP, VTGYYTVHSGSEVELKNLV (amino acids 119–137) and YQSQTCLPF (amino acids 161–169) from CL1. The ~25 kDa rFhLAP-CL1 chimeric protein was expressed from the pET15b plasmid in the Rosetta (DE3) Escherichia coli strain. The chimeric protein rFhLAP-CL1, which showed antigenic and immunogenic properties, was recognized in Western blot assays using F. hepatica-positive bovine sera, and induced strong, specific antibody responses following immunization in rabbits. The newly generated chimeric protein may be used as a diagnostic tool for detection of antibodies against F. hepatica in bovine sera and as an immunogen to induce protection against bovine fasciolosis.

Asexually proliferating Taenia crassiceps (Zeder, 1800) metacestodes isolated within past decades have been successfully sub-cultured under experimental conditions using Mus musculus Linnaeus, 1758 mice. However, during their development, morphological irregularities of scolex structures have been reported in two of the three strains of this cestode species maintained in mice – ORF and KBS. The main goal of this work is to describe the abnormalities observed in a sample of 118 cysticerci of the third T. crassiceps strain used at present – WFU. Morphological abnormalities were detected in 39.8% of the evaginated scoleces; they consisted of supernumerary suckers (n= 2), duplicated (n= 2) or absent rostellum (n= 1), as well as absent or aberrant (n= 29) hooks, which were significantly shorter when compared to the large and short hook lengths referred to in the literature.

Up to six nematode species were identified from 86 specimens of the yellow-necked field mouse Apodemus flavicollis from three mountainous localities known as Avala, Cer and Liškovac in Serbia. The highest prevalence of infection of 97% was recorded from Mt. Avala. Only one nematode species, Syphacia frederici, occurred in all three localities. There was complete overlap in nematode species from Mts. Avala and Liškovac, whereas the taxonomic distinctness of Mt. Cer was seen in the presence of the insect-transmitted species Rictularia proni. Locality was a statistically significant factor in all the best-fitted generalized linear models of variation in abundances. The highest level of both species richness and parasite alpha diversity (Shannon's H= 1.47) was found in the easternmost Mt. Liškovac, whereas the diversity indices were lowest for the westernmost Mt. Cer (Shannon's H= 0.48). In view of this geographical difference, the beta diversity indices were calculated along a west to east longitudinal gradient.

Populations of the lizard Darevskia rudis (Bedriaga, 1886) from northern Anatolia were examined for intestinal parasites in adult specimens. One cestode, Nematotaenia tarentolae López-Neyra, 1944 and four nematode species, Spauligodon saxicolae Sharpilo, 1962, Skrjabinelazia hoffmanni Li, 1934, Oswaldocruzia filiformis (Goeze, 1782) and Strongyloides darevskyi Sharpilo, 1976, were found. Three of these nematodes, S. saxicolae, S. hoffmanni and S. darevskyi are suggested to be part of a module in the network of Darevskia spp. and their parasites. Only one, S. darevskyi, was identified as a Darevskia spp. specialist. The very low infection and diversity parameters are indicative of the depauperate helminth communities found in this lacertid lizard, falling among the lowest within the Palaearctic saurians. Nevertheless these values are higher than those found in parthenogenetic Darevskia spp. Interpopulation variation in the intensity of S. saxicolae and N. tarentolae is attributable to local changes in ecological conditions. On the other hand, parasite abundance and richness increased in the warmer localities, while the effect of lizard sex and size on infection was negligible. The structure of these helminth communities in D. rudis are compared with those observed in other European lacertid lizards.

The Echinococcus granulosus tapeworm is responsible for cystic echinococcosis (CE), a zoonotic disease with worldwide distribution. The life cycle of the parasite is mainly domestic and takes place between dogs and livestock species. A slaughterhouse survey was conducted in 2012 in the Republic of Moldova in order to estimate the prevalence of CE. A total of 1525 cattle, 5580 sheep and 12,700 pigs were surveyed. No CE infection was observed in pigs, while prevalence was estimated at 59.3% in cattle and 61.9% in sheep. Infection was significantly higher in animals raised in private households than in those from collective farms. The frequency of infection increased with age in both species. In cattle and in sheep, infection of both the liver and lungs was the most common, while infection in the lungs only was much less frequent. Farm type appears to be an important factor in CE infection in Moldova, due to the extensive farming and the home-slaughtering undertaken in the majority private sector, despite a high prevalence of CE also recorded in the public sector. The low fertility of cysts in cattle (1.1%) compared to sheep (47.6%) confirmed the maintenance of E. granulosussensu stricto in a dog–sheep life cycle which excludes cattle. Further studies are needed to obtain a complete overview of the parasite's epidemiology in its intermediate and definitive hosts, in order to implement control and preventive measures, with specific attention given to farms in the private sector.

The paper contains descriptions of two new species of the genera Pterygorhabditis Timm, 1957 and Aspidonema (Sachs, 1949) Andrássy, 1958 belonging to the families Pterygorhabditidae Goodey 1963 and Bunonematidae Micoletzky 1922, respectively. Species were procured from fixed samples, collected earlier from aquatic habitats. Pterygorhabditis punctata n. sp. is characterized by a cuticle with flattened hexagonal blocks arranged in eight longitudinal rows in both sexes; each metastegostomal plate with a minute denticle, and males with long, slender, fused spicules and nine pairs of post-cloacal, prominently setose genital papillae. Aspidonema formosa n. sp. is the first report of the genus from India. The species is characterized by the right side provided with 35–48 pairs of warts flanking a row of smooth membranous shields and surrounded by a well-developed network and an anisomorphic metastegostom without discernible armature. Species are compared with other congeners, together with the diagnoses of amended genera, and keys to the identification of species are provided.

Conventional identification of Paragonimus species and their natural definitive hosts is based on the morphological features of adult parasites isolated from the lungs of wild mammalian hosts. However, wild animals are protected by strict regulations and sampling is not always possible. Recently, molecular techniques have been developed to identify the internal transcribed spacer (ITS) sequences of Paragonimus eggs in faeces/sputum of human patients. Also, mammalian hosts can be identified using the D-loop sequence of mitochondrial DNA in faecal samples. In this study, we used molecular techniques on faeces from wild animals collected in Da Krong Nature Reserve, Quang Tri province, central Vietnam, where Paragonimus metacercariae are highly prevalent in mountain crabs, to identify Paragonimus species and their natural definitive hosts. The results indicated that wild cats, Prionailurus bengalensis, were infected with at least three different Paragonimus species, P. westermani, P. skrjabini and P. heterotremus. Because all of these species can infect humans in Asian countries, human paragonimiasis should be considered in this area.

The microscaphidiid Hexangium sigani Goto & Ozaki, 1929 was found in the intestine of Siganus rivulatus, a siganid fish permanently resident in a lagoon within the mangrove swamps on the Egyptian coast of the Gulf of Aqaba. Intra-molluscan stages of this trematode (mother sporocysts, rediae and cercariae) were found in the gonads and digestive gland of Nassarius pullus (Gastropoda: Nassariidae), a common snail in the same lagoon. Consequently, the life cycle of H. sigani was elucidated under natural conditions: eggs are directly ingested by the snail; mother sporocysts and rediae reach maturity 5–7 and 16–17 weeks post-infection; rediae contain 18–26 developing cercariae; fully developed cercariae are monostome, without penetration glands, emerge from the snail during the night 18–19 weeks post-infection and rapidly encyst on aquatic vegetation (there is no second intermediate host); encysted metacercariae are not progenetic; 2-day-old metacercariae encysted on filamentous algae fed to S. rivulatus developed into fully mature worms 5–6 weeks post-infection. The cycle was completed in about 24 weeks. The intra-molluscan stages are very similar to those of Dictyangium chelydrae Stunkard, 1943, the only described intra-molluscan stages of any microscaphidiid. However, they are also similar to those of the family Mesometridae. The present study of H. sigani describes the first complete microscaphidiid life cycle, and implicitly supports the phylogenetic relationship of this family with the Mesometridae inferred from molecular phylogenetic studies.

Hymenolepis diminuta is a natural parasite of the common brown rat Rattus norvegicus, and provides a convenient model system for the assessment of the anthelmintic activity of novel drugs against cestodes. The experiments described in this paper indicate that treatment of rats infected with H. diminuta with a supernatant extract of papaya latex, containing a mixture of four cysteine proteinases, was moderately efficacious, resulting in a significant, but relatively small, reduction in worm burden and biomass. However, faecal egg output was not affected by treatment. In our experiments these effects were only partially dose-dependent, although specific inhibition by E-64 confirmed the role of cysteine proteinases as the active principles in papaya latex affecting worm growth but not statistically reducing worm burden. Data collected for a further 7 days after treatment indicated that the effects of papaya latex supernatant on worm loss and on worm growth were not enhanced. Our findings provide a starting point for further refinement in formulation and delivery, or assessment of alternative natural plant-derived cysteine proteinases in efforts to develop these naturally occurring enzymes into broad-spectrum anthelmintics, with efficacy against cestodes as well as nematodes.