Cystic echinococcosis (CE) is a neglected tropical disease, caused by metacestode (larval) form of the Echinococcus granulosus sensu lato (sl) in humans. MicroRNAs (miRNAs) are small, stable, tissue-specific RNA molecules encoded by the genome that are not translated into proteins. Circulating miRNA expression profiles vary in health and disease. The aim of this study is to determine the altered cellular pathways in CE by comparing the miRNA profiles of controls and CE patients with active or inactive cysts. Following abdominal ultrasonography (US) examination, 20 patients diagnosed with active CE (CE1, CE2, CE3a and CE3b) or inactive CE (CE4 and CE5) and three healthy controls were included in the study. The expression profiles of 372 biologically relevant human miRNAs were investigated in serum samples from CE patients and healthy controls with miScript miRNA HC PCR Array. Compared with the control group, expression of 6 miRNAs (hsa-miR-4659a-5p, hsa-miR-4518, hsa-miR-3977, hsa-miR-4692, hsa-miR-181b-3p, hsa-miR-4491) and one miRNA (hsa-miR-4687-5p) were found to be downregulated in CE patients with active and inactive cysts, respectively (p < 0.05). For downregulated miRNAs in this study, predicted targets were found to be associated mainly with cell proliferation, apoptosis, cell-cell interactions and cell cycle regulation. Further studies in this direction may elucidate the pathogenesis of human CE and the relationship between CE and other pathologies.

During a survey of plant diseases in the Central Highlands of Vietnam, a new plant-parasitic nematode, Hemicycliophora cardamomi sp. n., was discovered in the growing areas of Amomum longiligulare, a valuable medicinal plant with high economical value. The new species is characterized by a cuticular sheath loosely fitting body; a labial region continuous to the body contour bearing 3 annuli; a lateral field frequently marked by a discontinuous single line with indistinct additional short lines in some parts along the body; a modified vulval lip with an anterior lip c. 4 annuli long; and a post-vulval body tapering to a pointed tail tip with an abrupt constriction at the last third of the post-vulval body. Morphology and molecular characterizations of D2-D3 expansion segment of 28S rRNA, ITS, and COI mtDNA gene regions clearly distinguish the new species from all other 133 known species. This study also provides a newly developed web-based key for the identification of Hemicycliophora spp. in order to accelerate the identification process, to minimize the increasing error load associated with larger datasets, and to avoid any dependence on a single starting entry. This key includes both an existing Bray–Curtis similarity measure and a newly developed similarity formula.

Pallisentis (Pallisentis) nandai Sarkar, 1953 is a freshwater fish parasite restricted to the Indian subcontinent in the Ganga River and its tributaries. It was described from the leaffish, Nandus nandus (Hamilton) from the Ganga River delta at Calcutta. We recovered variant specimens from the same host species from the Ganga near its headwaters at Bijnor about 1500 km away. Our specimens were clearly identifiable as P. nandai but varied considerably from those in the original description, especially in the size of proboscis hooks, receptacle and lemnisci. The original description was incomplete (missing line drawings of female trunk and reproductive system, male trunk, complete proboscis, hooks and hook roots) and inaccurate (proboscis, hooks, receptacle wall), and some measurements were lumped together for both sexes. We provide a complete description and include new morphological information including the first description of para-receptacle structure in the genus Pallisentis Van Cleave, 1928, scanning electron microscopy and microscope images, molecular analysis, and energy dispersive X-ray analysis (EDXA) of hooks and spines of our specimens for the first time. Additional details of proboscis hook roots, trunk spines, micropores and micropore distribution are described. The unique metal composition of hooks (EDXA) demonstrated a considerably high but variable level of sulphur and negligible level of calcium in collar and trunk spines and hook tips, but a higher level of sulphur and calcium at the hook basal arch than at the hook tip and edge. A comparison with the EDXA pattern of another species of Pallisentis, P. İndica Mital & Lal, 1976, were considerably different. The phylogenetic position of P. nandai within Eoacanthocephala was generated to assess the molecular characterization based on 18S and ITS1-5.8S-ITS2 ribosomal DNA sequences. Maximum likelihood and Bayesian inference analyses placed P. nandai in a clade with other Pallisentis species under the family Quadrigyridae. This is the first report based on molecular evidence for P. nandai.

Donkeys have been used as working animals for transport and farm activities worldwide. Recently, in European countries, there has been an increasing interest in donkeys due to their use as pets, onotherapy or milk production. During 2014–2016, a countrywide survey was conducted to determine prevalence and risk factors of principal helminth infections in 1775 donkeys in 77 Italian farms. A questionnaire on management and parasite control practices was filled out for each farm. Faecal samples were examined using a modified McMaster technique, a centrifugation/flotation method and a sedimentation technique. Pooled coprocultures were performed for differentiation of strongylid eggs. Strongyles were the most common parasites detected (84.9%), followed by Dictyocaulus arnfieldi (6.9%), Oxyuris equi (5.8%), Parascaris spp. (3.6%), Anoplocephala spp. (1.0%), Strongyloides westeri (0.3%). Coprocultures revealed an omnipresence of cyathostomins (100%), followed by Strongylus vulgaris (31.0%), Poteriostomum spp. (25.0%), Triodontophorus spp. (9.0%), Strongylus edentatus (7.0%), Strongylus equinus (5.0%). Logistic regression analysis identified breed, co-pasture with horses, living area, herd size and number of treatments as significantly associated with strongyles. Sex, age, living area and herd size were significantly associated with Parascaris spp. Dictyocaulus arnfieldi was significantly associated with sex, grass, co-pasture with horses, living area and herd size. Strongylus vulgaris was significantly associated with living area and herd size. The mean number of anthelmintic treatments/year was 1.4; most of the donkeys (71.8%) were dewormed using an ivermectin drug. It is important to design parasite programs to specifically address both D. arnfieldi and S. vulgaris in donkeys, and this is especially important if donkeys co-graze with horses.

Populations of northern bobwhites (Colinus virginianus; hereafter bobwhite) have been declining across their geographic range in North America, prompting consideration of the role parasites may play. We conducted this study to learn about the helminth fauna in South Texas, a region that supports a sustainable bobwhite population. Helminths were examined from 356 bobwhites collected during the 2014–2015 (n = 124) and 2015–2016 (n = 232) hunting seasons, when increasing trends in precipitation were observed in comparison with the previous two years. Ten helminth species were found, consisting of 14,127 individuals. Of these, all are heteroxenous parasites and three are pathogenic (Dispharynx nasuta, Tetrameres pattersoni and Oxyspirura petrowi). Aulonocephalus pennula numerically dominated the component community (81% prevalence, 99% of the total helminths found), whereas each of the remaining species occurred rarely (≤9% prevalence) and contributed few individuals (≤0.4%) to the helminth community. Prevalence and abundance of A. pennula were not influenced by host age, sex or body mass, but abundance was higher during the 2014–2015 than the 2015–2016 hunting season. Our findings indicate that the helminth community in bobwhites from South Texas can vary during long-term, highly variable precipitation conditions and these communities are more similar to those found in the Rolling Plains of Texas than those found in the eastern part of the bobwhite's geographic range in the US.

Sphincterodiplostomum is a monotypic genus of diplostomid digeneans that parasitize fish-eating birds in the neotropics. The type species Sphincterodiplostomum musculosum has a unique, dorsal, tubular invagination in the opisthosoma with a muscular sphincter. Whereas larvae of S. musculosum are relatively commonly reported in Neotropical fish helminth surveys, adult specimens from birds are rarely collected. Prior to our study, no DNA sequence data for S. musculosum were available. Our molecular and morphological study of mature and immature adult Sphincterodiplostomum specimens from three species of birds and one species of crocodilian revealed the presence of at least two species of Sphincterodiplostomum in the neotropics. We provide the first molecular phylogeny of the Diplostomoidea that includes Sphincterodiplostomum. In addition, this is the first record of S. musculosum from caimans, along with the first record of fully mature adult S. musculosum from green kingfisher Chloroceryle americana. The new species of Sphincterodiplostomum (Sphincterodiplostomum joaopinhoi n. sp.) can be morphologically distinguished from S. musculosum based on the anterior extent of vitelline follicles, narrower prosoma, substantially smaller holdfast organ and structure of tegumental spines. Our data revealed 0.7% interspecific divergence in 28S and 10.6–11.7% divergence in cox1 sequences between the two Sphincterodiplostomum species.

A new species of the genus Aporcella collected from a watermelon field in Nigeria is described, including its morphological and molecular (small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA)) characterization. Aporcella femina sp. n. is distinguished by its 3.21–3.64 mm-long body, inner cuticle layer with fine but distinct transverse striation, lip region offset by deep constriction, 22–25 μm broad, odontostyle 20–26 μm, neck 661–811 μm long, pharyngeal expansion occupying 52–56% of the total neck length, female genital system didelphic–amphidelphic, uterus 191–350 μm or 1.9–3.3 mid-body diameters long, V = 52–57, tail short and convex conoid (35–48 μm, c = 72–98, c′ = 0.7–0.9) and males absent. Phylogenetic analyses based on the partial sequence of SSU and LSU (D2–D3) rDNA revealed a close relationship of A. femina sp. n. with other Aporcella species, confirming the monophyly of the genus as well as its association to a clade made of several taxa characterized by the absence of pars refringens vaginae.

Lake Teletskoye (West Siberia, Russia) is inhabited by a sympatric pair of whitefish, with each member of the pair being characterized by different feeding habits. Coregonus lavaretus pidschian (Gmelin, 1789) is a large ‘benthivorous’ form, while C. l. pravdinellus (Dulkeit, 1949) is a small ‘planktivorous’ form. Fish were collected from the end of August to the middle of September in 2017 and 2019–2020 in the north part of Lake Teletskoye. For the ‘benthivorous’ form the prevalence, intensity and abundance of T. crassus ranged from 22.4% to 51.9%, 1.9–2.8 and 0.4–1.3, respectively, whereas the same indices for the ‘planktivorous’ form ranged from 94.7% to 97.5%, 4.2–4.8 and 4.0–4.7, respectively. The level of prevalence of infection and abundance of T. crassus in muscle was relatively stable among studied years for both forms. The level of prevalence was higher in the years 2019 and 2020 than in 2017 for the ‘benthivorous’ form, whereas for the ‘planktivorous’ form this index did not change during the studied years. For the first time, a partial sequencing of the cox1 gene (593 bp) for T. crassus was sequenced. All 15 plerocercoids of T. crassus were represented by four haplotypes.

A total of 61 specimens representing five species of shag – Auckland Island shag Leucocarbo colensoi, little pied shag Microcarbo melanoleucos brevirostris, black shag Phalacrocorax carbo novaehollandiae, Otago shag Leucocarbo chalconotus and spotted shag Phalacrocorax punctatus – from the coast around Otago, South Island, New Zealand, were examined for helminths. A total of 18 helminth species was found: six nematodes (Anisakis pegreffi, Contracaecum rudolphii E, Baruscapillaria sp., Cosmocephalus jaenschi, Ingliseria cirrohamata, Desmidocercella australis), four trematodes (Apatemon sp. ‘jamiesoni’, Cardiocephaloides ovicorpus, Apophallus sp., Microphallidae gen. sp.), four cestodes (Microsomacanthus cormoranti, Microsomacanthus sp., Paradilepis urceina, Tetrabothrius sp.) and four acanthocephalans (Andracantha leucocarboi, A. sigma, Corynosoma hannae, Profilicollis novaezelandensis). Descriptions are provided for females of C. jaenschi and D. australis, which were previously undescribed. The data include 20 new host records and seven new locality records. New 18S ribosomal DNA and internal transcribed spacer (ITS1 and ITS2) DNA sequences have been provided where specimen conditions permitted. These data add considerably to our sparse knowledge of helminths in New Zealand shags, and provide a baseline for observations of change in the future.

The gastropod parasitic nematode Phasmarhabditis hermaphrodita has been formulated into a successful biological control agent (Nemaslug®, strain DMG0001) used to kill slugs on farms and gardens. When applied to soil, P. hermaphrodita uses slug mucus and faeces to find potential hosts. However, there is little information on what cues other species of Phasmarhabditis (P. neopapillosa and P. californica) use to find hosts and whether there is natural variation in their ability to chemotax to host cues. Therefore, using chemotaxis assays, we exposed nine wild isolates of P. hermaphrodita, five isolates of P. neopapillosa and three isolates of P. californica to mucus from the pestiferous slug host Deroceras invadens, as well as 1% and 5% hyaluronic acid – a component of slug mucus that is highly attractive to these nematodes. We found P. hermaphrodita (DMG0010) and P. californica (DMG0018) responded significantly more to D. invadens mucus and 1% hyaluronic acid than other strains. Also, P. hermaphrodita (DMG0007), P. neopapillosa (DMG0015) and P. californica (DMG0017) were superior at locating 5% hyaluronic acid compared to other isolates of the same genera. Ultimately, there is natural variation in chemoattraction in Phasmarhabditis nematodes, with some strains responding significantly better to host cues than others.

Probiotics have been shown to reduce the intensity of Toxocara canis infection in mice. However, larval transmission of this nematode also occurs via transplacental and transmammary routes. Thus, the aim of this study was to evaluate the effect of the Saccharomyces boulardii probiotic on the vertical transmission of T. canis in Swiss mice. The mice received 107S. boulardii colony-forming units per gram of food. The supplementation began 15 days before mating and was maintained throughout pregnancy and lactation. The animals were inoculated with 300 T. canis embryonated eggs on the 14th day of pregnancy. The presence of larvae was examined in the organs of the females and their offspring. The examined organs included the following: brain, liver, lungs, heart, kidneys, spleen, eye, skeletal muscle (carcass) and mammary glands of lactating females. There was a 42% (P = 0.041) reduction in the number of larvae transmitted to offspring in the group that received probiotic-supplemented food (GI). Additionally, there was a 50% reduction (P = 0.023) in the number of larvae found in the brains of lactating offspring in the GI group. These results reveal the potential of S. boulardii probiotic use as an auxiliary method of controlling visceral toxocariasis.

The northern section of the Caspian Sea and lower reaches of the Zhaiyk (Ural) River is an important fishery for Kazakhstan. In the present study, a total of 1597 individuals of ten fish species were analysed. The fish were caught over three years, from 2018 to 2020. For each species studied – Abramis brama, Alosa saposchnikowii, Atherina boyeri caspia, Carassius gibelio, Chelon auratus, Cyprinus carpio, Leuciscus aspius, Rutilus caspius, Sander marinus and Sander volgensis – between 100 and 200 individuals were examined. A series of generalized linear models (GLMs) were used to examine the association between individual parasite intensity of infection and the Fulton index, age, year the fish was captured, where the fish was captured (northern Caspian or Zhaiyk River) and sex. For each GLM, the best-fitting probability distribution was used –either Poisson, zero-inflated Poisson, negative binomial or zero-inflated negative binomial. For some fish/parasite species, an increased Fulton index was associated with higher intensities of parasite infection, whilst, for others, the Fulton index decreased with the intensity of parasite infection. This was also true of age-related intensity of infection, with some parasites having an increased intensity of infection with age whilst others had a decreased intensity of infection with age. There was also some evidence of variation in intensity of parasite infection between different years when the fish were caught. For some species of fish that are endemic to both the fresh waters of the Zhaiyk River and the low-saline waters of the northern Caspian, there were variations in intensity of parasite infection between the two environments. The best-fitting probability distribution also gave some information about the dynamics of infection. No fish species had a Poisson distribution of parasites, which is consistent with an entirely random infection process, with all fish being potentially exposed. For some parasites, the distribution was a zero-inflated Poisson, which is consistent with either the fish being exposed to parasite infection or not; and, if exposed, infection was a random process. Other parasites had a negative binomial distribution, consistent with the entire fish population being exposed, but the infection process was clumped or there were variations in the susceptibility of infection between fish. Finally, some of the parasites had a zero-inflated negative binomial distribution, which can be interpreted as part of the fish population not being exposed and the remainder of the population being exposed to a clumped or aggregated infection process and/or a variation in individual susceptibility to infection.

Lungworms can exert a negative impact on wild ruminant fitness; for this reason, the diagnosis of the associated diseases is an important prevention measure. The Baerman–Wetzel technique is the most usual method for the diagnosis of bronchopulmonary nematodes and is based on the active migration and movement of their first-stage larvae. Pulmonary tissue samples are frequently used for the post-mortem diagnosis of these parasites, but this kind of sample is not always available and easy to obtain. Faecal samples represent a more accessible choice for parasite monitoring. This work aimed to evaluate the agreement between the results obtained by the Baermann–Wetzel technique when samples of lung parenchyma or faeces from wild ruminants are used. A good level of agreement as well as a similar sensitivity between the two types of sample were observed, validating the use of faecal samples as a less invasive and cost-effective alternative for the monitoring of lungworm in wild ruminant populations.

A survey on Anisakis simplex (sensu stricto (s.s.)) from blue whiting, Micromesistius poutassou, in the north-eastern Atlantic Ocean revealed the occurrence of high infection levels of third larval stages in visceral organs and flesh. Larvae were genetically identified with a multilocus approach as A. simplex (s.s.). Histochemical, immunohistochemical and ultrastructural observations were conducted on 30 M. poutassou specimens. Gonads, pyloric caeca and flesh harboured encapsulated larvae of A. simplex (s.s.) but no intense host reaction was encountered around the parasite in the above organs. In the liver, the most infected organ, the larvae co-occurred with the coccidian Goussia sp. Within the granuloma around the A. simplex (s.s.) larvae, two concentric layers were recognized, an inner mostly comprising electron-dense epithelioid cells and an outer layer made of less electron-dense epithelioid cells. Macrophages and macrophage aggregates (MAs) were abundant out of the granulomas, scattered in parenchyma, and inside the MAs, the presence of engulfed Goussia sp. was frequent. In liver tissue co-infected with Goussia sp. and A. simplex (s.s.), hepatocytes showed cytoplasmic rarefaction and acute cell swelling. Results suggest that the host-induced encapsulation of A. simplex (s.s.) larvae is a strategic compromise to minimize collateral tissue damage around the larval infection sites, to facilitate the survival of both parasite and host.

The legume pod-borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae) (LPB), is an important insect pest of pigeon pea. Chemical pesticides are generally employed to manage this pest, but because of the soil residue issues and other environmental hazards associated with their use, biopesticides are also in demand. Another benign alternative is to use entomopathogenic nematodes (EPNs) to manage this vital pest. In the present study, the infectivity of ten native EPNs was evaluated against LPB by assessing their penetration and production in the LPB. The effectiveness of the promising EPNs against second-, third- and fourth-instar LPB larvae was also studied. Heterorhabditis sp. (Indian Agricultural Research Institute-Entomopathogenic Nematodes Rashid Pervez (IARI-EPN RP) 06) and Oscheius sp. (IARI-EPN RP 08) were found to be most pathogenic to LPB, resulting in about 100% mortality within 72 h, followed by Steinernema sp. (IARI-EPN RP 03 and 09). Oscheius sp. (IARI-EPN RP 04) was found to be the least pathogenic to LPB larva with 67% mortality. Maximum penetration was exhibited by Heterorhabditis sp. (IARI-EPN RP 06) followed by Oscheius sp. (IARI-EPN RP 08), whereas the lowest rate of penetration was exhibited by Oscheius sp. (IARI-EPN RP 01). The highest rate of production was observed with Oscheius sp. (IARI-EPN RP 08), followed by Oscheius sp. (IARI-EPN RP 04 and 10). Among the tested instars of the LPB larvae, second-instar larvae were more susceptible to EPNs, followed by third- and fourth-instar larvae. The results indicate that Heterorhabditis sp. (IARI-EPN RP 06) and Oscheius sp. (IARI-EPN RP 08) have a good potential to the manage LPB.

The mallard Anas platyrhynchos is the most abundant water bird species in Austria, but there is no record of its helminth community. Therefore, this work aimed to close that gap by recording and analysing the parasite community of a large number of birds from Austria for the first time. A total of 60 specimens shot by hunters in autumn were examined for intestinal parasites. The following taxa were recovered (prevalence given in parentheses): Cestoda: Diorchis sp. (31.7%) and Fimbriarioides intermedia (1.7%); Acanthocephala: Filicollis anatis (5%), Polymorphus minutus (30%) and one cystacanth unidentified (1.7%); Trematoda: Apatemon gracilis (3.3%), Echinostoma grandis (6.7%), Echinostoma revolutum (6.7%) and Notocotylus attenuatus (23.3%); Nematoda: Porrocaecum crassum (1.7%) and one not identified (1.7%). The frequency distribution of parasites showed a typical pattern in which 39 birds (65%) were either not parasitized or were harbouring up to five worms, whereas more intense infestations occurred in a lesser number of hosts. Compared to other studies from central and eastern Europe, an extremely depauperate helminth community, particularly of the cestodes and nematodes, was found. Polymorphus minutus was observed as having highly variable morphology and, therefore, molecular genetic characterization by DNA barcoding was carried out. Species identification was confirmed by comparing data with the reference cytochrome c oxidase subunit 1 gene sequence from P. minutus available in GenBank.

The continuous use of synthetic anthelmintics against gastrointestinal nematodes (GINs) has resulted in the increased resistance, which is why alternative methods are being sought, such as the use of natural products. Plant essential oils (EOs) have been considered as potential products for the control of GINs. However, the chemical composition and, consequently, the biological activity of EOs vary in different plant cultivars. The aim of this study was to evaluate the anthelmintic activity of EOs from cultivars of Ocimum basilicum L. and that of their major constituents against Haemonchus contortus. The EOs from 16 cultivars as well the pure compound linalool, methyl chavicol, citral and eugenol were used in the assessment of the inhibition of H. contortus egg hatch. In addition, the composition of three cultivars was simulated using a combination of the two major compounds from each. The EOs from different cultivars showed mean Inhibition Concentration (IC50) varying from 0.56 to 2.22 mg/mL. The cultivar with the highest egg-hatch inhibition, Napoletano, is constituted mainly of linalool and methyl chavicol. Among the individual compounds tested, citral was the most effective (IC50 0.30 mg/mL). The best combination of compounds was obtained with 11% eugenol plus 64% linalool (IC50 0.44 mg/mL), simulating the Italian Large Leaf (Richters) cultivar. We conclude that different cultivars of O. basilicum show different anthelmintic potential, with cultivars containing linalool and methyl chavicol being the most promising; and that citral or methyl chavicol isolated should also be considered for the development of new anthelmintic formulations.

Adult trematodes of the genus Pygorchis Looss, 1899 (Trematoda: Philophthalmidae) parasitize the cloaca of birds. The genus contains three species, all of which are rarely reported and molecular phylogenetics of which have not been applied. The absence of reference DNA sequences limit studies of their indistinct larval forms. Based on the materials that were obtained from birds of the Czech origin, we performed a molecular characterization of both currently known Pygorchis spp., which are known from the Palearctic, the type species Pygorchis affixus Looss, 1899 and Pygorchis alakolensis Zhatkanbaeva, 1967, and provided morphological description of the examined P. alakolensis specimen. We found that the two species were of similar dimensions; the only difference was in the position of testes and in the extent of vitelline follicles. However, the position of testes in P. affixus was variable, and approximately 10% of examined P. affixus individuals had testes positioned obliquely. The second feature that allows differential diagnostic, the extent of vitelline follicles, was more reproducible as the vitelline follicles of P. affixus did not extend beyond the intestinal caeca, or, in exceptional cases, they extended them at only one side. In the examined P. alakolensis individual, the testes were positioned obliquely, and the vitelline follicles extended beyond the intestinal caeca. We reported P. alakolensis for the first time from Europe; previously, it was known only from Central Asian lakes and rivers. We confirmed the classification of Pygorchis into Philophtalmidae.

During a parasitological survey of fishes at Iguazu National Park, Argentina, specimens belonging to the allocreadiid genus Auriculostoma were collected from the intestine of Characidium heirmostigmata. The erection of the new species is based on a unique combination of morphological traits as well as on phylogenetic analysis. Auriculostoma guacurarii n. sp. resembles four congeneric species – Auriculostoma diagonale, Auriculostoma platense, Auriculostoma tica and Auriculostoma totonacapanensis – in having smooth and oblique testes, but can be distinguished by a combination of several morphological features, hosts association and geographic distribution. Morphologically, the new species can be distinguished from both A. diagonale and A. platense by the egg size (bigger in the first and smaller in the last); from A. tica by a shorter body length, the genital pore position and the extension of the caeca; and from A. totonacapanensis by the size of the oral and ventral sucker and the post-testicular space. Additionally, one specimen of Auriculostoma cf. stenopteri from the characid Charax stenopterus (Characiformes) from La Plata River, Argentina, was sampled and the partial 28S rRNA gene was sequenced. The phylogenetic analysis revealed that A. guacurarii n. sp. clustered with A. tica and these two as sister taxa to A. cf. stenopteri. The new species described herein is the tenth species in the genus and the first one parasitizing a member of the family Crenuchidae.

The aim of this study was to explore through cross-sectional study the variation in the prevalence of parasitic helminths in canine faeces collected from green spaces of Buenos Aires according to the human density (HD) and economic level (EL) in the surroundings. HD and EL were considered as independent variables with three categories each. Twenty public squares (one hectare of surface) were randomly selected for each existing combination of the two independent variables. Ten random samples of fresh canine faeces were obtained in each square and analysed for helminths by the sedimentation and flotation techniques. The prevalence for each of the species was analysed using generalized linear models (GLM). The prevalence was modelled with a binomial error distribution and a logit link function. Helminth eggs were detected in 45 out of the 200 (22.5%) faecal samples collected and in 18 of the 20 green spaces sampled. The species observed were Ancylostoma caninum (13% of samples), Trichuris vulpis (8%) and Toxocara canis (4.5%). The GLM indicated that the prevalence of A. caninum in the slum areas (very high HD and very low EL) was higher than that in the other areas studied. However, the HD seemed to contribute more than the EL to the variations in the prevalence of A. caninum in faecal samples. The GLM showed no differences in the prevalence of the other parasite species for the different levels of the independent variables.