The percentage composition and spatial distribution of embryogenic stages in the uteri of female Dirofilaria immitis were examined at various times after treatment with a microfilaricidal dose of ivermectin and compared to nontreated parasites. Worms sampled 42 days post-treatment (PT) exhibited an increased proportion of stretched microfilariae in the distal portion of the uterus. A decreased proportion of developed embryos was noted in the mid body region of worms sampled 42 days PT, and these forms were completely absent from the proximal area of the uterus. Relative numbers and spatial distribution of other stages remained virtually identical to controls. Radical changes in the composition and spatial distribution of embryogenic forms were noted in the uteri of a single worm sampled 80 days PT. Unlike nontreated parasites and worms sampled 42 days PT, stretched crofilariae constituted the predominant form in the distal uterus of this worm, and these stages were found in decreasing numbers throughout the proximal segments. Also, the intermediate embryogenic stages were either rare or absent.

In an attempt to develop a non-pathogenic procedure for immunising baboons against S. mansoni, groups of five baboons were exposed to three doses of 5000 6 Kr-irradiated S. mansoni cercariae or to similar numbers of normal S. rodhaini cercariae and challenged at week 15 with 500 normal S. mansoni cercariae. Faecal egg counts, worm and tissue egg counts, and histopathological examination, showed that neither of the immunising schedules had produced significant protection. In the second experiment baboons were injected by the intramuscular route with 31000 schistosomula of S. mansoni in three doses and the irradiation dose was reduced to near the minimum required for worm sterilisation (2·1–2·4 Kr). Challenge with 3500 normal cercariae of S. mansoni 21 weeks after the first immunising dose again showed no significant protection, although reductions of 20–30% were found, in egg and worm counts resulting from the challenge. These results indicate that it may be difficult to develop an effective live vaccine for S. mansoni unless the antigenicity of the immunising larvae can be greatly increased.

The life cycle of Gnathostoma nipponicum was examined by field survey and by experimental infection of animals with the larvae. Naturally infected larval G. nipponicum were found in loaches, catfish, and snakes. Experimentally, loaches, killifishes, frogs, salamanders, mice, and rats were successfully infected with the early third-stage larvae of G. nipponicum obtained from copepods (the first intermediate host), whereas snakes, quails, and weasels were not. Frogs, snakes, quails, and rats were experimentally infected with the advanced third-stage larvae (AdL3) from loaches. These results reveal that some species of fishes, amphibians and mammals can act as the second intermediate host and that some species of reptiles, birds and mammals can act as a paratenic host. The life cycle was completed in weasels, the definitive host, which were infected with AdL3 from loaches and started to evacuate eggs of G. nipponicum in faeces on days 65–90 postinfection.

Two experiments are described in which antibodies against A. suum were detected in the circulation of infected pigs by means of the conglutinating complement absorption test. The pattern and nature of the antibody response was studied. In 21 out of 24 cases the sera antibody titres rose after test doses of infective eggs were given, and on 18 of these occasions a rise in titre was observed within seven days. Following infection two peaks of antibody were detected. At three to four weeks the antibody content of the serum reached its highest concentration, and a further rise was apparent between the 37th and 56th days.

The phenomenon of “self-cure” was demonstrated following reinfection. This was manifested by a depression of the egg count and the elimination of Ascaris worms from the intestine, with a concomitant rise in the antibody content of the serum.

In three out of five pigs which were initially infected, the infection became patent between the 51st and 58th days. On only one occasion out of thirteen were any superimposed larvae able to reach maturity.

Pigs which had been previously infected exhibited resistance to a challenge dose. This was shown by (1) the absence of clinical signs, (2) a resistance to larval migration, and (3) an inhibition of larval growth. In this demonstration of an active acquired immunity to A. suum infection in pigs, a correlation between resistance and high sera titres was observed.

Entomopathogenic nematodes (EPN) are lethal parasites of insects, used as biocontrol agents. The objectives of this work were to survey the presence of EPN in continental Portugal and to characterize the different species. Of the 791 soil samples collected throughout continental Portugal, 53 were positive for EPN. Steinernema feltiae and Heterorhabditis bacteriophora were the two most abundant species. Analysis of EPN geographical distribution revealed an association between nematode species and vegetation type. Heterorhabditis bacteriophora was mostly found in the Alentejo region while S. feltiae was present in land occupied by agriculture with natural vegetation, broadleaved forest, mixed forest and transitional woodland-shrub, agro-forestry areas, complex cultivated patterns and non-irrigated arable land. Although no clear association was found between species and soil type, S. feltiae was typically recovered from cambisols and H. bacteriophora was more abundant in lithosols. Sequencing of the internal transcribed spacer (ITS) region indicated that S. feltiae was the most abundant species, followed by H. bacteriophora. Steinernema intermedium and S. kraussei were each isolated from one site and Steinernema sp. from two sites. Phylogenetic analyses of ITS, D2D3 expansion region of the 28S rRNA gene, as well as mitochondrial cytochrome c oxidase subunit I (COXI) and cytochrome b (cytb) genes, was performed to evaluate the genetic diversity of S. feltiae and H. bacteriophora. No significant genetic diversity was found among H. bacteriophora isolates. However, COXI seems to be the best marker to study genetic diversity of S. feltiae. This survey contributes to the understanding of EPN distribution in Europe.

1. Two snail species (Physa marmorata and Drepanotrema surinamensis), guppies (Poecilia reticulata), and tadpoles (Bufo marinus) prevented in various degrees the infection of susceptible B. glabrata by miracidia of S. mansoni.

8. When the animal decoys were used in “pure” groups, the snails were more efficient in reducing the infection in B. glabrata than the guppies and the tadpoles.

3. When the animal decoys were used in “mixed” groups, the combination of P. marmorata and D. surinamensis was the most efficient group in reducing the infection in B. glabrata.

Strongyloides fuelleborni is a soil-transmitted nematode parasite of non-human primates. The worm is prevalent also in human populations in Africa and South-East Asia. In this study, we amplified and sequenced a portion of the 18S ribosomal RNA gene (rRNA) and of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of Strongyloides adult males recovered from faecal samples from long-tailed macaques (Macaca fascicularis) in Thailand and Lao PDR. The prevalence in Thailand was 31.1% (55/177) and in Lao PDR it was 62.1% (41/66), with an overall prevalence of 39.5% (96/243). All 18S rRNA sequences that we obtained (n = 96) showed 100% identity with published S. fuelleborni sequences. The 96 cox1 sequences that we obtained represented 32 new haplotypes. When included with the 17 previously known haplotypes from S. fuelleborni, the cox1 sequences fell into four clusters, which had clear geographical structure. This is the first molecular confirmation of S. fuelleborni in long-tailed macaques in Thailand and Lao PDR. Clearly, awareness needs to be raised of the zoonotic potential of S. fuelleborni. A monitoring programme should be organized, taking into account the role of reservoir hosts (i.e. monkeys) in the natural background of human strongyloidiasis caused by S. fuelleborni.

The gullet worm (Gongylonema pulchrum) has been recorded from a variety of mammals worldwide, including monkeys and humans. Due to its wide host range, it has been suggested that the worm may be transmitted locally to any mammalian host by chance. To investigate this notion, the ribosomal RNA gene (rDNA), mainly regions of the internal transcribed spacers (ITS) 1 and 2, and a cytochrome c oxidase subunit I (COI) region of mitochondrial DNA of G. pulchrum were characterized using parasites from the following hosts located in Japan: cattle, sika deer, wild boars, Japanese macaques, a feral Reeves's muntjac and captive squirrel monkeys. The rDNA nucleotide sequences of G. pulchrum were generally well conserved regardless of their host origin. However, a few insertions/deletions of nucleotides along with a few base substitutions in the ITS1 and ITS2 regions were observed in G. pulchrum from sika deer, wild boars and Japanese macaques, and those differed from G. pulchrum in cattle, the feral Reeves's muntjac and captive squirrel monkeys. The COI sequences of G. pulchrum were further divided into multiple haplotypes and two groups of haplotypes, i.e. those from a majority of sika deer, wild boars and Japanese macaques and those from cattle and zoo animals, were clearly differentiated. Our findings indicate that domestic and sylvatic transmission cycles of the gullet worm are currently present, at least in Japan.

Opecoelid species Pseudopecoelus cf. vulgaris and Anomalotrema koiae Gibson & Bray, 1984 were found in fish collected in the boreal waters of the North Pacific. Pseudopecoelus cf. vulgaris differs from Pseudopecoelus vulgaris (Manter, 1934) in terms of the egg size. This is the first record of A. koiae in the North Pacific, and the second of Pseudopecoelus cf. vulgaris. Previously, A. koiae was recorded only in North Atlantic fish. Partial sequences of 28S rDNA obtained for these two species and six other previously unsequenced representatives of the family Opecoelidae were analysed together with data from GenBank. Phylogenetic analysis supports the allocation of the six clades of opecoelids – Helicometrinae, Opecoelinae, Opistholebetinae, ‘freshwater Plagioporinae’, ‘marine Plagioporinae B’ and ‘marine Plagioporinae C’, and confirms the paraphyly of the group ‘deep-sea Plagioporinae’. Our phylogeny does not support previous hypotheses about the monophyly of opecoelines with a uroproct.

Fish parasitological research associated with fisheries and aquaculture has expanded remarkably over the past century. The application of parasites as biological tags has been one of the fields in which fish parasitology has generated new insight into fish migration and stock assessments worldwide. It is a well-established discipline whose methodological issues are regularly reviewed and updated. Therefore, no concepts or case-studies will be repeated here; instead, we summarize some of the main recent findings and achievements of this methodology. These include the extension of its use in hosts other than bony fishes; the improvements in the selection of parasite tags; the recognition of the host traits affecting the use of parasite tags; and the increasingly recognized need for integrative, multidisciplinary studies combining parasites with classical methods and modern techniques, such as otolith microchemistry and genetics. Archaeological evidence points to the existence of parasitic problems associated with aquaculture activities more than a thousand years ago. However, the main surge of research within aquaculture parasitology occurred with the impressive development of aquaculture over the past century. Protozoan and metazoan parasites, causing disease in domesticated fish in confined environments, have attracted the interest of parasitologists and, due to their economic importance, funding was made available for basic and applied research. This has resulted in a profusion of basic knowledge about parasite biology, physiology, parasite–host interactions, life cycles and biochemistry. Due to the need for effective control methods, various solutions targeting host–parasite interactions (immune responses and host finding), genetics and pharmacological aspects have been in focus.

The prevalence of Fasciola hepatica infection, in endemic countries, in patients with established cirrhosis is unknown. We hypothesized that, in endemic countries, the presence of fascioliasis may be detected in a serum pool of cirrhotic patients. Forty-four previously stored serum samples of patients with established liver cirrhosis, in the Hospital Nacional Cayetano Heredia in Lima, Peru, were collected from 1998 to 2003 and assessed for hepatitis B, C and fascioliasis antibodies (Fas2 ELISA). Hepatitis B surface antigen (HBsAg) was positive in 8.8% (n = 34), hepatitis B core antibody (anti-HBc) in 32.5% (n = 34), hepatitis C antibodies (anti-HCV) in 9.1% (n = 33), and 9.1% (n = 44) were Fas2 ELISA positive. This disease is an example of an emerging tropical infection which can be present in chronic liver diseases, requiring greater clinician awareness especially in endemic rural areas. Further clinical studies are warranted.

Haemonchus contortus is a haematophagous gastrointestinal nematode (GIN) that causes severe anaemia and even death in small ruminants, negatively impacting the economic viability of farms. Traditionally, this parasite has been controlled with chemical compounds; however, inadequate use of these types of products has favoured the emergence of anthelmintic resistance. Therefore, it is necessary to search for alternatives for GIN control. Previous studies have reported the anthelmintic activity of edible mushroom extracts against H. contortus. A recent study reported that a fraction constituted of different fatty acids and β-sitosterol isolated from the basidiomata of the edible mushroom Pleurotus djamor ECS-123 has ovicidal and larvicidal activity against H. contortus. Thus, this study aimed to assess the anthelmintic activity of the pure molecules: pentadecanoic acid, palmitic acid, β-sitosterol, stearic acid and linoleic acid. For this purpose, an egg-hatching inhibition test was carried out in which the compounds were evaluated individually and in combination at a final concentration of 20 mg mL−1. Furthermore, larval mortality was assessed using a combination of the five commercial compounds previously mentioned at different concentrations (1.25–20 mg mL−1). Palmitic acid and stearic acid, in some combinations, inhibited H. contortus egg hatching by 100%. On the other hand, in the larval mortality test, the combination of the five compounds showed dose-dependent behaviour, and 100% mortality was obtained 24 h post-incubation. Pure molecules and their combinations have anthelmintic-like activity against the eggs and larvae of H. contortus.

A survey for slug-associated nematodes in five locations of East and West Flanders in Belgium revealed the presence of one new and six known slug-parasitic nematodes, Agfa flexilis (Dujardin, 1845), Alloionema appendiculatum (Schneider, 1859), Angiostoma dentiferum (Mengert, 1953), Angiostoma limacis (Dujardin, 1845), Angiostoma norvegicum (Ross et al., 2017) and Phasmarhabditis hermaphrodita (Schneider, 1859). Angiostoma norvegicum and P. hermaphrodita are recorded for the first time in Belgium. The six known species are documented by light microscopy (LM) microphotographs and informative DNA sequences. Angiostoma gandavensis n. sp. (Angiostomatidae), discovered from arionid slugs, is described based on light microscopy, scanning electron microscopy (SEM) and molecular data. Based on analyses of D2D3 expansion segment of 28S and 18S rDNA sequences, this new species is found to be related to A. limacis, A. norvegicum, A. margaretae (Ross et al., 2011) and A. milacis (Ivanova and Wilson, 2009). The new species can be distinguished from these others based on morphological characters such as the distinctive mucronate structures at the tail tip of both sexes, presence of lateral ala, reflexed female ovaries and the number and arrangement pattern of male genital papillae.

Fifty-nine of 60 (98%), 6-month-old male golden hamsters, Mesocricetus auratus, fed 15 (group A). 50 (group B), or 200 (group C) metacercarial cysts of Echinostoma caproni (Digenea: Echinostomatidae) were infected 7–34 days postexposure. The mean number of worms recovered in groups A, B and C were 9, 10, and 50, respectively. The percentage recovery was significantly different between group A (63%) and groups B (21%) and C (23%). The intestine was divided into three equal regions (I, II, III). Worms from group A were located in segments II and III of the small intestine whereas worms from groups B and C were distributed in all three segments. The body area, ovarian and testicular areas of worms from group A were greatest, followed in decreasing order by body and gonadal areas of worms from groups B and C. Echinostoma caproni eggs were found in the faeces of all the hamsters examined from groups A, B and C by days 9, 10 and 11, respectively. Physical damage occurred at the site of attachment of the echinostome. Pathological observations indicated the presence of enlarged lymphatic nodules with lymphocytes being the primary cellular infiltrate at the site of parasite attachment.

Spermatogenesis and the structure of the spermatozoon of the frog intestinal fluke, Ganeo tigrinum has been examined by electron microscopy. Each testis is covered by a tunica consisting of sustentacular cells and fibrous material. Internally the testis is lined by undifferentiated spermatogonial cells, with cytoplasm rich in free ribosomes. The arrangement of the diverse spermatogonic cell populations is similar to those studied in other digeneans. During spermatogenesis the elongation and spiralling of nuclear materials occurs synchronously in the late spermatid stage. The G. tigrinum spermatozoon appears to be biflagellate due to the presence of two filaments. Between the two filaments is an elongated nucleus; these elements fuse to form the monopartite shaft of the sperm. The spermatozoon of G. tigrinum is characterized by the presence of an unusually long nucleus that even surpasses the length of the mitochondrion. At almost half the length of the spermatozoon there is sharp rotation between first axial filament, mitochondrion and the nucleus. Both the axial filaments show 9+1 arrangement of axonemal units throughout the spermatozoon.

Using the local strains of Schistosoma bovis and Fasciola gigantica, it was shown that Sudanese zebu calves with mature primary infections of F. gigantica were highly resistant to challenge with S. bovis cercariae, and vice versa. Liver enzyme tests showed that, in both cases, the primary infections had caused some liver damage. Primary infection with irradiated S. Bovis cercariae, which did not cause significant liver damage, did not protect significantly against challenge with F. gigantica.

1. The anatomy of the genitalia of Gigantocotyle bathycotylc is described.

2. An account is given of gametogenesis, egg-shell formation, and the first two cleavage divisions.

3. The chromosome number is given as n = 6, 2n = 12.

A retrospective study was undertaken on 70 French populations of Lymnaea truncatula experimentally infected with Fasciola hepatica to determine whether or not susceptibility of snails to infection influenced redial and cercarial production. Results were compared with those obtained from two control populations, known for prevalences higher than 60% when experimentally infected with F. hepatica. In the 70 other populations examined, the prevalences ranged from 2 to 75%. In 55 of these populations, where the prevalence was more than 20%, a high proportion (50.1–56.8%) of snails died after cercarial shedding, whereas in the other groups (non-shedding snails with the most differentiated larvae being free cercariae, rediae containing cercariae, immature rediae, or sporocysts, respectively), snail death was significantly less. In 11 populations, where the prevalence values were 5–19%, only 14% of snails died after cercarial shedding, whereas snails with free cercariae, rediae with cercariae, or immature rediae showed significant increases in snail mortality. In the remaining four snail populations, with prevalences of less than 5%, the most differentiated larval forms were only immature rediae and/or sporocysts. Overall, the number of rediae containing cercariae significantly decreased with decreasing prevalence values. The low prevalence of experimental infection in several populations of snails might be explained by the occurrence of natural infections with miracidia originating from a mammalian host other than cattle, and/or by genetic variability in the susceptibility of snails to infection.

Samples of Echinococcus granulosus from seven pigs from Mexico were compared with isolates of the parasite from pigs in Poland and representative strains and species of Echinococcus. Isolates from pigs in Mexico were found to be genetically identical to E. granulosus from Polish pigs and distinct from other major genotypes by sequencing part of the mitochondrial cytochrome c oxidase I (COI) mtDNA locus, restriction fragment length polymorphism (RFLP) of the polymerase chain reaction (PCR) amplified rDNA internal transcribed spacer (ITS) 1 using five different enzymes, and random amplified polymorphic DNA (RAPD) analysis. These results were complemented by data on hook morphology and together strengthen the view that Echinococcus maintained in a cycle involving pigs and dogs is a distinct strain that is conserved genetically in different geographical areas. The present study supports the close relationship of the cervid, camel and pig strains and raises the question of their taxonomic status.

Helminths use several strategies to evade and/or modify the host immune response, including suppression or inactivation of the host antigen-specific response. Several helminth immunomodulatory molecules have been identified. Our studies have focused on immunosuppression induced by the roundworm Ascaris suum and an A. suum-derived protein named protein 1 from A. suum (PAS-1). Here we assessed whether PAS-1 is an excretory/secretory (E/S) protein and whether it can suppress lipopolysaccharide-induced inflammation. Larvae from infective eggs were cultured in unsupplemented Dulbecco's modified Eagle medium (DMEM) for 2 weeks. PAS-1 was then measured in the culture supernatants and in adult A. suum body fluid at different time points by enzyme-linked immunosorbent assay (ELISA) with the monoclonal antibody MAIP-1. Secreted PAS-1 was detected in both larval culture supernatant and adult body fluid. It suppressed lipopolysaccharide (LPS)-induced leucocyte migration and pro-inflammatory cytokine production, and stimulated interleukin (IL)-10 secretion, indicating that larval and adult secreted PAS-1 suppresses inflammation in this model. Moreover, the anti-inflammatory activity of PAS-1 was abolished by treatment with MAIP-1, a PAS-1-specific monoclonal antibody, confirming the crucial role of PAS-1 in suppressing LPS-induced inflammation. These findings demonstrate that PAS-1 is an E/S protein with anti-inflammatory properties likely to be attributable to IL-10 production.