Considered a secondary zoonotic disease until the mid-1990s, human fascioliasis is at present emerging or re-emerging in many countries, including increases of prevalence and intensity and geographical expansion. Research in recent years has justified the inclusion of fascioliasis in the list of important human parasitic diseases. At present, fascioliasis is a vector-borne disease presenting the widest known latitudinal, longitudinal and altitudinal distribution. Fasciola hepatica has succeeded in expanding from its European original geographical area to colonize five continents, despite theoretical restrictions related to its biology and in turn dependent upon environmental and human activities. Among the different epidemiological situations, human hypo- to hyperendemic areas, including epidemics, are noteworthy. A global analysis of the distribution of human cases shows that the expected correlation between animal and human fascioliasis only appears at a basic level. Areas presenting very high human prevalences and intensities, especially in children and females, have been recently described. In hypo- to hyperendemic areas of Central and South America, Europe, Africa and Asia, human fascioliasis presents a range of epidemiological characteristics related to a wide diversity of environments. Thus far well-known epidemiological patterns of fascioliasis may not always explain the transmission characteristics in any given area and control measures should consider the results of ecoepidemiological studies undertaken in the zones concerned.

Clonorchis sinensis, the Chinese or oriental liver fluke, is an important human parasite and is widely distributed in southern Korea, China (including Taiwan), Japan, northern Vietnam and the far eastern part of Russia. Clonorchiasis occurs in all parts of the world where there are Asian immigrants from endemic areas. The human and animal reservoir hosts (dogs, pigs, cats and rats) acquire the infection from the ingestion of raw fish containing infectious metacercariae. The first intermediate snail hosts are mainly species of Parafossarulus and Bithynia. Numerous species of freshwater fish serve as the second intermediate hosts of C. sinensis. Extensive studies of clonorchiasis during several decades in Japan, Korea, China and other countries have shown much progress in proving its morphological features including ultrastructure, biology, pathogenesis, epidemiology, clinical manifestations and chemotherapy. The present review deals with mainly current results obtained on the epidemiological, pathological and clinical aspects, as well as control measures in endemic areas. As for the complications of clonorchiasis, formation of calculi in the intrahepatic biliary passages is one of the most characteristic pathological features. It is sometimes accompanied by suppurative cholangitis, cholecystitis, cholangiohepatitis and ultimately can cause cholangiocarcinoma. Experimental results on the relationship to the occurrence of cholangiocarcinoma are presented. Clinical diagnosis by radiological findings including cholangiography, sonography and computerized tomography as well as magnetic resonance imaging for biliary or pancreatic ducts are outlined. Current studies on immunology and molecular biology of C. sinensis were introduced. Praziquantel is the drug of choice for clonorchiasis. The most effective regimen is 25 mg kg−1 three times daily (total dose, 75 mg kg−1) administered orally at 5- to 6-h intervals over a single day. Prevention and control measures are also discussed.

A method of recovering cysts from soils of not more than 10% water content is described. The method is continuous and the yield from it is only slightly lower than that from the dry flotation of soil. The yield was found to contain a slightly lower percentage of full cysts than that obtained by dry flotation but this drop was not considered sufficiently great to justify the drying of soil in large quantities. Quantities of soil in the neighbourhood of 1 cwt. can be handled continuously in a matter of two hours.

Over the past decades, various free-living animals (hosts) and their parasites have invaded recipient areas in which they had not previously occurred, thus gaining the status of aliens or exotics. In general this happened to a low extent for hundreds of years. With variable frequency, invasions have been followed by the dispersal and establishment of non-indigenous species, whether host or parasite. In the literature thus far, colonizations by both hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways. As to those factors permitting invasive success and colonization strength, various hypotheses have been put forward depending on the scientific background of respective authors and on the conspicuousness of certain invasions. Researchers who have tried to analyse characteristic developmental patterns, the speed of dispersal or the degree of genetic divergence in populations of alien species have come to different conclusions. Among parasitologists, the applied aspects of parasite invasions, such as the negative effects on economically important hosts, have long been at the centre of interest. In this contribution, invasions by hosts as well as parasites are considered comparatively, revealing many similarities and a few differences. Two helminths, the liver fluke, Fasciola hepatica, of cattle and sheep and the swimbladder nematode, Anguillicola crassus, of eels are shown to be useful as model parasites for the study of animal invasions and environmental global change. Introductions of F. hepatica have been associated with imports of cattle or other grazing animals. In various target areas, susceptible lymnaeid snails serving as intermediate hosts were either naturally present and/or were introduced from the donor continent of the parasite (Europe) and/or from other regions which were not within the original range of the parasite, partly reflecting progressive stages of a global biota change. In several introduced areas, F. hepatica co-occurs with native or exotic populations of the congeneric F. gigantica, with thus far unknown implications. Over the fluke's extended range, in addition to domestic stock animals, wild native or naturalized mammals can also serve as final hosts. Indigenous and displaced populations of F. hepatica, however, have not yet been studied comparatively from an evolutionary perspective. A. crassus, from the Far East, has invaded three continents, without the previous naturalization of its natural host Anguilla japonica, by switching to the respective indigenous eel species. Local entomostrac crustaceans serve as susceptible intermediate hosts. The novel final hosts turned out to be naive in respect to the introduced nematode with far reaching consequences for the parasite's morphology (size), abundance and pathogenicity. Comparative infection experiments with Japanese and European eels yielded many differences in the hosts' immune defence, mirroring coevolution versus an abrupt host switch associated with the introduction of the helminth. In other associations of native hosts and invasive parasites, the elevated pathogenicity of the parasite seems to result from other deficiencies such as a lack of anti-parasitic behaviour of the naïve host compared to the donor host which displays distinct behavioural patterns, keeping the abundance of the parasite low. From the small amount of available literature, it can be concluded that the adaptation of certain populations of the novel host to the alien parasite takes several decades to a century or more. Summarizing all we know about hosts and parasites as aliens, tentative patterns and principles can be figured out, but individual case studies teach us that generalizations should be avoided.

For the sensitive detection of eggs of Echinococcus multilocularis in fox faeces by PCR we have evaluated a method based on the previous concentration of helminth eggs by a combination of sequential sieving of faecal samples and flotation of the eggs in zinc chloride solution. The eggs were microscopically detected in the fractions retained in 40 and 20µm mesh sieves. DNA of the taeniid eggs retained in the 20 µm sieve was obtained after alkaline lysis and PCR was performed using E. multilocularis species-specific primers. Compared to the parasitological findings after examination of the small intestines of the foxes, the specificity of the PCR was 100% (no false-positive result with 20 foxes free of E. multilocularis) and the sensitivity was 94% (33 positive results from total 35 foxes proven to be infected with E. multilocularis). Both false-negative results were obtained with faeces from foxes harbouring immature worms. Using faecal volumes between 2 and 20 ml, no inhibition of PCR was observed as was demonstrated by the amplification of size-modified target in parallel reactions. The tests were undertaken with fresh faeces stored in 70% ethanol, but egg detection by PCR was also possible after inactivation of eggs by freezing the faeces at −80°C for one week or by incubation at +70°C for 2 h.

Triclabendazole was introduced in the early 1980s for the treatment of Fasciola hepatica infections in livestock. Due to its high activity against immature flukes, it has become established as the principal anti-fluke drug on the market. More recently, triclabendazole has been used to treat human cases of fascioliasis and is now the drug of choice for this infection, too. Resistance to triclabendazole was first reported in 1995 in a field population in Australia and, since that time, resistant populations have been identified in several countries in Europe. Parallel to the spread of resistance has been a sharp increase in the prevalence of fascioliasis, which has been attributed largely to climate changes. Consequently, farmers are faced with an alarming scenario, as none of the other fasciolicides on the market possess such high activity against the damaging immature stages of fluke. The main aim of this review is to assess current understanding of the mechanism of action of triclabendazole against the fluke and the mechanism by which the fluke has become resistant to it. The use of triclabendazole against animal and human infections is summarized and suggestions are given on ways to deal with resistance. Gaps in the knowledge of various aspects of its use are highlighted and this may serve to open up future research areas.

Triclabendazole (TCBZ) remains the drug of choice for treating infections of the liver fluke, Fasciola hepatica in livestock and has become the main drug used to treat human cases of the disease as well. Cases of resistance in livestock continue to be reported, suggesting that the problem is increasing. In order to address the problem, there is a need for better understanding of drug action. A ‘state-of-play’ review on different aspects of TCBZ activity was published by the present author in 2005. The main purpose of the current review is to assess what progress has been made in the past four years towards understanding the main aspects of drug activity, including drug pharmacokinetics and pharmacodynamics and an understanding of the mechanism(s) of resistance. Also, what advances have been made in identifying alternative compounds and using drug combinations to enhance TCBZ activity. Stemming from a number of in vivo studies, it has become evident that fluke isolates of differing sensitivity to TCBZ differ in some of their biological parameters, and information on this interesting phenomenon will be presented. An update on the use of TCBZ for human fascioliasis is also given. The review will indicate what progress has been made, but will also highlight areas that remain inadequately understood and require greater research focus.

Digenea Carus, 1863 represent a highly diverse group of parasitic platyhelminths that infect all major vertebrate groups as definitive hosts. Morphology is the cornerstone of digenean systematics, but molecular markers have been instrumental in searching for a stable classification system of the subclass and in establishing more accurate species limits. The first comprehensive molecular phylogenetic tree of Digenea published in 2003 used two nuclear rRNA genes (ssrDNA = 18S rDNA and lsrDNA = 28S rDNA) and was based on 163 taxa representing 77 nominal families, resulting in a widely accepted phylogenetic classification. The genetic library for the 28S rRNA gene has increased steadily over the last 15 years because this marker possesses a strong phylogenetic signal to resolve sister-group relationships among species and to infer phylogenetic relationships at higher levels of the taxonomic hierarchy. Here, we have updated the database of 18S and 28S rRNA genes until December 2017, we have added newly generated 28S rDNA sequences and we have reassessed phylogenetic relationships to test the current higher-level classification of digeneans (at the subordinal and subfamilial levels). The new dataset consisted of 1077 digenean taxa allocated to 106 nominal families for 28S and 419 taxa in 98 families for 18S. Overall, the results were consistent with previous higher-level classification schemes, and most superfamilies and suborders were recovered as monophyletic assemblages. With the advancement of next-generation sequencing (NGS) technologies, new phylogenetic hypotheses from complete mitochondrial genomes have been proposed, although their power to resolve deep levels of trees remains controversial. Since data from NGS methods are replacing other widely used markers for phylogenetic analyses, it is timely to reassess the phylogenetic relationships of digeneans with conventional nuclear rRNA genes, and to use the new analysis to test the performance of genomic information gathered from NGS, e.g. mitogenomes, to infer higher-level relationships of this group of parasitic platyhelminths.

COST Action 819: Entomopathogenic nematodes, supercedes Action 812: Cold active lines of insect parasitic nematodes in Agriculture and Biotechnology. It functions in the field of Agriculture and Biotechnology and began in July 1994 and will end in May, 1999. The main objective is to combine interrelated European expertise to increase the use of entomopathogenic nematodes (EPNs) in integrated pest management and to reduce the need for chemical control. Coordination of the Action is the responsibility of a management committee in accordance with a Memorandum of Understanding, which has been signed by representatives of 17 countries: Austria, Belgium, Czech Republic, Finland, France, Germany, Hungary, Ireland, Italy, The Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland and the UK. A research institute in Israel is also participating. Over 40 research institutions and 10 commercial companies participate in Action 819. The EU funding meets the costs related to coordination including the scientific secretariat, workshops, management committee and working group meetings, publications, short term scientific missions and evaluations.

By clarifying which taxonomic characters are of specific significance and by defining the intra specific limits of individual morphological variations, seventeen species of the genus Anisakis were shown to represent only three distinguishable forms, these being Anisakis simplex (Rudoiphi, 1809 det. Krabbe, 1878), A. typica (Diesing, 1860) and A. physeteris Baylis, 1923. The morphological characters in order of importance for identifying these species are the spicules, the postanal papillae, the form of the ventriculus, the position of the vulva and the form of the lips. These three species were also found to be satisfactory when discussed in geographical and ecological terms.

The four remaining species in the genus, Anisakis dussumierii (van Beneden, 1870), A. alexandri Hsü and Hoeppli, 1933, A. insignis (Diesing, 1851) and A. schupakovi Mozgovoi, 1915 are retained as species inquirendae for lack of sufficient information concerning them.

Faecal examinations for helminth eggs were performed on 1869 people from two riverside localities, Vientiane Municipality and Saravane Province, along the Mekong River, Laos. To obtain adult flukes, 42 people positive for small trematode eggs (Opisthorchis viverrini, heterophyid, or lecithodendriid eggs) were treated with a 20–30 mg kg−1 single dose of praziquantel and purged. Diarrhoeic stools were then collected from 36 people (18 in each area) and searched for helminth parasites using stereomicroscopes. Faecal examinations revealed positive rates for small trematode eggs of 53.3% and 70.8% (average 65.2%) in Vientiane and Saravane Province, respectively. Infections with O. viverrini and six species of intestinal flukes were found, namely, Haplorchis taichui, H. pumilio, H. yokogawai, Centrocestus caninus, Prosthodendrium molenkampi, and Phaneropsolus bonnei. The total number of flukes collected and the proportion of fluke species recovered were markedly different in the two localities; in Vientiane, 1041 O. viverrini (57.8 per person) and 615 others (34.2 per person), whereas in Saravane, 395 O. viverrini (21.9 per person) and 155207 others (8622.6 per person). Five people from Saravane harboured no O. viverrini but numerous heterophyid and/or lecithodendriid flukes. The results indicate that O. viverrini and several species of heterophyid and lecithodendriid flukes are endemic in these two riverside localities, and suggest that the intensity of infection and the relative proportion of fluke species vary by locality along the Mekong River basin.

A total of 21 species of Cyathostominae was found in the lumen of the large intestine of 86 mature horses of various ages and breeds killed in south-west England during 1972–1974. Cylicostephanus longibursatus, C. goldi, C. calicatus, Cyathostomum catinatum, C. coronatum and Cylicocylus nassatus were found in over 80% of the horses, while 12 of the remaining species were detected in less than 30%. Quantitative studies on 55 horses showed the adult cyathostome burdens to rise to a sharp peak (average over 400,000/horse) in April-June and a lower one in November-December. Parallel fluctuations occurred in the lumen populations of 4thstage larvae. The most numerous cyathostomes were generally those species with the highest prevalence. The five most plentiful (C. nassatus, Cyathostomum catinatum, Cylicostephanus longibursatus, C. minutus and C. goldi) comprised over 90% of the total number of adult cyathostomes recovered. The three regions of the large intestine had adult cyathostome faunas of different composition. That of the dorsal colon was dominated by C. longibursatus and C. goldi, the ventral colon by Cylicocyxlus nassatus and Cyathostomum catinatum, while the sparsely inhabited caecum accommodated several equally numerous species. Each species showed a characteristic site distribution, 11 occurring predominantly in the ventral colon, eight in the dorsal colon and two in the caecum. Seasonal changes in the site distributions of C. catinatum and Cylicocyclus nassatus and in the size of the cyathostome burdens are discussed in relation to the epidemiology of cyathostome infections.

The African schistosomes fall naturally into two main groups of sibling species, the S. haematobium complex and the S. mansonil S. rodhaini group. Morphological differentiation of the species within each group depends on small differences in the eggs but in many cases there are clear biological differences in definitive and intermediate host specificity and in parasitic site within the host, and these criteria serve to strengthen a classification based on egg morphology. Nevertheless, many authors have disputed the validity

Larval Anisakis 7·7 to 23·6mm long from euphausiids, and larvae 18·0 to 21·9mm long from a teleost fish were morphologically and morphometrically alike and fitted the description by Beverley-Burton, Nyman & Pippy (1977) of A. simplex L3. Three small larvae, 4·2 to 5·9mm long, from euphausiids resembled L3 in anterior but not in posterior morphology; their tails lacked a mucron but, in two of them, cuticular separation at the posterior extremity revealed clearly the mucron characteristic of L3 within. These small larvae are identified as L2 of A. simplex in the process of moulting to L3. Japanese reports of typical L3 from 6·9 to 32·7 mm long in euphausiids, the occurrence in teleosts of typical L3 from only 8·8 to over 30 mm long, and the present observations strongly suggest that the moult from L2 to L3 occurs in euphausiids and begins when the larvae are about 4–6 mm long. Although it appears, therefore, that only one moult occurs in the egg of A. simplex (i.e. ensheathed L2 hatches), two moults there have been reported for various terrestrial and certain aquatic ascaridoids (i.e. ensheathed L3 hatches). The morphology and homology of the lips and associated sense organs of A simplex L3 are discussed relative to that of a ‘typical’ adult ascaridoid.

A main conclusion is that euphausiids in the North-East Atlantic and northern North Sea, and perhaps universally, are major intermediate hosts of A simplex. The status as hosts of squid and teleosts harbouring L3 is discussed. An extensive literature is reviewed in relation to the present observations.

It was found that in six aged horses after treatment with 30 grammes of phenothiazine the faecal egg count fell to zero but had returned to a high level after some live or six weeks. Examination of the faeces at the time of treatment showed that many worms were eliminated. Repetition of the treatment several times produced a similar result on each occasion, but there was a tendency for the egg count not to rise so high as it was before treatment, for fewer worms to be eliminated at each treatment, and for the time before the egg count reached a high level after treatment to lengthen with each successive treatment. Many treatments had to be given over a period of some three years before the egg counts of the horses were reduced permanently to a low level. Post-mortem examination of three of the horses at this stage showed their worm burdens to be low.

Evidence is accumulating rapidly showing that temperature and other climatic variables are driving many ecological processes. At the same time, recent research has highlighted the role of parasitism in the dynamics of animal populations and the structure of animal communities. Here, the likely interactions between climate change and parasitism are discussed in the context of intertidal ecosystems. Firstly, using the soft-sediment intertidal communities of Otago Harbour, New Zealand, as a case study, parasites are shown to be ubiquitous components of intertidal communities, found in practically all major animal species in the system. With the help of specific examples from Otago Harbour, it is demonstrated that parasites can regulate host population density, influence the diversity of the entire benthic community, and affect the structure of the intertidal food web. Secondly, we document the extreme sensitivity of cercarial production in parasitic trematodes to increases in temperature, and discuss how global warming could lead to enhanced trematode infections. Thirdly, the results of a simulation model are used to argue that parasite-mediated local extinctions of intertidal animals are a likely outcome of global warming. Specifically, the model predicts that following a temperature increase of less than 4°C, populations of the amphipod Corophium volutator, a hugely abundant tube-building amphipod on the mudflats of the Danish Wadden Sea, are likely to crash repeatedly due to mortality induced by microphallid trematodes. The available evidence indicates that climate-mediated changes in local parasite abundance will have significant repercussions for intertidal ecosystems. On the bright side, the marked effects of even slight increases in temperature on cercarial production in trematodes could form the basis for monitoring programmes, with these sensitive parasites providing early warning signals of the environmental impacts of global warming.

The two geohelminths, Ascaris lumbricoides and Trichuris trichiura, infect more than a billion people worldwide but are only reported sporadically in the developed part of the world. In contrast, the closely related species A. suum and T. suis in pigs have a truly global distribution, with infected pigs found in most production systems. In areas where pigs and humans live in close proximity or where pig manure is used as fertilizer on vegetables for human consumption, there is a potential risk of cross-infections. We therefore review this relationship between Ascaris and Trichuris in the human and pig host, with special focus on recent evidence concerning the zoonotic potential of these parasites, and identify some open questions for future research.

Ecological changes in the Senegal River Basin (SRB) resulting from the construction of a barrage at Diama, Senegal on the Senegal River to prevent the intrusion of sea water into the river, and a dam at Manantali, Mali on the Bafing River to control the flow of water and to generate electricity, have been responsible for changes in the epidemiology of human schistosomiasis. The introduction of Schistosoma mansoni into the Lower and Middle Valleys of the SRB and subsequent spread of the parasite in the human population is recorded with regard to prevalence and intensity. New foci of S. haematobium are described. The reduction in salinity and change from an acidic to an alkaline environment in the water are beneficial to both the fecundity and growth of freshwater snails and transmission of the parasite. The creation of new irrigation canals and expansion of the rice fields have provided new habitats for intermediate hosts to colonize. The evidence for praziquantel resistance/tolerance by populations of S. mansoni and the possibilities of the development, production and testing of a vaccine against human schistosomiasis are discussed. Future studies will monitor the spread of human urinary and mesenteric schistosomiasis in the SRB, will evaluate further the presence of praziquantel resistance/tolerance in S. mansoni, will examine the heavily infected human population for pathological symptoms and determine the most appropriate methods to control this severe outbreak of human schistosomiasis.

In a cross-sectional study, a total of 5381 slaughtered animals, namely 928 cattle, 243 buffaloes, 3765 sheep and 445 goats were inspected macroscopically for hydatid cysts in northwest Iran, with prevalence values of 38.3%, 11.9%, 74.4% and 20%, respectively, being recorded. Prevalences were higher in females compared with males, but a significant difference (P < 0.001) was only found in sheep and cattle. Most cases which were condemned were seen in the lungs of sheep (13.4%) indicating that sheep are the most important intermediate hosts for Echinococcus granulosus in this area.

Groups of breeding ewes were slaughtered at intervals before and after lambing in March. A post-parturient rise in egg count was observed in which Ostertagia spp. were dominant but in which other species took part, in particular Haemonchus contortus, Nematodirus battus and Chabertia ovina. The important contribution made by dormant larvae of Ostertagia spp. was confirmed but it was also found that reinfection greatly increased the number of worms present while the earliest part of the rise, often beginning prior to parturition, was probably due to the increased fecundity of adult worms already present. Adults of H. contortus present in ewes after lambing were derived from the maturation of dormant larvae and it is probable that the same applied to C. ovina. The close association of the postparturient rise with lactation rather than with pregnancy or parturition was shown and two possible explanations for this were discussed.