A survey of the helminths of Scottish hill sheep, made by collecting over seven hundred viscera from sheep which died from disease or accidents on over eighty farms, has shown that worms are the direct or indirect cause of the death of many sheep, and of loss in condition of many more.

Infestations of H. contortus increase in incidence and severity in the late spring, but the majority of hill sheep are not infested with it and it is not a serious problem unless lack of herding, bad weather, etc. harm the sheep.

Ostertagia spp. are often the most numerous species found in Scottish hill sheep; their numbers increase considerably for several weeks in the spring and to a less extent and for a shorter time in the autumn. Any prophylactic dosing programmes for lambs, hoggs or adult sheep must include Ostertagia spp. in the species against which they are directed.

The numbers of T. axei increase in Scottish hill sheep during the winter and for some weeks from March onwards contribute to the pathogenic effect of clinical and subclinical helminthiasis of sheep.

The influence of temperature and ultra-violet radiation on the degree of activity, survival and infectivity of schistosome miracidia is profound. Miracidia of Schistosoma mansoni and S. haematobium were affected equally. Only miracidia classified as “active” or “slow” were capable of penetration, a capacity they retained for about 17 hours at 19°C. Miracidia that were “lethargic” as a result of low temperature, old age or ultra-violet radiation lost their infective capacity. The conclusion, however, is that neither the temperatures encountered in the field nor the solar ultra-violet radiation penetrating turbid waters are likely to be harmful to miracidia and thus have no effect on the level of transmission.

Stray cats live in high-density colonies in urban areas and pose a health hazard to household cats and humans. In Portugal, information on the parasitic fauna of stray cats is limited and relies mostly on results from faecal analysis. The present survey aimed to determine the prevalence, diversity and intensity of parasites in stray cats from the urban area of Lisbon by means of parasitological necropsy. Internal organs were collected from 162 cats captured in different areas of the city and systematically subjected to parasitological dissection. Helminths were identified by macro- and microscopic examination and protozoa by faecal floatation and sedimentation techniques. The overall prevalence of parasites was 90.7% (95% confidence interval (CI): 85.3–94.6%). A total of 12 parasite species was recorded: Cystoisospora felis (14.2%), Cystoisospora rivolta (46.3%), Sarcocystis sp. (1.2%), Ancylostoma tubaeforme (19.1%), Toxocara cati (38.3%), Ollulanus tricuspis (30.9%), Aelurostrongylus abstrusus (12.4%), Eucoleus aerophilus (0.6%), Taenia taeniaeformis (3.1%), Dipylidium caninum (53.1%), Joyeuxiella pasqualei (15.4%) and Diplopylidium nölleri (3.7%). Overall mean species richness was 2.36 ±  1.52. Helminth mean intensity was highest for O. tricuspis (285.8), followed by D. caninum (42.4), J. pasqualei (14.4), A. tubaeforme (8.1) and T. cati (5.9). The prevalence and variety of parasites found in our sampling are substantially higher than the numbers previously reported in Portugal. Some of the parasites, including T. cati and A. tubaeforme, are zoonotic, which emphasizes the need for parasite control strategies based on demographic containment of stray cat populations in urban areas to promote public health protection.

Transmission of the fox tapeworm Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, is known to depend on various environmental factors which are subject to human influence. Epidemiological data suggest that in most endemic regions anthropogenic landscape changes (e.g. deforestation and agricultural practices) have led to more favourable conditions for the parasite's animal hosts, especially arvicolid rodents, thereby increasing the risk for parasite transmission and human disease. Examples are the conversion of forests or crop fields into meadows and pastures in Europe, China and North America, and overgrazing of natural grassland in central Asia. Other anthropogenic factors include interference with host population densities by wildlife disease control, changing hunting pressure and provision of new habitats, e.g. in urban areas. Domestic dogs may, under certain conditions, get involved in the otherwise largely wildlife-based transmission, and thereby greatly increase the infection pressure to humans. The introduction of neozootic host species may increase transmission, or even initiate the parasite's life-cycle in previously non-endemic regions. Lastly, the parasite itself may be accidentally introduced into non-endemic areas, if suitable host populations are present (e.g. in northern Japan).

The activity, infectivity and fat content of ageing infective larvae of Ancylostoma caninum were investigated at regular intervals.

The reduction in activity and fat content was found to occur at a similar rate.

The relationship between the exposure of organisms to chemicals and subsequent alterations in various biochemical processes (commonly referred to as biomarkers) is of growing importance in environmental and ecotoxicological research. However, parasites which also affect the physiological homeostasis of their hosts, and thus may alter biomarker reactions, are usually ignored in environmental research. To address this deficit, we have used the host–parasite system Gammarus roeseli naturally infected with cystacanths of the acanthocephalan Polymorphus minutus to investigate whether infection of gammarids with parasites alters their heat shock protein response following exposure to palladium (Pd). After 24 days of metal exposure relative levels of heat shock protein hsp70 were analysed in the tissues of parasites and intermediate hosts. Simultaneously, the metal accumulation in gammarids and parasites was determined. As none of the infected gammarids showed hsp70 levels at the end of the Pd exposure (either exposed or not), infected and unparasitized G. roeseli were exposed to heat. Again, only uninfected gammarids showed a temperature-dependent increase in hsp70 levels. Interestingly, although the intermediate hosts showed no hsp70 response, exposure to Pd and heat results in increasing hsp70 in the parasites within in the haemocoel of G. roeseli. Heat experiments with isolated cystacanths also showed increasing hsp70 levels in P. minutus with temperature. Concerning uninfected G. roeseli, exposure to Pd and heat causes a hsp70 response. Pd concentrations were found to be higher in the larval parasites than in the gammarids. This result clearly contradicts previous results, as high metal accumulation was so far only described from adult acanthocephalans. Our findings provide experimental evidence that parasites alter the biomarker responses of their host and that the infection status of test animals is extremely important for ecotoxicological studies.

The Paragonimus ohirai group, named after P. ohirai Miyazaki, 1939, consists of three nominal species. Paragonimus iloktsuenensis Chen, 1940 and P. sadoensis Miyazaki et al., 1968, the other members of the group, were proposed primarily because of perceived differences in metacercarial morphology and/or host preferences. It has long been recognized that adults of the three were virtually indistinguishable. With the application of genetic techniques, it has become clear that the three forms can exchange genes freely, and that differences in metacercarial morphology constitute a polymorphism probably due to a single gene inherited in Mendelian fashion. Here, additional genetic data (DNA sequences from the second internal transcribed spacer of the nuclear ribosomal gene cluster and from the mitochondrial cytochrome c oxidase subunit I gene) are presented in support of the synonymy.

Anisakis third stage larvae utilize a variety of fish as intermediate hosts. Uncooked fish are rendered safe for human consumption by freezing. Larvae freeze by inoculative freezing from the surrounding medium but can survive freezing at temperatures down to -10°C. This ability may be aided by the production of trehalose, which can act as a cryoprotectant, but does not involve recrystallization inhibition. Monitoring of fish freezing in commercial blast freezers and under conditions which simulate those of a domestic freezer, indicate that it can take a long time for all parts of the fish to reach a temperature that will kill the larvae. This, and the moderate freezing tolerance of larvae, emphasizes the need for fish to be frozen at a low enough temperature and for a sufficient time to ensure that fish are safe for consumption.

Experimental studies in mice have shown that with single sex female infections of S. mattheei there is a slow maturation of the worms with evidence of incomplete parthenogenesis; at 9 weeks no eggs were produced but at 17 weeks there was an average of 500 eggs per mouse. These were all non viable. Under similar conditions S. mansoni females failed to produce eggs.

When the females of S. mattheei were paired with males of S. mansoni, the females reached full maturity and produced large numbers of eggs typical of their own species-many of the eggs were non viable but some contained active miracidia.It is considered that this is an example of parthenogenesis and not hybridisation. Cross specific pairings of schistosomes must occur frequently in man particularly with S. haematobium, S. mansoni and S. mattheei and this phenomenon could be of considerable clinical, epidemiological and biological significance. Parthenogenesis in mixed infections probably accounts for the large number of non-viable S. haematobium eggs seen in rectal biopsies, and it may also be important in reducing the transmission potential of schistosomes to man since cross pairing must result in the “sterilisation” of a considerable proportion of the female worms in mixed infections. This phenomenon may also explain the observed reproductive isolation of schistosome species which simultaneously infect the same host.

The examination of Strongylus edentatus and S. vulgaris revealed that these parasites ingest the hosts' blood and that haematin is the result of the digestion of haemoglobin. The amounts of blood necessary to form the quantities recorded as being present in the parasites' intestines have been calculated.

1. O. gutturosa infections are of widespread occurrence in South-East England. 58% of 1583 cervical ligaments from milk cattle slaughtered in an abattoir at Reading, Berkshire, showed the presence of adult worms. A more detailed study of 50 cattle from a small abattoir near St. Albans in Hertfordshire showed 42 (84%) infected.

2. The adult worms were found either in the connective tissue adjoining the nuchal ligament or between the spleen and rumen. There was no evidence of an increase in the parasite density with age of the cattle suggesting a strong immunity to superinfection.

3. Irrespective of the situation of the adult worms the microfilariae of O. gutturosa appear to have a directional mechanism and were always concentrated in the skin around the umbilicus. This is an adaptation to transmission by Simulium ornatum which bites preferentially in the umbilical region.

4. There were no marked pathological changes associated with the parasites and no evidence of clinical disease attributable to infection with O. gutturosa.

The relationship between parasite species diversity and organic pollution in the upper Manyame catchment, Zimbabwe, was investigated between October 2006 and January 2007. The parasite assemblage comprised 13 species in total. Species richness in the unpolluted sites was high; in the moderately polluted sites, it was low, while in the polluted sites, only one parasite species was encountered. Component community diversity, as measured by the Shannon index (H′), decreased with increase in organic pollution. The distribution and occurrence of ectoparasites (Dolops ranarum, Lamproglena clariae, Chonopeltis sp. and Macrogyrodactylus sp.) and one endoparasite (Lytocestus sp.) were limited to the unpolluted sites, demonstrating their sensitivity to organic pollution. The prevalence of the nematodes Paracamallanus cyathopharynx, Procamallanus laevionchus and Contracaecum spp. larvae decreased along the pollution gradient, showing their high sensitivity to organic pollution. The platyhelminths Diplostomum sp. and Polyonchobothrium clarias were the most tolerant and occurred at both polluted and unpolluted sites. Proteocephalus sp. and Caryophyllaeus sp. were limited to the polluted sites, probably as a result of high abundance of oligochaetes and copepods, their intermediate hosts that thrive in sewage-enriched sediments, at the downstream sites. The observed results assume that the decrease in parasite diversity can be related to increased organic pollution. Some parasites requiring complex life histories were absent along with pollution-related disappearance of their vector hosts. Further studies should address the identification of parasite life stages that are more sensitive to pollutants.

Unregulated economic growth in Latin America has resulted in environmental degradation, including the release of toxic compounds into the environment. One strategy to understand and prevent the outcomes of this harmful environmental degradation is the use of bioindicators. These are free-living or parasite species that respond to habitat alterations with changes in their numbers, physiology or chemical composition. The aim of this review was to determine whether there is evidence of a significant parasite response to environmental damage in Latin America. We collected 26 papers published between 2003 and 2015 and conducted a meta-analysis to test the null hypothesis that there is no significant overall effect of environmental insults on parasites. The meta-analysis showed a low but still significant negative mean overall effect (Hedges’ g = −0.221; 95% CI: −0.241 to −0.200; P < 0.0001). However, the magnitudes and directions of the significant effects varied widely. These results suggest that different groups of parasites have distinct responses to various environmental insults and that the groups should be separately analysed after the accumulation of a sufficient number of studies. For future studies on this topic in Latin America, we suggest: (1) using field and experimental approaches to determine the response of parasites to environmental degradation; (2) using an interdisciplinary approach, including different types of biomarkers in both parasites and individual hosts to generate long-term datasets in polluted and reference areas; (3) conducting studies on parasites as accumulation bioindicators.

We examine the extent to which adult helminths of freshwater fishes have been part of the Great American Biotic Interchange (GABI), by integrating information in published studies and new data from Panama with fish biogeography and Earth history of Middle America. The review illustrates the following: (1) the helminth fauna south of the Trans-Mexican Volcanic Belt, and especially south of the Isthmus of Tehuantepec, shows strong Neotropical affinities; (2) host–parasite associations follow principles of the ‘biogeographic core fauna’ in which host-lineage specificity is pronounced; (3) phylogenetic analysis of the widespread freshwater trematode family Allocreadiidae reveals a complex history of host-shifting and co-diversification involving mainly cyprinodontiforms and characids; (4) allocreadiids, monogeneans and spiruridan nematodes of Middle American cyprinodontiforms may provide clues to the evolutionary history of their hosts; and (5) phylogenetic analyses of cryptogonimid trematodes may reveal whether or how cichlids interacted with marine or brackish-water environments during their colonization history. The review shows that ‘interchange’ is limited and asymmetrical, but simple narratives of northward isthmian dispersal will likely prove inadequate to explain the historical biogeography of many host–parasite associations in tropical Middle America, particularly those involving poeciliids. Finally, our study highlights the urgent need for targeted survey work across Middle America, focused sampling in river drainages of Colombia and Venezuela, and deeper strategic sampling in other parts of South America, in order to develop and test robust hypotheses about fish–parasite associations in Middle America.

The South American subcontinent supports one of the world's most diverse and commercially very important ichthyofauna. In this context, the study of South American fish parasites is of increased relevance in understanding their key roles in ecosystems, regulating the abundance or density of host populations, stabilizing food webs and structuring host communities. It is hard to estimate the number of fish parasites in South America. The number of fish species studied for parasites is still low (less than 10%), although the total number of host–parasite associations (HPAs) found in the present study was 3971. Monogeneans, with 835 species (1123 HPAs, 28.5%), and trematodes, with 662 species (1127 HPAs, 30.9%), are the more diverse groups. Data gathered from the literature are useful to roughly estimate species richness of helminths from South American fish, even though there are some associated problems: the reliability of information depends on accurate species identification; the lack of knowledge about life cycles; the increasing number of discoveries of cryptic species and the geographically biased number of studies. Therefore, the closest true estimations of species diversity and distribution will rely on further studies combining both molecular and morphological approaches with ecological data such as host specificity, geographical distribution and life-cycle data. Research on biodiversity of fish parasites in South America is influenced by problems such as funding, taxonomic impediments and dispersion of research groups. Increasing collaboration, interchange and research networks in the context of globalization will enable a promising future for fish parasitology in South America.

The Failure Of the potato crop On some fields in South Lincolnshire has been noted for several years. The stunted growth of the plant, together with the wilting and yellowing of the foliage, usually associated with root trouble, were the symptoms observed, while the yield suffered greatly owing to the small size of the tubers formed. In a few instances the crop over the whole field was so poor that the yield hardly paid for the seed planted; others shewed bad patches which seemed to increase in size year after year.

Cystic echinococcosis is endemic in Iran, particularly in Ardabil Province, where it causes health and economic problems. The genetic pattern of Echinococcus granulosus has been determined in most parts of Iran, except in this area. In the present investigation, 55 larval isolates were collected from humans (11), sheep (19), goats (4) and cattle (21). For analysis of the genetic characteristics of E. granulosus isolates, DNA sequencing of mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes was applied. Fifty isolates were successfully analysed, with 92% (46) and 8% (4) identified as G1 and G3 genotypes, respectively. The sequence analyses of the isolates displayed nine characteristic profiles in cox1 sequences and eight characteristic profiles in nad1 sequences. Based on these results, the sheep strain (G1 genotype) was the most prevalent in humans, sheep, goats and cattle. The buffalo strain (G3 genotype) was not only demonstrated in sheep (1 isolate) and cattle (1 isolate), but also for the first time in two human isolates. These findings will provide information for local control of echinococcosis.

1. Excystment of the metacercariae of Fasciola hepatica by perforation of the inner cyst was witnessed, but the factors which control activation of the larva remain undetermined.

2. Excystment occurred in two instances when cysts were administered to mice by intra-peritoneal injections, active young flukes being recovered.

3. Excystment occurred when cysts were administered to one week old chicks and free flukes were recovered from the abdominal cavity in three instances, but liver lesions were not observed.

4. By means of photomicrographs an attempt has been made to demonstrate that young flukes feed primarily on hepatic cells and that they show a preference for this diet. Blood is inevitably included in the diet of young flukes, but it is claimed that these are not truly blood feeders.

5. Young flukes recovered from the liver of the mouse range in length from about 0·3 mm. at 3–4 days to 4·85 mm. at 28 days from the time cysts were administered (per os). This accords fairly well with data obtained by Sinitsin and by Schumacher in respect of flukes from rabbits and guineapigs respectively.

To demonstrate the prevalence of Toxocara spp. and Toxascarisleonina eggs in parks in Murcia city, eastern Spain, a total 644 soil samples were examined from nine parks. More than 67% of parks and 1.24% of soil samples were contamined and the mean egg density per sample was 16.7±20 eggs per 100 g of soil. Over 97% of eggs identified were viable. Only one sample was positive for Toxascaris leonina. The present findings suggest that shady conditions are important for the occurrence and viability of Toxocara spp. and Toxascarisleonina eggs in soil as there were significantly more positive samples in shaded and moist areas compared with open and dry habitats.

Five complimentary studies were undertaken with the overall aim to examine the ability of free-living stages of Haemonchus contortus to over-winter and tolerate cold stress. Two studies deal with the development and long-term survival of eggs and infective larvae of two geographically different isolates (Kenya and Sweden). Eggs and larvae were monitored in climatic chambers at temperatures that fluctuated daily between −1°C and 15°C, or at constant temperatures of 5°C and 15°C. The development from egg to larvae was dependent on temperatures over 5°C. The long time survival was favoured at lower temperatures. Furthermore, the overwintering capacity of the free-living stages of these isolates was estimated under Swedish field conditions. Two groups of lambs were experimentally infected with different isolates, and kept separated on previously ungrazed plots. In early May the following year, two parasite-naive tracer lambs were turned out on each of the plots to estimate the pick up of overwintered larvae. This experiment was replicated in central and southern Sweden. In addition, two experiments were performed in 2003 on pasture previously grazed by naturally infected sheep. One trial was on a pasture in southern Sweden grazed by a commercial flock, where extreme numbers of H. contortus were found towards the end of the grazing season 2002. The other study was on a pasture plot in central Sweden grazed by a hobby flock in 2002, where three of six lambs died due to haemonchiasis. Overwintered H. contortus was recorded on three of four experimental sites. Worm burdens were in all instances extremely low. No differences in development and survival were found between the isolates. Consequently, overwintering on pasture is of no practical significance in the transmission of H. contortus between grazing-seasons in Sweden.