Assessment of climatic and orographic conditions on the infection by Calicophoron daubneyi and Dicrocoelium dendriticum in grazing beef cattle (NW Spain)

Validation of deep amplicon sequencing of Dicrocoelium in small ruminants from Northern regions of Pakistan

Dicrocoelium lancet flukes cause significant production loss in ruminant livestock. Although co-infection with multiple Dicrocoelium species within a host is common, techniques for studying the composition of these complex parasite communities are lacking. The pathogenicity, epidemiology, and therapeutic susceptibility of different helminth species vary, and little is known about the interactions that take place between co-infecting species and their hosts. Here, we describe the first applicationof metabarcoding deep amplicon sequencing method to studythe Dicrocoelium species in sheep and goats. First, rDNA ITS-2 sequences of four Dicrocoelium species (Dicrocoelium dendriticum, Dicrocoelium hospes, Dicrocoelium orientalis, and Dicrocoelium chinensis) were extracted from the NCBI public database. Phylogenetic analysis revealed separate clades of Dicrocoelium species; hence, molecular differentiation between each species is possible in co-infections. Second, 202 flukes belonging to seventeen host populations (morphologically verified as belonging to the Dicrocoelium genus) were evaluated to determine the deep amplicon sequencing read threshold of an individual fluke for each of the four species. The accuracy of the method in proportional quantification of samples collected from single hosts was further assessed. Overall, 198 (98.01%) flukes were confirmed as D. dendriticum and 1.98% produced no reads. The comparison of genetic distances between rDNA ITS-2 revealed 86% to 98% identity between the Dicrocoelium species. Phylogenetic analysis demonstrated a distinct clustering of species, apart from D. orientalis and D. chinensis, which sit very close to each other in a single large clade whereas D. hospes and D. dendriticum are separated into their own clade. In conclusion each sample was identified as D. dendriticum based on the proportion of MiSeq reads and validated the presence of this group of parasites in the Gilgit Baltistan and Khyber Pakhtunkhwa provinces of Pakistan. The metabarcoding deep amplicon sequencing technology and bioinformatics pathway have several potential applications, including species interactions during co-infections, identifying the host and geographical distribution of Dicrocoelium in livestock, drug therapy response evaluation and understanding of the emergence and spread of drug resistance.

Pulmonary and Gastrointestinal Parasitic Infections in Small Ruminant Autochthonous Breeds from Centre Region of Portugal-A Cross Sectional Study

The production of small ruminant autochthonous breeds in the Centre region of Portugal is practiced in a semi-extensive husbandry system, exposing animals to parasitic infections. The main objective of this study was to estimate the prevalence of lungworm infection and identify risk factors. Fecal samples of 203 goats and 208 sheep from 30 herds were collected per rectum and subjected to the modified Baermann test. The overall prevalence of infection was 57.7%, significantly higher in goats (95.6%) than in sheep (20.7%) (p < 0.001). According to the binary logistic regression model, sheep dewormed with albendazole, mebendazole plus closantel, or ivermectin plus clorsulon presented a risk of Protostrongylidae infection 29.702, 7.426, or 8.720 times higher, respectively, than those dewormed with eprinomectin. Additionally, the presence of gastrointestinal parasites was investigated in 307 fecal samples using Mini-FLOTAC®. The overall prevalence of infection was 86.3%, also significantly higher in goats (93.2%) than in sheep (79.9%) (p < 0.001). Strongyle-type eggs were the most frequently identified, both in sheep (69.8%) and goats (87.8%), followed by Eimeria oocysts (40.3% in sheep and 68.9% in goats). Considering the high prevalence and the burden of lungworm parasitic infection, it is urgent to determine its economic impact and the repercussions in animal health in the Centre region of Portugal to establish appropriate therapeutic guidelines.

Spatial Distribution of Dicrocoelium in the Himalayan Ranges: Potential Impacts of Ecological Niches and Climatic Variables

PURPOSE

Dicrocoeliosis can be an important cause of production loss in ruminants due to the cost of liver condemnation at slaughter. The aim of the present study was to determine the prevalence of Dicrocoelium infection and to predict the ecological niches and climatic variables that support dicrocoeliosis in the Himalayan ranges of Pakistan.

METHODS AND RESULTS

Dicrocoelium was detected in 33 of 381 liver samples and 238 of 6060 blood samples taken from sheep and goat herds in the area. The prevalence of dicrocoeliosis was higher in sheep than in goats and highest in females aged more than 3 years. An environmental risk map was created to predict active zones of transmission and showed the highest probability values in central parts of the Chitral district in the northwest of Pakistan. Climatic variables of the mean monthly diurnal temperature range (Bio2), annual precipitation (Bio12), and normalised difference vegetation index (NDVI) were found to be significantly (p < 0.05) associated with the presence of Dicrocoelium infection.

CONCLUSION

Together, the findings of this study demonstrate the most suitable ecological niches and climatic variables influencing the risk of dicrocoeliosis in the Himalayan ranges of Pakistan. The methods and results could be used as a reference to inform the control of dicrocoeliosis in the region.

The effect of naturally acquired rumen fluke infection on animal health and production in dairy and beef cattle in the UK

The incidence of paramphistomosis, caused by the rumen fluke, Calicophoron daubneyi, has greatly increased within Europe in the last 15–20 years. However, the production impacts of this disease are poorly understood. This study firstly aimed to investigate the prevalence of rumen fluke in England and Northern Ireland (NI) by conducting an abattoir survey of dairy and beef cattle which also allowed the impact of rumen fluke on carcass weight, conformation and fat classification to be assessed. Secondly, an experiment aimed to assess the impact of C. daubneyi infection on diarrhea score, production loss and welfare in dairy heifers, while also evaluating the impacts of treating infected heifers with oxyclozanide. Rumen fluke prevalence was greater in NI than in England, with 53.8% (95% CI 51.9 - 55.9%) of the NI cattle carcases sampled being infected compared to 16.3% (95% CI 15.8 - 16.8%) and 17.9% (95% CI 17.4 - 18.4%) detected at the two abattoirs in England. However, there was no significant difference (P > 0.05) in the cold carcass weight between infected and non-infected cattle. Similarly, carcass conformation and fat classification were unaffected (P > 0.05) by the presence of rumen fluke. In the second experiment, daily live weight gain (DLWG), diarrhea score and welfare score were also unaffected (P > 0.05) by rumen fluke infection and by oxyclozanide treatment against rumen fluke. The farms in this experiment were managed to a high standard and animals had no intercurrent disease. Therefore, these findings suggest that on well–managed farms, production losses (growth rates) should not be compromised as a result of sub-clinical rumen fluke infection.

Molecular analysis of internal transcribed spacer 2 of Dicrocoelium dendriticum isolated from cattle, sheep, and goat in Iran

Background

Dicrocoelium dendriticum is a broadly distributed zoonotic helminth, which is mainly reported from domesticated and wild ruminants. There is little data covering the molecular features of this trematode; therefore, current study aimed to molecularly analyze D. dendriticum in livestock.

Methods

Totally, 23 samples of D. dendriticum were collected from cattle, sheep, and goat from Ilam, Lorestan, and Khuzestan, three west and south-west provinces of Iran from February to August 2018. After genomic DNA extraction, the internal transcribed spacer (ITS) 2 fragment was amplified and sequenced in samples. To investigate genetic variations through the ITS 2 fragment of obtained D. dendriticum, phylogenetic tree and network analysis were employed.

Results

All 23 samples were successfully amplified and sequenced. Phylogenetic tree showed that our samples were clearly grouped in a clade together with reference sequences. There was no grouping based on either geographical regions or hosts. Network analysis confirmed the phylogenetic findings and showed the presence of nine distinct haplotypes, while our samples together most of sequences, which were previously submitted to the GenBank, were grouped in the Hap1.

Conclusions

Our findings indicated that although ITS 2 fragment discriminate D. dendriticum, this fragment is not suitable to study intra-species genetic variations. Therefore, exploring and describing new genetic markers could be more appropriate to provide new data about the genetic distribution of this trematode.

Rumen fluke infections (Paramphistomidae) in diarrhoeal cattle in western France and association with production parameters

This study was conducted to assess the impact of rumen flukes (RFs) (Paramphistomatidae) on various production parameters of cattle in Normandy. Faecal and blood samples were taken between 1 January 2010 and 31 December 2019 as part of the routine diagnostic activity for diarrhoea in weaned cattle, including a quantitative parasitological analysis coupled with a search for Johne's disease (paratuberculosis). Information on slaughter and carcass weight, inter-farm movements and mortality was obtained from the French national registration database (BDNI). The study was conducted at two levels using adapted categorical RF variables: 1) at the cattle level (>12 months), an estimation of presence of adult parasites using egg count in faecal samples (negative vs. positive) and 2) at the herd level, an estimation of 6-24 months of the dairy heifers exposure to larval forms on the basis of the proportion of dairy cattle shedding eggs in the herd (three classes). At the cattle level, the outcome variables were carcass weight (model 1), case-control status for mortality within 30 days of diagnosis (model 2) and case-control status for slaughter within 365 days of diagnosis (model 3). At the herd level, the outcome variable was the mortality ratio for dairy heifers aged 6-24 months (Model 4). Other important covariates were used to improve model fit. Multivariate analyses were performed using a linear mixed model (model 1), generalised estimating equations (GEE) (models 2 and 3) and a multinomial logistic model (model 4). Overall, 1291 out of 4315 cattle (29.9%) were found to excrete RF eggs and 19.6% of the positives had an excretion score of >200 eggs/g. The prevalence increased steadily with age class and was higher in beef cattle than dairy cattle (42.7% vs. 26.9%) in the years 2015-2019 compared to 2010-2014 (33.3% vs. 26.5%) and in November-February (33.2%) compared to March-June (28.9%) and July-October (27.3%). Rumen fluke variables were not found to be explanatory factors of outcome variables at both animal and herd levels. In contrast, significant negative associations were observed between outcome variables and other health covariates, such as Johne's disease, GI nematode, bovine viral diarrhoea and coccidia statuses. In conclusion, RFs are prevalent in cattle reared in Normandy but this does not result in significant production losses. Therefore, the value to farmers of oxyclozanide treatment at an effective dose for paramphistomosis after simple identification of RF eggs in the faeces seems limited.

Rumen and Liver Fluke Infections in Sheep and Goats in Northern and Southern Germany

Simple Summary

Little is known about the distribution of rumen and liver flukes in sheep and goats in Germany or about the occurring rumen fluke species. These fluke infections can be detected by the parasite’s eggs in the host animal’s feces. Therefore, fecal samples from 223 sheep farms and 143 goat farms from northern and southern Germany were examined. The eggs of rumen flukes were detected on 2.2% of the samples, the eggs of common liver flukes on 2.7%, and the eggs of small liver flukes on 21.1% of the examined sheep farms. The rumen flukes were identified as the emerging species Calicophoron daubneyi. No rumen fluke eggs were detected on any of the goat farm samples, but common and small liver fluke eggs were detected in 5.6% and 7.0% of the goat herds, respectively. Differences in the geographical distribution of rumen and liver flukes between and within the two regions were identified. Rumen flukes were more frequently found in the north, while the two liver fluke species were more frequently found in the south of Germany. Sheep sharing the pasture with other ruminants were more likely to be infected with rumen flukes.

Abstract

Paramphistomidosis has recently been identified as an emerging parasitosis in Europe. This study estimated the prevalence of rumen flukes, Fasciola hepatica and Dicrocoelium dendriticum, in small ruminants in Germany and identified occurring rumen fluke species and potential predictors for fluke infections. Pooled fecal samples from 223 sheep farms and 143 goat farms in northern and southern Germany were examined by the sedimentation technique, and molecular species identification was performed on rumen-fluke-positive samples. In sheep, a flock prevalence of 2.2% was detected for rumen flukes. Calicophoron daubneyi was identified on four of five positive farms, while species identification failed in one flock. No rumen fluke eggs were detected in the examined goat herds. F. hepatica eggs were detected in 2.7% of the sheep flocks, while the herd prevalence was 5.6% in goats. Higher prevalence values of 21.1% (sheep) and 7.0% (goats) were observed for D. dendriticum. Mixed grazing with other ruminants and previously identified infections with rumen flukes and/or F. hepatica were identified as predictors for paramphistomidosis. The distribution of the three trematode species followed a geographical pattern associated with conditions favoring the relevant intermediate hosts. C. daubneyi is an established parasite in German sheep at a currently low prevalence.

The winner takes it all: dominance of Calicophoron daubneyi (Digenea: Paramphistomidae) among flukes in Central European beef cattle

In Europe, paramphistomosis caused by Paramphistomum spp. was historically regarded as being of minor importance. However, Calicophoron daubneyi has recently been recognized as an emerging pathogen in Europe due to its increasing prevalence and negative impact on livestock production. In search for paramphistomid flukes, 5573 beef cattle fecal samples from 115 farms across the whole Czech Republic were examined from March 2019 to June 2021. The eggs of paramphistomid flukes were identified in 29.9% of samples. Internal transcribed spacer 2 sequences from 90 adult flukes and 125 fecal samples collected across Czech Republic confirmed C. daubneyi infection in the Czech beef cattle. Ninety mitochondrial DNA sequences obtained from adult C. daubneyi specimens revealed 13 individual haplotypes, two of them recorded for the first time. Although C. daubneyi is a new parasite in beef cattle herds in the Czechia, it clearly dominates the parasitological findings in the country's beef cattle. The common occurrence of C. daubneyi in most of the beef cattle herds indicates environmental conditions suitable also for the life cycle of Fasciola hepatica and risk of its emergence.

Predicting environmental suitability and geographical distribution of Dicrocoelium dendriticum at littoral of Caspian Sea: An ecological niche-based modeling

Dicrocoeliasisis caused by the small liver fluke (Dicrocoelium spp.), mainly Dicrocoelium dendriticum in domestic and wild ruminants. The small liver fluke is the probable predisposing cause of economic burden. The impact of geographic and climatic factors on the incidence of dicrocoeliasis has been severely ignored in different geographical areas. Due to the lack of data regarding dicrocoeliasis in Iran, this study was aimed to investigate the prevalence and intensity of ovine and bovine Dicrocoelium infection in the coastal strip south of the Caspian Sea. Fecal samples were obtained from the cattle and sheep in three provinces of Guilan, Mazandaran and Golestan at the littoral of the Caspian Sea. All collected samples were then tested by flotation methods for determining the number of eggs per gram of feces (EPG). Moreover, we applied maximum entropy niche-based modeling (MaxEnt), coupled with remote sensing and the Geographical Information System (GIS) to visualize the spatial distribution and risk factors of Dicrocoelium dendriticum at the littoral of Caspian Sea. A total of 2688 stool samples were collected from cattle (n = 1344) and sheep (n = 1344) in coastal provinces of the Caspian Sea including Guilan (n = 1280), Mazandaran (n = 768) and Golestan (n = 640) provinces. Based on the data presented here, the highest rate of infection was observed in Guilan and Mazandaran provinces. The results revealed the prevalence rates of 36.72% and 6.09% for sheep and cattle in Guilan province, respectively. This rate was 22.4% for sheep and 3.91% for cattle in Mazandaran province. However, the rate of sheep infection was 90% in some point locations. Dicrocoelium infection was found to be significantly different between three provinces in sheep (P < 0.00001, Chi = 111.633). Our findings exhibited a high reliability of the MaxEnt model, and area under the curve (AUC) values of the training and test data sets were determined to be 0.852 and 0.818, respectively. Jackknife analysis showed the relative variable contribution to the model performance, where four variables were found as key influential factors that highly affected the habitat suitability of the presence of the lancet fluke including the precipitation of driest quarter (Bio17), altitude, temperature seasonality (Bio4), and precipitation of driest month (Bio14). The findings of this study demonstrated a high presence rate of Dicrocoelium infection at the littoral of Caspian Sea, Iran. Moreover, climatic variables can be considered as important predictive factors affecting the distribution of infection in the studied areas. Further studies based on the findings of the GIS are also very important in the country for planning control programs.

Dicrocoeliosis in extensive sheep farms: a survey

Background

This study investigated the epidemiological and molecular aspects of dicrocoeliosis in extensive sheep farms.

Methods

From 2013 to 2014, copromicroscopical analyses in 190 dairy sheep farms and anatomo-pathological inspections in six slaughterhouses were carried in Sardinia, Italy. Rectal faecal samples were analyzed using the FLOTAC® method, and anatomo-pathological examinations were based on detecting thickened terminal bile ducts (TTBDs). In addition, genetic analyses were conducted on representative DNA samples of adult Dicrocoelium spp.

Results

Ninety-seven (51.1%) out of 190 sheep farms were coprologically positive for Dicrocoelium spp. In the liver, on the surface and cut surface, TTBDs were reported in 40.1% (309/770) and 15.3% (118/770) of the animals examined, respectively, with an overall prevalence of 25.5% (196/770). No intraspecific genetic variation was observed among the Dicrocoelium dendriticum isolates.

Conclusions

Our survey reveals the widespread presence of D. dendriticum in Sardinia, although seasonal, geographical and climatic conditions might be key factors in modulating the infection prevalence. Examining typical lesions due to D. dendriticum in the liver in abattoirs can be used as a marker for tracking chronic dicrocoeliosis infection.

Genotyping of Fasciola hepatica Isolated from Domestic Animals in the West of Iran

OBJECTIVES

The most common parasites responsible for fascioliasis are F. hepatica and F. gigantica. Fascioliasis is an important problem in terms of health and economics. The western part of Iran is one of the major hubs of animal husbandry and the prevalence of fascioliasis is high. The aim of the current study was to determine the Fasciola spp. present in the western part of Iran. In the present study, 45 samples were collected from slaughterhouses in three provinces in the western part of Iran, including Ilam, Lorestan and Kermanshah.

METHODS

The flukes were detected using morphological methods and the DNA of all samples was extracted. The ribosomal internal transcribed spacer (ITS1) was identified by PCR and PCR-RFLP techniques using the Rsa1 restriction enzyme. Then, 15% of the samples were sequenced.

RESULTS

Based on their ITS1 sequence, all samples showed 700 bp bands. The results of sequencing showed a similarity of 99% to 100% across samples. Using the Rsa1 restriction enzyme, all samples produced three distinct bands (60 bp, 100 bp, and 360 bp). These results demonstrated that the most common fasciola in the western part of Iran in sheep and cattle is F. hepatica.

CONCLUSION

The results of the present study showed that only the species F. hepatica is parasitizing livestock in the western part of Iran. Further studies using new molecular markers for more accurate identification of fasciola-causing species will be useful in the control and prevention of fascioliasis.

Spatial patterns of Fasciola hepatica and Calicophoron daubneyi infections in ruminants in Ireland and modelling of C. daubneyi infection

Background

Fasciola hepatica has always represented a threat to Irish livestock because the Irish climate is highly suitable for the main local intermediate host of the parasite, the snail Galba truncatula. The recent clinical emergence of infections due to Calicophoron daubneyi has raised the question of whether the two parasites, which share a niche during part of their life-cycles, interact in some way. Here, we used geographical information systems (GIS) to analyse the distribution of both parasites in cattle and sheep. We also developed the first predictive model of paramphistomosis in Ireland.

Results

Our results indicated that, in cattle, liver fluke infection is less common than rumen fluke infection and does not exhibit the same seasonal fluctuations. Overall, we found that cattle had a higher likelihood of being infected with rumen fluke than sheep (OR = 3.134, P < 0.01). In addition, infection with one parasite increased the odds of infection with the other in both host species. Rumen fluke in cattle showed the highest spatial density of infection. Environmental variables such as soil drainage, land cover and habitat appeared to be the most important risk factors for C. daubneyi infection, followed by rainfall and vegetation. Overall the risk of infection with this parasite was predicted to be higher in the west of the country.

Conclusions

This study shows differences between the infection rates and spatial patterns of bovine and ovine infections with F. hepatica and C. daubneyi in Ireland. Whether the reasons for this are due to susceptibility, exposure and/or management factors is yet to be determined. Furthermore, the rumen fluke model indicates distinct risk factors and predicted distribution to those of F. hepatica, suggesting potential biological differences between both parasite species.

Dicrocoelium Dentriticum in Explanted Liver: Report of an Unusual Finding

Dicrocoelium dentriticum, a member of trematode type helminths, is a liver parasite of ruminants. Humans are infected accidentally by ingestion of intermediate host, through infected ants via eating of raw vegetables or drinking of contaminated water. Infection is often asymptomatic or results in subtle symptoms; therefore, infections are usually unrecognized. However, it can produce chronic cholangitis and swelling or adenomatous proliferation in the bile ducts and lead to abdominal pain, diarrhea, fatigue, jaundice, and other symptoms. We report a 49-year-old female patient with end-stage hepatic cirrhosis from viral hepatitis B and D coinfection who underwent liver transplant. Shortly after transplant, she developed symptoms suggesting an obstructed biliary duct. Liver needle biopsy was done 24 hours after transplant to rule out rejection. Biopsy of her explanted liver was also examined pathologically. Microscopic examination of the liver needle biopsy ruled out rejection. Prepared sections of explanted liver revealed a helminth in the common bile duct. Morphologic reconstruction of helminth by microscopic findings and consultation with an expert parasitologist supported the diagnosis of Dicrocoelium dentriticum.

Ruminal paramphistomosis in cattle from northeastern Algeria: prevalence, parasite burdens and species identification

Slaughterhouse samples were analysed over a two-year period (September 2010-August 2012) in Jijel (northeastern Algeria) in order to determine seasonal variations in the prevalence and intensity of bovine paramphistomosis in a Mediterranean climate and identify paramphistome species using molecular biology. In spring and summer, significantly higher prevalences and lower parasite burdens were noted in bull calves, thus indicating an effect of season on these parameters. In contrast, the differences among seasonal prevalences or among seasonal parasite burdens were not significant in the case of old cows. Eleven adult worms from the slaughterhouses of Jijel and three neighbouring departments (Constantine, El Tarf and Setif) were analysed using molecular markers for species identification. Two different species, Calicophoron daubneyi and C. microbothrium, were found. The presence of these two paramphistomids raises the question of their respective frequency in the definitive host and local intermediate hosts.

Antigen characterization from second instars of oestrid bot flies for the detection of anti-Cephenemyia stimulator antibodies by ELISA in roe deer (Capreolus capreolus)

A study to determine the most appropriate antigen for use in the serodiagnosis of Cephenemyia (Diptera: Oestridae) infestation in roe deer (Capreolus capreolus) was carried out using immunoenzymatic tests. Serum samples from 43 roe deer from northern Spain were obtained post-mortem and corresponding numbers of bot fly larvae established. Three antigen complexes were tested, including Cephenemyia stimulator Clark excretory/secretory antigens (CsES), C. stimulator somatic antigens (CsSA) and Oestrus ovis L. (Diptera: Oestridae) excretory/secretory antigens (OoES). In addition, the composition of each antigen was analysed using an electrophoresis system. Cephenemyia stimulator larvae were found in 25% of roe deer; the mean intensity of infection was 24.3 larvae per infested animal. In the antigen analysis, CsSA showed four exclusive bands of molecular weight (17-19, 62, 65 and 67-70 kDa). A positive correlation between immunoglobulin G (IgG) values and total number of larvae was found with CsES and CsSA. The highest sensitivity value, negative predictive value and negative likelihood ratio were obtained using CsES. The highest specificity value, positive likelihood ratio and kappa value were achieved with CsSA. The predictive values of the enzyme-linked immunosorbent assay (ELISA) using CsES and CsSA reached statistical significance and seroprevalence values were 26-44%. The use of ELISA with CsES and CsSA seems promising in the non-invasive diagnosis of Cephenemyia infestation in roe deer.

Gastrointestinal nematode infections in roe deer (Capreolus capreolus) from the NW of the Iberian Peninsula: assessment of some risk factors

Intestinal contents of 218 roe deer hunted in the northwest (NW) of the Iberian Peninsula during the 2008-2009 hunting seasons were examined in order to provide information on the gastrointestinal (GI) nematode prevalence and intensity of infection and the possible influence of some environmental and intrinsic factors such as climatic conditions, age and sex. All the animals studied harboured GI nematodes, and a total of 20 different species belonging to ten genera were identified. Spiculopteragia spiculoptera/Spiculopteragia mathevossiani, Ostertagia leptospicularis/Ostertagia kolchida and Nematodirus filicollis were the most common. This is the first citation for Chabertia ovina, Cooperia pectinata, Cooperia punctata, Cooperia oncophora, Haemonchus contortus, Nematodirus spathiger, Oesophagostomum venulosum, Teladorsagia trifurcata, Trichostrongylus capricola, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Trichuris capreoli in roe deer from the Iberian Peninsula. Prevalence and intensity were significantly higher in the abomasum, where infections with more than one GI nematode species were the most common; in the other intestinal segments infections with only one GI nematode species were the most prevalent. When considering the influence of the different risk factors on the prevalence of GI nematodes, the highest prevalence for most of the genera were observed in roe deer from coastal areas, where climatic conditions are more favourable for the development and survival of third stage larvae in the environment. Regarding the sex of the animals, the prevalence was, in general, higher in males than in females, probably due to behavioural and physiological sex-related differences. On the contrary, no differences were found in relation to the age of the animals. This study reveals that roe deer from the NW of the Iberian Peninsula are widely and intensely infected with gastrointestinal nematodes, which probably affect the health status of these ungulates.

Paramphistomum daubneyi: characteristics of infection in three lymnaeid species

Experimental infections of two South American lymnaeids (Lymnaea neotropica and L. viatrix var. ventricosa) with Paramphistomum daubneyi were carried out to determine if these snail species could sustain larval development of this digenean and, if so, to specify their potential for cercarial production. A French population of Galba truncatula infected and raised according to the same protocol served as controls. In both experiments, prevalence of P. daubneyi infections in snails did not significantly differ from each other. In snail groups evaluated for cercarial shedding (first experiment), a significantly lower number of shed cercariae was noted for L. neotropica, while those from G. truncatula and L. v. ventricosa did not differ significantly from each other. Dissection of infected snails at day 65 post-exposure at 20 °C (second experiment) found significantly lower burdens of P. daubneyi rediae and cercariae in the bodies of L. neotropica than in those of G. truncatula and L. v. ventricosa. Compared to total cercarial production observed in dissected snails, the percentage of cercariae which exited from snails was 75.6% for G. truncatula, 21.6% for L. neotropica, and 91.4% for L. v. ventricosa. This last species seems to be a good candidate for metacercarial production of P. daubneyi.

Bovine paramphistomosis in Galicia (Spain): prevalence, intensity, aetiology and geospatial distribution of the infection

The present study explored various basic aspects of the epidemiology of paramphistomosis in Galicia, the main cattle producing region in Spain. In total, 589 cows from different farms located across the region were selected at random in the slaughterhouse for examination of the rumens and reticula for the presence of Paramphistomidae flukes. Paramphistomes were found in 111 of 589 necropsied cows (18.8%; 95% CI: 15.7-21.9%), with higher prevalences of infection in beef cows than in dairy cows (29.2% vs 13.9%). Although the number of flukes per animal was generally low (median=266 flukes), some cows harboured large parasite burdens (up to 11,895 flukes), which may have harmful effects on their health or productivity. Cows with higher parasite burdens also excreted greater numbers of fluke eggs in their faeces, which suggests that heavily parasitized mature cows play an important role in the transmission of paramphistomosis. This role may be particularly important in Galicia, where the roe deer, which is the only wild ruminant in the study area, was found not to be a reservoir for the infection. The use of morpho-anatomical and molecular techniques applied to a large number of fluke specimens provided reliable confirmation that Calicophoron daubneyi is the only species of the family Paramphistomidae that parasitizes cattle in Galicia. The environmental data from the farms of origin of the necropsied cows were used in Bayesian geostatistical models to predict the probability of infection by C. daubneyi throughout the region. The results revealed the role of environmental risk factors in explaining the geographical heterogeneity in the probability of infection in beef and dairy cattle. These explanatory factors were used to construct predictive maps showing the areas with the highest predicted risk of infection as well as the uncertainty associated with the predictions.

Covariate selection in multivariate spatial analysis of ovine parasitic infection

Gastrointestinal (GI) strongyle and fluke infections remain one of the main constraints on health and productivity in sheep dairy production. A cross-sectional survey was conducted in 2004-2005 on ovine farms in the Campania region of southern Italy in order to evaluate the prevalence of Haemonchus contortus, Fasciola hepatica, Dicrocoelium dendriticum and Calicophoron daubneyi from among other parasitic infections. In the present work, we focused on the role of the ecological characteristics of the pasture environment while accounting for the underlying long range geographical risk pattern. Bayesian multivariate spatial statistical analysis was used. A systematic grid (10 km×10 km) sampling approach was used. Laboratory procedures were based on the FLOTAC technique to detect and count eggs of helminths. A Geographical Information System (GIS) was constructed by using environmental data layers. Data on each of these layers were then extracted for pasturing areas that were previously digitalized aerial images of the ovine farms. Bayesian multivariate statistical analyses, including improper multivariate conditional autoregressive models, were used to select covariates on a multivariate spatially structured risk surface. Out of the 121 tested farms, 109 were positive for H. contortus, 81 for D. dendriticum, 17 for C. daubneyi and 15 for F. hepatica. The statistical analysis highlighted a north-south long range spatially structured pattern. This geographical pattern is treated here as a confounder, because the main interest was in the causal role of ecological covariates at the level of each pasturing area. A high percentage of pasture and impermeable soil were strong predictors of F. hepatica risk and a high percentage of wood was a strong predictor of C. daubneyi. A high percentage of wood, rocks and arable soil with sparse trees explained the spatial distribution of D. dendriticum. Sparse vegetation, river, mixed soil and permeable soil explained the spatial distribution of the H. contortus. Bayesian multivariate spatial analysis of parasitic infections with covariates from remote sensing at a very small geographical level allowed us to identify relevant risk predictors. All the covariates selected are consistent with the life cycles of the helminths investigated. This research showed the utility of appropriate GIS-driven surveillance systems. Moreover, spatial features can be used to tailor sampling design where the sampling fraction can be a function of remote sensing covariables.

Prevalence and intensity of Paramphistomum daubneyi infections in cattle from north-eastern Algeria

Parasitological investigations on ruminal paramphistomosis were carried out in 2033 cattle over a 14-month period in three Algerian slaughterhouses to determine the prevalence and intensity of this disease. The prevalence of infection varied from different slaughterhouses (1.2% at El Khroub, 7.5% at Ferdjioua and 12.1% at Jijel). The worm burden was significantly higher in cattle from El Khroub than for those slaughtered in the other two sites (a mean of 984.1 parasites compared with 87.5 and 140.7 at Jijel and Ferdjioua, respectively). No significant correlation between prevalence, intensity of infection and age of cattle was noted. Overall, females were significantly more infected than males, whereas the sex of animals was independent of worm burdens recovered in slaughtered cattle. The climatic conditions of provinces in which the slaughterhouses were located (a more temperate climate for Jijel and semiarid conditions for the other two provinces) may partly explain variations noted in prevalence and intensity of infection. The present results will contribute to our understanding of the epidemiology of Paramphistomum daubneyi infections in north-eastern Algeria.