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

Molecular uncovering of important helminth species in wild ruminants in the Czech Republic

Monitoring gastrointestinal helminth infections in wild ruminants poses significant challenges for managing wildlife health, particularly regarding invasive species. Traditional coprological methods are often limited by their labor-intensive nature and potential for erroneous identification due to morphological similarities among parasite species. This study employed advanced molecular techniques to assess the prevalence and distribution of several helminth taxa, including the invasive nematode Ashworthius sidemi and the trematode Fascioloides magna, in wild ruminant populations in the Czech Republic (CR). A comprehensive and extensive survey on parasite occurrence, unique in its nationwide scope, was conducted on 983 fecal samples collected from red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), and mouflon (Ovis musimon) across various regions of the CR. The samples were analyzed using multiplex real-time PCR assays specifically designed to detect the DNA of six helminth representatives: the nematodes A. sidemi and Haemonchus spp., as well as the trematodes F. magna, Dicrocoelium dendriticum, Fasciola hepatica, and Calicophoron daubneyi (and representatives of the family Paramphistomidae, respectively). These assays targeted regions of ribosomal DNA (rDNA) and were designed to exhibit high sensitivity and specificity, enabling accurate detection of helminth parasites directly in fecal samples. The molecular assays revealed that invasive nematode A. sidemi was the most prevalent helminth species, detected in 15.8% of all samples (155/983), with the highest infection rate observed in red deer at 30.7% (124/404). Haemonchus spp. were also frequently detected, identified in 14.9% of samples (146/983), particularly in roe deer, with a prevalence of 23.2% (86/371). Spatial analysis of these nematodes across various regions of the CR revealed the extensive distribution of both A. sidemi and Haemonchus spp. in nearly all regions. In contrast, trematode infections were less common, with F. magna and D. dendriticum each found in only 1.5% of samples (15/983). Members of the family Paramphistomidae were detected in 0.2% of the samples (2/983) and were confirmed through sequencing as C. daubneyi. The geographical distribution patterns identified in this study indicate potential hotspots for specific helminth species. These findings are critical for planning health management and conservation strategies to mitigate the impacts of helminth infections, especially in areas affected by invasive species.

Prevalence, risk factors and molecular identification of paramphistomid species in sheep from a Spanish endemic area

BACKGROUND

Paramphistomids are ruminal trematodes that cause important losses in tropical and subtropical regions. However, their presence in Europe has increased significantly in recent decades. In northwestern Spain, this trend has been confirmed in cattle, but data in sheep are scarce and not updated. Moreover, the paramphistomid species affecting sheep in the area have never been molecularly identified. To evaluate the prevalence of paramphistomid infections in sheep from northwestern Spain, 826 faecal samples from 25 sheep farms were collected and analysed via coproscopic techniques. In addition, the rumens of 85 roe deer from the same area were examined to detect adult paramphistomids. The species present were molecularly identified. Multivariate analyses for identifying the risk factors affecting the prevalence and egg shedding of rumen flukes were also performed.

RESULTS

Overall, 14% of the animals and 44% of the flocks were positive; the mean egg count was 20.5 eggs per gram of faeces. In contrast, no adult paramphistomids were found in roe deer. Older sheep, those from farms located in the central climatic area, without water throughs available on pastures and using their own manure to fertilize, were considered significantly more susceptible to infection with paramphistomids. With respect to egg shedding, animals from 37 to 72 months of age, farms under semiextensive management, and those coinfected with Fasciola hepatica presented significantly greater egg counts. Molecular identification revealed 100% similarity with Calicophoron daubneyi sequences from other European and Mediterranean countries.

CONCLUSIONS

The present study confirms the increase in the prevalence of paramphistomid infections in sheep in the area with high dissemination of the parasite, as previously reported in cattle, and represents the first molecular identification of C. daubneyi in sheep from Spain. Our results demonstrate that special attention should be given to adult animals since they are the main carriers and are responsible for environmental contamination. In addition, detecting risk areas and applying effective control management measures such as the installation of watering points on pastures seems essential for limiting infections in livestock, especially in sheep, since they are susceptible to developing clinical paramphistomidosis at any time in their lives. The absence of adult flukes in roe deer suggests that they represent less suitable hosts for this trematode than cattle and sheep, although more robust studies monitoring the situation in sympatric areas with domestic ruminants are needed.

Visualization and development of colorimetric loop-mediated isothermal amplification for the rapid detection and diagnosis of paramphistome infection: colorimetric PAR-LAMP

Colorimetric detection can be applied to differentiate between positive and negative conditions. It can be coupled with loop-mediated isothermal amplification to diagnose rumen fluke or paramphistome infection, also called colorimetric PAR-LAMP. This study conducted LAMP using three candidate indicator dyes, namely malachite green (MLG), methyl green (MTG), and neutral red (NTR), and the results were observed by the naked eye. The dye concentration was optimized to obtain the most pronounced positive-negative result discrimination. Subsequently, we conducted target sensitivity tests using the DNA of Fischoederius elongatus at different concentrations. To validate the detection accuracy, the result was confirmed by gel electrophoresis. The sensitivity test presented the lowest detectable DNA concentration or limit of detection (LOD), with 1 pg for MLG, 0.5 ng for MTG, and 50 pg for NTR. Different LODs revealed inhibition of LAMP reaction and reduced efficiency of result presentation for colorimetric-based detection, particularly NTR and MTG. For MLG-LAMP, we observed no cross-reaction of non-target DNA and improved reaction with the DNA of Fischoederius cobboldi and Calicophoron sp., with multi-detection. In addition, naked eye observation and agarose gel electrophoresis (AGE) evaluation of the MLG-LAMP results showed a moderate and strong agreement with LAMP-AGE and microscopic examinations. Based on our results, colorimetric PAR-LAMP is a rapid, comfortable, and point-of-care procedure for the diagnosis of paramphistome infection.

Comparison of Mini-FLOTAC, Flukefinder and sedimentation techniques for detection and quantification of Fasciola hepatica and Calicophoron daubneyi eggs using spiked and naturally infected bovine faecal samples

BACKGROUND

Fasciolosis (Fasciola hepatica) and paramphistomosis (Calicophoron daubneyi) are two important infections of livestock. Calicophoron daubneyi is the predominant Paramphistomidae species in Europe, and its prevalence has increased in the last 10-15 years. In Italy, evidence suggests that the prevalence of F. hepatica in ruminants is low in the southern part, but C. daubneyi has been recently reported at high prevalence in the same area. Given the importance of reliable tools for liver and rumen fluke diagnosis in ruminants, this study evaluated the diagnostic performance of the Mini-FLOTAC (MF), Flukefinder(R) (FF) and sedimentation (SED) techniques to detect and quantify F. hepatica and C. daubneyi eggs using spiked and naturally infected cattle faecal samples.

METHODS

Briefly, negative bovine faecal samples were artificially spiked with either F. hepatica or C. daubneyi eggs to achieve different egg count levels: 10, 50 and 100 eggs per gram (EPG) of faeces. Moreover, ten naturally infected cattle farms from southern Italy with either F. hepatica and/or C. daubneyi were selected. For each farm, the samples were analysed individually only with MF technique and as pools using MF, FF and SED techniques. Bayesian latent class analysis (LCA) was used to estimate sensitivity and accuracy of the predicted intensity of infection as well as the infection rate in the naturally infected farms.

RESULTS

The outcome of this study showed that the highest number of eggs (F. hepatica and C. daubneyi) recovered was obtained with MF, followed by FF and SED in spiked infected samples at 50 and 100 EPG, while at lower infection levels of 10 EPG, FF gave the best results. Moreover, the sensitivity for all the techniques included in the study was estimated at > 90% at infection levels > 20 EPG for both F. hepatica and C. daubneyi eggs. However, MF was the most accurate of the three techniques evaluated to estimate fluke infection intensity. Nevertheless, all three techniques can potentially estimate infection rate at farm level accurately.

CONCLUSIONS

Optimization and standardization of techniques are needed to improve the FEC of fluke eggs.

Calicophoron daubneyi (Dinnik, 1962) (Digenea) in beef and dairy cattle in the Czech Republic: prevalence and drug efficacy

A total of 1,724 beef and 2,941 dairy cattle older than one year from 66 beef and 67 dairy farms in the Czech Republic were examined for the presence of rumen and liver fluke eggs in 2019-2022. Out of 227 positive animals, all were positive for paramphistome and five for fasciolid eggs. Molecular analysis of the ITS2 rDNA revealed the presence of Calicophoron daubneyi (Dinnik, 1962) and Fasciola hepatica Linnaeus, 1758. Faecal egg count (FEC) showed low infection intensity (12 EPG) in animals infected with F. hepatica and high variability in C. daubneyi infections (2-589 EPG). Efficacy of oxyclozanide, albendazole, ivermectin, and closantel against C. daubneyi infection was evaluated at eight beef cattle herds. Faecal samples were collected from all positive animals at 0 and 21days post-treatment. Based on FEC, albendazole, ivermectin and closantel reduced the number of C. daubneyi eggs shed by 0-9.9%, with no effect on the number of infected animals. The use of oxyclozanide on two beef farms showed 100% efficacy against C. daubneyi and F. hepatica. Follow-up examination 5-6 months after drug application showed reinfection of most animals with C. daubneyi, but the FEC was significantly lower. The finding of four dairy cows infected with C. daubneyi housed in a stable without pasture suggests the possibility of the infection being introduced through roughage.