Paramphistomum daubneyi: the number of sporocysts developing in experimentally and naturally infected Galba truncatula

In-herd prevalence of Fasciola hepatica and Calicophoron / Paramphistomum spp. infections in German dairy cows with comparison of two coproscopical methods and establishment of real-time pyrosequencing for rumen fluke species differentiation

Infections with liver and rumen flukes are among the most frequent parasitic diseases in cattle worldwide. In Europe, the predominant liver fluke species is Fasciola hepatica, and the recently rapidly spreading rumen flukes are mostly Calicophoron daubneyi and occasionally Paramphistomum leydeni. In this study, 1638 faecal samples from individual dairy cows from 24 northern and 18 southern German farms as well as one central German farm, all preselected for potential F. hepatica infection, were examined to determine in-herd prevalences of liver and rumen fluke infections. Furthermore, individual faecal egg counts (FECs) were determined in the northern and central German cows. On farms with patent F. hepatica infections, the mean in-herd prevalence was 15.8% in northern Germany, 41.6% in southern Germany and 14.0% in the central German farm. Rumen fluke infections resulted in high in-herd prevalences in all regions with a mean prevalence of 46.0% in northern, 48.4% in southern and 40.0% in central Germany. Individual FECs varied between 0.1 and 4.1 (mean 0.4) eggs per gram faeces (EPG) for F. hepatica and between 0.1 and 292.4 (mean 16.9) EPG for rumen flukes. Mean in-herd prevalence and mean FECs did not differ significantly between mono- and coinfected farms for either fluke species. Comparison of the classical sedimentation technique and the Flukefinder® method on a subset of 500 faecal samples revealed a similar number of positive samples, however, Flukefinder® mean FECs were three to four times higher for liver and rumen fluke eggs, respectively, with an increasing gap between EPG levels with rising egg counts. Fluke egg size measurement confirmed P. leydeni eggs on average to be larger in length and width (161.0 µm x 87.1 µm) than those of C. daubneyi (141.8 µm x 72.9 µm). However, due to overlap of measurements, morphological species identification based on egg size proved unreliable. For accurate identification, a real-time pyrosequencing approach was established, offering the advantage over classical Sanger sequencing of unambiguously identifying rumen fluke mixed species infections. Real-time pyrosequencing confirmed C. daubneyi (78.1% [50/64]) as the predominant rumen fluke species in Germany, while P. leydeni was detected in 12.5% (8/64) of sampled cows. A total of 9.4% (6/64) cows were infected with both C. daubneyi and P. leydeni, representing the first finding of a mixed infection in domestic ruminants in Europe to date.

Evaluation of Fasciola hepatica Infections in Cattle in Northeastern Algeria and the Effects on Both Enzyme and Hepatic Damage, Confirmed by Scanning Electron Microscopy

PURPOSE

The aim of our study is to establish the presence of Fasciola hepatica on farms in northeastern Algeria.

METHODS

143 blood and coprological samples of 15 males and 128 females of different breeds and ages were analysed.

RESULTS

Our study indicates a heterogeneous level of the anti-f2 antibodies to Fasciola hepatica in response to the infection. The overall seroprevalence was about 22.37%, and 9 out of 13 investigated farms were infected, with rates varying from 5.88% to 70%. To explain the intrinsic variability of the infection, we identified age, sex and breed as potential risk factors. Based on this, we collected information about their relevance. There was a significant difference for age (p = 0.018) and coprology (p < 0.0001). Independently, sex and breed had no impact on the infection, although males were more infected (27%) than females (22%). Of the five investigated breeds, Holstein cattle (31.11%) were most affected, followed by Montbeliard (20.27%) and crossed breed (13.64%). Multivariate comparisons showed that the presence of faecal eggs reflects the active infectious status of cattle (p < 0.0001), while age (p = 0.011) and sex (p = 0.040) significantly impact the chance of acquiring the infection. To evaluate liver parenchyma integrity and its functionality, hepatic enzymes were examined and showed relatively low levels of aminotransferases, excluding cytolisis. Although sensitive to distomatosis, γGT and PAL values were inconsistent with the infection rate. The relatively high levels of proteins and albumin eliminate hepatic insufficiency.

CONCLUSION

Our results suggest a chronic fasciolosis, confirmed by histology and SEM.

The prevalence and development of digenean parasites within their intermediate snail host, Galba truncatula, in a geographic area where the presence of Calicophoron daubneyi has recently been confirmed

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C. daubneyi, F. hepatica and H. cylindracea all commonly infect UK G. truncatula.

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C. daubneyi may be less adept at infecting and developing in UK G. truncatula.

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Paramphistomosis risk in the UK may increase if C. daubneyi can adapt to this host.

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Evidence of interactions between digenean species infecting G. truncatula.

During the past decade, rumen fluke (Calicophoron daubneyi) has established as a prominent parasite of livestock within numerous European countries. Its development and spread is enabled by the presence of its intermediate snail host G. truncatula. However, the dynamics of this stage of the C. daubneyi lifecycle is yet to be recorded in numerous northern European countries including the UK. Here, the prevalence of C. daubneyi along with F. hepatica, H. cylindracea and other parasites infecting G. truncatula snails on 10 Welsh farms was recorded using morphological and PCR techniques.

A total of 892 G. truncatula snails were collected between May and October 2016. The prevalence of C. daubneyi in sampled G. truncatula snails (4%) was lower compared to F. hepatica (5.6%). No association in prevalence between these species was recorded. Haplometra cylindracea was found infecting 8.2% of G. truncatula snails, with its prevalence within G. truncatula populations negatively associated with F. hepatica cercariae prevalence (P = 0.004). Generalized estimation equation (GEE) linear regression models identified the levels of respective fluke eggs shed onto pasture as the main significant association between prevalence levels of both C. daubneyi and F. hepatica within G. truncatula populations (P < 0.001). However, equivalent prevalence levels of C. daubneyi and F. hepatica within G. truncatula populations were associated with higher C. daubneyi egg outputs and lower F. hepatica egg outputs from livestock grazing the G. truncatula habitats. Only one of 36C. daubneyi infected G. truncatula snails was found harbouring its cercarial stages, a significantly lower proportion compared to the 29 of 50 F. hepatica infected G. truncatula harbouring its respective cercariae (P < 0.05).

These results signify that C. daubneyi may be less adept at infecting and developing in the UK’s native G. truncatula populations in comparison with F. hepatica. However, C. daubneyi has previously demonstrated its ability to progressively adapt to an intermediate host in a new environment. If C. daubneyi were to adapt to infect and develop more efficiently in UK G. truncatula populations, paramphistomosis risk would significantly increase leading to increased livestock losses. Questions are also raised regarding potential interaction between digenean species at intermediate snail host level, which could impact subsequent livestock trematodosis risk.