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The liver fluke, Fasciola hepatica, is one of the major parasite threats to livestock industries world-wide. In sheep and cattle, F. hepatica infection is commonly diagnosed using a range of methods. Aside from conventional coprological and serological diagnostic methods, there are also several molecular methods available based on the detection of liver fluke DNA in faeces. In this study, the outcomes of faecal egg count (FEC), serology and coproantigen ELISA (cELISA) were compared with the performance of polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) in diagnosis of F. hepatica from naturally infected cattle and sheep. A total of 64 individual faecal and serum samples were collected from four sheep and beef cattle herds with previous histories of F. hepatica infection. FEC and coproantigen levels were measured in faecal samples and anti-F.hepatica antibody levels were measured in serum samples. DNA samples isolated from faeces were examined both by PCR and LAMP, targeting the internal transcribed spacer 2 (ITS2) region of the F. hepatica genome. Results showed that F. hepatica eggs were present in 28 animals, while coproantigen and specific anti-F. hepatica antibodies were detected in 36 and 53 animals, respectively. Only 3 and 6 samples were positive by PCR and LAMP, respectively. To calculate method specificity and sensitivity, a combination of FEC and cELISA was selected as the composite reference standard (CRS). When compared to the CRS, PCR had a sensitivity of 10.7% and specificity of 100%, whereas LAMP had a sensitivity and specificity of 17.9% and 97.2%, respectively. PCR and LAMP in this field study were highly specific, but both had poor sensitivity compared with FEC and cELISA. Potential reasons for PCR and LAMP failure were inadequate amounts of amplifiable F. hepatica DNA, possibly due to the choice of DNA extraction procedure, amount of faecal material processed, as well as different faeces consistency and composition between different animal species.

Micro-computed tomography (micro-CT) is an exceptional imaging modality which is limited in visualizing soft biological tissues that need pre-examination contrasting steps, which can cause serious deformation to sizeable specimens like engorged ticks. The aim of this study was to develop a new technique to bypass these limitations and allow the imaging of fed ticks in their natural state. To accomplish this, adult Ixodes ricinus females were allowed to engorge in vitro on blood supplemented with PEGylated gold nanoparticles (PEG-AuNPs). In total, 73/120 females divided into 6 groups engorged on blood enriched with 0.07–2.16 mg PEG-AuNPs per ml of blood. No toxic effect was observed for any of the tested groups compared to the control group, in which 12/20 females engorged on clear blood. The ticks were scanned on a Bruker micro-CT SkyScan 1276. The mean radiodensity of the examined ticks exceeded 0 Hounsfield Units only in the case of the two groups with the highest concentration. The best contrast was observed in ticks engorged on blood with the highest tested concentration of 2.16 mg/mL PEG-AuNPs. In these ticks, the midgut and rectal sac were clearly visible. Also, the midgut lumen volume was computed from segmented image data. The reduction in midgut volume was documented during the egg development process. According to this pilot study, micro-CT of ticks engorged on blood supplemented with contrasting agents in vitro may reveal additional information regarding the engorged ticks’ anatomy.

Transmission patterns of Fasciola hepatica were investigated on beef cattle (n = 3) and sheep (n = 3) farms in Sweden between 2011 and 2012. The dynamics of fluke infection, particularly estimated time of infection, were screened each grazing season by ELISA detection of antibodies in lambs (n = 94) and first grazing season calves (n = 61). Colostral transfer of F. hepatica antibodies from seropositive ewes was detected in sheep up to 11 weeks of age. In sheep, the estimated time of infection differed significantly between herds and years. Typical 'winter infection' was observed on two sheep farms in 2012, but the most prevalent transmission pattern was found to be 'summer infection', characterised by infection of animals in late summer by F. hepatica originating from overwintered and/or spring-excreted eggs. In contrast, beef calves were infected mainly in September-October ('summer infection'). Furthermore, lymnaeid and succineid snails were collected on the pastures used by these animals both in spring and in the autumn each year. In total, 1726, 588, 138, 130, 93 and 42 specimens of Galba truncatula, Lymnaea palustris, Lymnaea glabra, Lymnaea fuscus, Radix peregra and Succinea putris, respectively, were collected and identified. These were subsequently examined for the presence of F. hepatica DNA by species-specific PCR and the findings compared against mean monthly rainfall and temperature data for each farm. The main intermediate host of the liver fluke was G. truncatula, with a prevalence range of F. hepatica infection from 0% to 82%. Only 1 out of 42 terrestrial S. putris tested positive for F. hepatica, casting doubt on the role of this species in transmission of F. hepatica in Sweden. In conclusion, two main peak periods of infection were observed: May-June (from overwintered infected snails = 'winter infection') and August-September (from metacercariae developed and produced by snails during summer = 'summer infection'). The occurrence and frequency of 'winter infection' were dependent on local environmental factors such as snail habitat availability or grazing behaviour of animals, rather than on climatic factors.