Caroline F. Frey

Fasciola hepatica is a trematode parasite responsible for fasciolosis, a liver disease that affects humans and livestock worldwide. Together with other food-borne trematode infections, fasciolosis is considered a neglected tropical disease. Further, it imposes substantial agricultural losses due to infections in ruminants. No vaccine is currently available, and control heavily relies on drug treatment, especially with triclabendazole (TCBZ). However, the intensive use of TCBZ over the past four decades has led to increasing rates of treatment failures and the emergence of drug-resistant parasites. Therefore, the identification of new treatment options is an urgent priority. The currently available toolset for drug screening, however, is limited. To address this need, we established a novel, semi-automated, standardized, and objective screening assay based on motility monitoring of newly excysted juveniles using microscopic live imaging. The assay was validated by testing a panel of ten compounds with known anthelmintic properties, amongst them TCBZ (IC ₅₀ : 1.5 µM) and the new activator of the F. hepatica transient receptor potential melastatin (TRPM _PZQ ) ion channel, benzamidoquinazolinone (IC ₅₀ : 1.05 µM). In addition to these two compounds with known activity against F. hepatica , three compounds were identified as particularly promising with a fast onset of action and IC ₅₀ values in the nanomolar range: the salicylanilides MMV665807 (IC ₅₀ : 44 nM), niclosamide (IC ₅₀ : 32 nM), and its ethanolamine salt, niclosamide ethanolamine (IC ₅₀ : 9 nM). Complementary live/dead staining revealed that only TCBZ displayed parasiticidal activity, while the other compounds, although leading to parasite paralysis, did not lead to parasite death within 72 hours. Scanning electron microscopy of drug treated parasites did not reveal any significant damage at concentrations corresponding to the IC ₅₀ s, but strong phenotypes were visible at 20 µM. The presented motility assay provides a robust method for the discovery of novel anthelmintic compounds and facilitates the ongoing effort to combat fasciolosis.

Fasciola hepatica is a trematode parasite responsible for fasciolosis, a liver disease that affects humans and livestock worldwide. Together with other food-borne trematode infections, fasciolosis is considered a neglected tropical disease. Further, it imposes substantial agricultural losses due to infections in ruminants. No vaccine is currently available, and control heavily relies on drug treatment, especially with triclabendazole (TCBZ). However, the intensive use of TCBZ over the past four decades has led to increasing rates of treatment failures and the emergence of drug-resistant parasites. Therefore, the identification of new treatment options is an urgent priority. The currently available toolset for drug screening, however, is limited. To address this need, we established a novel, semi-automated, standardized, and objective screening assay based on motility monitoring of newly excysted juveniles using microscopic live imaging. The assay was validated by testing a panel of ten compounds with known anthelmintic properties, amongst them TCBZ (IC50: 1.5 µM) and the new activator of the F. hepatica transient receptor potential melastatin (TRPM) ion channel, benzamidoquinazolinone (IC50: 1.05 µM). In addition to these two compounds with known activity against F. hepatica , three compounds were identified as particularly promising with a fast onset of action and IC50 values in the nanomolar range: the salicylanilides MMV665807 (IC50: 44 nM), niclosamide (IC50: 32 nM), and its ethanolamine salt, niclosamide ethanolamine (IC50: 9 nM). Complementary live/dead staining revealed that only TCBZ displayed parasiticidal activity, while the other compounds, although leading to parasite paralysis, did not lead to parasite death within 72 hours. Scanning electron microscopy of drug treated parasites did not reveal any significant damage at concentrations corresponding to the IC50s, but strong phenotypes were visible at 20 µM. The presented motility assay provides a robust method for the discovery of novel anthelmintic compounds and facilitates the ongoing effort to combat fasciolosis.

Health monitoring based on post-mortem examination is essential for the management of endangered animal species. This is especially true for reintroduced species living in small populations with low genetic diversity, such as the Eurasian lynx ( Lynx lynx ) in Switzerland. Thanks to systematic post-mortem examinations, the Institute for Fish and Wildlife Health (FIWI), University of Bern, has acquired a comprehensive view of the lynx health in Switzerland. This study provides an updated overview of the causes of morbidity and mortality in the Eurasian lynx in Switzerland from 2000 to 2022. A total of 346 necropsied lynx (found dead, euthanized, or culled) were included in this study, and a cause of death (COD) was identified in 318 of them (91.9%). Overall, the main COD was blunt trauma (n = 183, 52.9% - largely vehicular collision). Starvation, resulting from the separation of dependent juveniles from their mother, was the second most frequent COD (n = 63, 18.2%). Fatal infectious diseases were relatively low (n = 32, 9.2%). However, we documented some significant pathogens such as canine distemper virus (CDV) and metastrongyloid nematodes. Illegal killing was confirmed in 23 cases (6.6%). Of note, illegal killing is likely underestimated in this study, given that radio-collared lynx were found to be proportionally more often illegally killed than the unmonitored ones found by chance. Furthermore, most individuals were found to be affected at least by one non-specific, mild to moderate inflammatory process of unknown origin, such as interstitial pneumonia (n = 59) or interstitial nephritis (n = 25). Additionally, cardiac changes of variable severity were observed in 125 lynx, and severe soft tissue mineralization was detected in 10 individuals. The frequency of these findings warrants further investigation. Thus, this study confirms the importance of systemic post-mortem examination and general health surveillance of free-ranging Eurasian lynx in Switzerland, in support of translocation projects, conservation of the species, and to provide a better understanding of their pathologies.

Toxoplasmosis is a globally prevalent protozoan parasitic disease of livestock, among others, with significant zoonotic potential. This study aimed to assess the seroprevalence of Toxoplasma gondii antibodies in serum samples from water buffaloes (Bubalus bubalis) in Sohag governorate, Upper Egypt. In addition, several factors related to animals, management, and environment were analyzed to identify the risk factors for T. gondii infection. A cross-sectional epidemiological approach was employed, with samples collected from various locations across the region and tested using a commercially available indirect enzyme-linked immunosorbent assay (iELISA). Animal and environmental factors were evaluated to identify potential risk factors for the disease. The overall seroprevalence of T. gondii among the tested buffaloes was 7% (24/342). Seasonal variations were observed, with the highest seropositivity recorded in spring (10.7%; 11/103), followed by autumn (8%; 2/25), summer (5.6%; 7/125), and winter (2.2%; 2/89). High seropositivity was detected in aborted females, at 19% (4/21), and in repeated breeders, at 10.5% (4/38), in relation to buffaloes showing anestrus (no positive cases), although the differences were not statistically significant. Our findings suggest that T. gondii is endemic in Sohag, with water buffaloes serving as sentinel animals for the disease. The spring season appears to be a risk factor for infection. Further studies are needed to assess the potential risk to humans, particularly regarding the consumption of raw or undercooked buffalo meat infected with T. gondii.