Evaluation of Reproductive Histology Response of Adult Fasciola hepatica in Goats Vaccinated with Cathepsin L Phage-Exposed Mimotopes.

Fasciolosis, a globally re-emerging zoonotic disease, is mostly caused by the parasitic infection with Fasciola hepatica, often known as the liver fluke. This disease has a considerable impact on livestock productivity. This study aimed to evaluate the fluke burdens and faecal egg counts in goats that were administered phage clones of cathepsin L mimotopes and then infected with F. hepatica metacercariae. Additionally, the impact of vaccination on the histology of the reproductive system, specifically related to egg generation in adult parasites, was examined. A total of twenty-four goats, which were raised in sheds, were divided into four groups consisting of six animals each. These groups were randomly assigned. The goats were then subjected to two rounds of vaccination. Each vaccination involved the administration of 1 × 1013 phage particles containing specific mimotopes for cathepsin L2 (group 1: PPIRNGK), cathepsin L1 (group 2: DPWWLKQ), and cathepsin L1 (group 3: SGTFLFS). The immunisations were carried out on weeks 0 and 4, and the Quil A adjuvant was used in combination with the mimotopes. The control group was administered phosphate-buffered saline (PBS) (group 4). At week 6, all groups were orally infected with 200 metacercariae of F. hepatica. At week 22 following the initial immunisation, the subjects were euthanised, and adult F. hepatica specimens were retrieved from the bile ducts and liver tissue, and subsequently quantified. The specimens underwent whole-mount histology for the examination of the reproductive system, including the testis, ovary, vitellaria, Mehlis' gland, and uterus. The mean fluke burdens following the challenge were seen to decrease by 50.4%, 62.2%, and 75.3% (p < 0.05) in goats that received vaccinations containing cathepsin L2 PPIRNGK, cathepsin L1 DPWWLKQ, and cathepsin L1 SGTFLFS, respectively. Animals that received vaccination exhibited a significant reduction in the production of parasite eggs. The levels of IgG1 and IgG2 isotypes in vaccinated goats were significantly higher than in the control group, indicating that protection is associated with the induction of a mixed Th1/Th2 immune response. The administration of cathepsin L to goats exhibits a modest level of efficacy in inducing histological impairment in the reproductive organs of liver flukes, resulting in a reduction in egg output.

Fasciolosis prevalence, risk factors and economic losses due to bovine liver condemnation in abattoirs in Mexico.

This study investigated the prevalence of bovine liver condemnation due to Fasciola hepatica in abattoirs and its influence on livestock productivity. It also explored risk factors such as season, breed, age and sex in the states of Puebla and Veracruz, Mexico. A total of 5281 cattle livers were inspected in two abattoirs. The overall prevalence of the parasite in cattle throughout 2020 was 24.9% (1313 out of 5281). The highest prevalence was found in Veracruz (28.5%; tropical climate), followed by Puebla (18.4%; temperate climate). The prevalence of fluke infection during the wet season was 19.0% and 25.8% in the states of Puebla and Veracruz, respectively; during the dry season, this was 18.0% and 30.2% respectively. The annual loss caused by condemnation of the liver for both abattoirs was estimated to be US$7502. Using multivariate logistic regression analysis, two models were constructed for potential association with the prevalence of condemned livers, using season, breed, age and sex as risk factors. The results indicate that season, age and sex were significantly associated with an increased risk of parasitic infection. Cattle age was the variable most strongly associated with F. hepatica infection, with the highest prevalence in cattle over three years of age as compared to younger animals, both in the states of Veracruz with a tropical climate (OR 6.443; 95% CI: 4.487-9.251) and in Puebla with a temperate climate (OR 2.854; 95% CI: 1.531-5.321). The results indicate that different factors were significantly associated with the prevalence of condemned livers, and it highlights the importance of continuous monitoring programmes for F. hepatica infection and preventing economic losses in cattle production.