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.

Vaccination with cathepsin L mimotopes of Fasciola hepatica in goats reduces worm burden, morphometric measurements, and reproductive structures.

Fasciolosis is a worldwide emergent zoonotic disease that significantly constrains the productivity of livestock. We conducted an experimental trial with four groups of five goats each, vaccinated with 1 × 1013 phage particles of cathepsin L1 (CLI: DPWWLKQ), CL1 (SGTFLFS), and CL2 (PPIRNGK) mimotopes combined with Quil A adjuvant. Animals received a booster four weeks later. The control group received phosphate-buffered saline. All animals were infected with 200 Fasciola hepatica metacercariae at week six and euthanised 16 weeks later. The percentage of significant worm reduction in CL1 (DPWWLKQ), CL1 (SGTFLFS), and CL2 (PPIRNGK) compared to the control group were 55.40%, 70.42% (P < 0.05), and 32.39%, respectively. Vaccinated animals showed a significant reduction in faecal egg production and egg viability. A significant reduction in the total biomass of parasites recovered was observed in the CL1 (DPWWLKQ) and CL1 (SGTFLFS) groups. In goats vaccinated with CL2 (PPIRNGK), fluke length and width were smaller than those in the control group. Furthermore, animals receiving CL mimotopes showed a significant reduction in the total area of reproductive structures. Goats immunised with phage-displayed mimotopes produced significantly high titres of specific IgG1 and IgG2 isotypes, indicating a mixed Th1/Th2 response. The liver fluke burdens in goats vaccinated with CL1 (DPWWLKQ) and CL1 (SGTFLFS) were significantly correlated with IgG and IgG1 levels.

Cathepsin L1 mimotopes with adjuvant Quil A induces a Th1/Th2 immune response and confers significant protection against Fasciola hepatica infection in goats.

Thirty goats were randomly allocated in five groups of six animals each, for immunization with 1 × 10(14) phage particles of clones 11, 13, and 13 with Quil A adjuvant and wild-type M13KE phage at the beginning and 4 weeks later. The control group received phosphate-buffered saline. All groups were challenged with 200 metacercariae at week 6 and slaughtered 14 weeks later. The mean worm burdens after challenge were reduced by 46.91% and 79.53% in goats vaccinated with clones 13 and 13 with Quil A (P < 0.05), respectively; no effect was observed in animals immunized with clone 11 and M13KE phage. Animals receiving clones 11, 13, and 13 with Quil A showed a significant reduction in eggs output. Vaccinated animals produced parasite-specific total IgG antibody which were boosted after challenge with metacercariae of F. hepatica. Furthermore, levels of anti-phage total IgG increased rapidly within 2 weeks of the first vaccination and were always significantly higher in all vaccinated goats than in the infected control group. The fluke burden of goats immunized with clones 13 and 13 with Quil A was significantly correlated with IgG2 and total IgG. Goats vaccinated with phage clones produced significantly high titres of IgG1 and IgG2 antibodies indicating a mixed Th1/Th2 response. These data indicate that cathepsin L1 mimotopes has a potential as a vaccine candidate against Fasciola hepatica, whose efficacy will be evaluated in other host species, including those of veterinary importance.