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A 19-month study on the prevalence of fasciolosis in 30 naturally infected cows, the presence of infected and non-infected Lymnaea (Fossaria) humilis snails, and variation in soil temperature and humidity is reported. The prevalence of fasciolosis in cattle declined from around 50% in March to 30% in July, then, it increased from August, reaching a plateau of 100% in November-January, before gradually declining thereafter. A rise in soil humidity and temperature in June and July, respectively, which peaked between August and November was observed. In July, L. (F.) humilis snails appeared, but the infection could only be found in these in August and November. The number of infected snails did not reflect the infestation rate in cows, even though the infestation kinetics in both hosts behaved as predicted from the life cycle of the parasite.

The aims of this study were to determine the frequency of egg shedding (percentage of egg-positive faecal samples) and faecal egg counts (FEC) over 13 months in two different breeds of ewes, both pregnant and non-pregnant, in a mountainous region of central Mexico. Additionally, the effect of ivermectin and albendazole treatments on FEC reduction was recorded. The study also aimed to relate temperature and rainfall to FEC. The gastrointestinal nematode (GIN) third-stage larvae genera recovered from both faeces and grassland pastures in a temperate region were also assessed. Faecal samples were collected from ewes at monthly intervals for 13 months to investigate the FEC population of GIN larvae, their concentration and genera in grass samples collected from grazed and rested pastures. Egg-shedding frequency ranged from 0 to 92% and FEC from 0 to 12,000 eggs per g faeces (epg), with counts in Suffolk higher than in Dorset ewes. The identified genera were Haemonchus, Trichostrongylus, Teladorsagia, Cooperia, Oesophagostomum, Bunostomum, Nematodirus and Strongyloides. Haemonchus and Trichostrongylus were the most common genera. The number of L3 was higher in grazing lands than in those at rest. The highest FEC were recorded in the dry season due to peripartum, but the highest L3 counts were recorded in the rainy season. The coexistence of species of different geographical distributions at this site may be because there is a confluence of Nearctic and Neotropical geographic regions; thus, despite the temperate climate, tropical species can be found. Additionally, this study suggests that increasing temperatures could favour the presence of different tropical GIN species together with typical temperate-zone GIN species.

Leucine aminopeptidase (LAP) and cathepsin L1 (CL1) are important enzymes for the pathogenesis and physiology of Fasciola hepatica. These enzymes were analysed in silico to design a chimeric protein containing the most antigenic sequences of LAP (GenBank; AAV59016.1; amino acids 192-281) and CL1 (GenBank CAC12806.1; amino acids 173-309). The cloned 681-bp chimeric fragment (rFhLAP-CL1) contains 270 bp from LAP and 411 bp from CL1, comprising three epitopes, DGRVVHLKY (amino acids 54-62) from LAP, VTGYYTVHSGSEVELKNLV (amino acids 119-137) and YQSQTCLPF (amino acids 161-169) from CL1. The ~25 kDa rFhLAP-CL1 chimeric protein was expressed from the pET15b plasmid in the Rosetta (DE3) Escherichia coli strain. The chimeric protein rFhLAP-CL1, which showed antigenic and immunogenic properties, was recognized in Western blot assays using F. hepatica-positive bovine sera, and induced strong, specific antibody responses following immunization in rabbits. The newly generated chimeric protein may be used as a diagnostic tool for detection of antibodies against F. hepatica in bovine sera and as an immunogen to induce protection against bovine fasciolosis.