Prepatent RT-LAMP Detection of Fasciola gigantica in Snails (Lymnaea spp.) and Goats (Capra hircus) Targeting Cathepsin B3 gene

Cathepsins are cysteine proteases secreted in different stages of Fasciola species of flukes. Cathepsin B is predominantly found in eggs, metacercariae and the newly excysted juvenile (NEJ) stages of the fluke but not in adults. Cathepsin B3 was identified in F. gigantica NEJs that facilitates the migration of the excysted parasite to the liver. Here, RT-LAMP was utilized in the detection of F. gigantica during the prepatent period or the period between infection and the demonstration of the parasite i.e. from the egg to the NEJ stages. We investigated the feasibility of identifying the cathepsin B3 gene in various samples including snails, as the intermediate host, the plasma, sera and feces of goats as the definitive host animal targeting the Cathepsin B3 gene. Out of 90 snails, 61% were detected positive using RT-LAMP, 26% (32/122) in fecal samples, 4% (5/122) in sera and 70% (86/122) in plasma of the suspected infected goats. These findings provide further indication for early diagnosis of fasciolosis and a novel approach for the improved disease management and control.