Can Fasciola hepatica modulate the severity of COVID–19?

Peru is considered a hyperendemic zone of fasciolosis with a prevalence between 6.7 and 47.7% (average 24.4%) in humans. In this area, the efficacy of Triclabendazole in cattle is only 25.2%, therefore the presence of resistant strains is widely distributed. The problem is accentuated by being a zoonotic disease. In addition, Triclabendazole is the only effective drug against the different forms of the parasite. Cathepsins L and B are involved in the migration, nutrition, reproduction, and evasion of the immune response and survival of Fasciola hepatica. When analyzing the process in which the SARS–CoV–2 virus enters the cell, the presence of cellular transmembrane serine protease 2 (TMPRSS2) and Cathepsin L/B (CTSL) is required; where TMPRSS2 activates viral S–glycoprotein to fuse the cell with the viral membrane, whereas viral S–glycoprotein is activated by CTSL, allowing viral and endosomal membrane fusion, virus infecting the host cell is of concern to estimate the possible effect that it could generate in populations infected with F. hepatica because an existing coinfection is needed, as a result of the systemic increase of the Cathepsins L/B secreted by this parasite and the survival within the definitive host, possibly these populations are become more susceptible to viral infection by co–infection with the parasite; calling on the scientific community to identify parasite control alternatives and not have an associated problem in the short term.