Researchers reveal how the parasite Fasciola causes neurological disorders

Fascioliasis is a parasitic disease caused by two species present in the liver: hepatic fasciola, spread all over the world, and Fasciola gigantica, which is in Asia and Africa. The high pathogenicity of this disease has led the World Health Organization (WHO) to include it in the list of major diseases of humanity. Both species of Fasciola cause a variety of clinical conditions, from symptomless cases to severe symptoms that can lead to death. Among the severe cases, there is a wide range of neurological diseases, including limb paralysis, motor and speech disorders, loss of sense, seizures, epilepsy and coma. Spain is the second country in the world with the highest number of neurological fascioliasis cases diagnosed after France.

In an article published in the journal Parasitology, Maria Adela Valero and María Dolores Bargues, professors in the Department of Pharmacy and Techniques of Pharmacy and UV Parasitology, as well as Professor Santiago Mas-Coma and his collaborators, show that Fasciola excretes and / or secretes a large number of Protein transformation of a plasma protein called plasminogen into plasmin enzyme, able to break down clots or thrombi. This transformation of plasminogen into plasmin is part of the fibrinolytic and contact systems whose final product is a powerful proinflammatory peptide called bradykinin, which increases the vasodilatation of arteries and veins and vascular permeability.

This is how Fasciola ends up generating bradykinin capable of opening the blood-brain barrier, a small layer of impermeable cells that protects the brain. This barrier is located in the capillaries that irrigate the brain and acts as a filter between the blood and the nervous system, blocking the pbadage of a large number of substances from the blood to the brain. The opening of the blood brain barrier by bradykinin allows different products of secretion / excretion of Fasciola to access the brain, as well as other toxic substances derived from the action pathogen of this parasite, with the resulting neurological effects.

Santiago Mas-Coma, expert on tropical diseases at WHO and director of the study, said: "One of the main problems of these patients with neurological symptoms is that specialist doctors who have These patients rarely think of fascioliasis as a source, because of the fact that it took us many years of work because no one had any idea of ​​the pathways that a parasite present in the patients' liver could have. the teams had already considered, but they had not been confirmed Clarify how the parasite is at the origin of these diseases and explain all the complexity and clinical heterogeneity of these cases is undoubtedly the most important challenge. "

María Adela states: "There are inherent problems with the experimental part needed to obtain the fresh biological material to extract and properly badyze the excretion / secretion proteins in a transmission parasite. vector via a freshwater snail, and the subsequent experimental infection.These are long experiences where many aspects can go wrong.Hope we had the desired success. "