Infectious agents including COVID-19 and the involvement of blood coagulation and fibrinolysis. A narrative review.

Marongiu, F; Grandone, E; Scano, A; Orrù, G; Marongiu, S; Gerosa, C; Fanni, D; Faa, G; Barcellona, D

OBJECTIVE Platelets, blood coagulation along with fibrinolysis are greatly involved in the pathophysiology of infectious diseases induced by bacteria, parasites and virus. This phenomenon is not surprising since both the innate immunity and the hemostatic systems are two ancestral mechanisms which closely cooperate favoring host's defense against foreign invaders. However, the excessive response of these systems may be dangerous for the host itself. MATERIALS AND METHODS We searched and retrieved the articles, using the following electronic database: MedLine and Embase. We limited our search to articles published in English, but no restrictions in terms of article type, publication year, and geography were adopted. RESULTS The hemostatic phenotype of the infectious diseases is variable depending on the points of attack of the different involved pathogens. Infectious diseases which show a prothrombotic phenotype are bacterial sepsis, SARS-CoV-2 and malaria. However, among the bacterial sepsis, Yersinia Pestis is characterized by a profibrinolytic behavior. On the contrary, the hemorrhagic fevers, due to Dengue and Ebola virus, mainly exploit the activation of fibrinolysis secondary to a huge endothelial damage which can release a large amount of t-PA in the early phase of the diseases. CONCLUSIONS Blood coagulation and fibrinolysis are greatly activated based on the strategy of the different infectious agents which exploit the excess of response of both systems to achieve the greatest possible virulence.