Primary mycoses and virulence of dimorphous particularly dangerous micromycetes

Mycotic infections are traditionally considered to be markers of immunodeficiency, however, primary mycoses develop even in immunocompetent individuals. Etiological agents of primary mycoses, which, according to the nomenclature adopted in the Russian Federation, are classified as particularly dangerous, are micromycetes of group II pathogenicity of the genera Coccidioides, Histoplasma, Paracoccidioides, Blastomyces. Particularly dangerous mycoses are common in certain geographical areas of the world: coccidioidomycosis occurs in semi-desert regions, histoplasmosis and paracoccidioidomycosis – in tropical areas, and blastomycosis – in temperate climate regions. However, despite the endemic nature of these diseases, they remain important both for European countries and the Russian Federation for a number of reasons, sporadic cases of particularly dangerous mycoses are regularly recorded in many European countries. It has been shown that several genetically determined factors are important for the implementation of the virulent properties of pathogenic fungi. Thermal dimorphism is of fundamental importance as a trigger for the transformation of a pathogen from a mycelial to a tissue (parasitic) growth phase, in which the causative agent of infection is able to fully realize its virulent properties.