Current epidemiology of Pneumocystis jirovecii infections.

: Pneumocystis fungi has been recognized as causative agent of pneumonia in immunocompromised individuals. The epidemiology of Pneumocystis infection has been dynamically changing over the past two decades. In this review, the current understanding of factors contributing to the spreading of Pneumocystis jirovecii in immunocompetent and immunocompromised human populations is highlighted. Primary infections, routs of transmission and colonization issues are discussed. Data concerning P. jirovecii infections in Poland is also presented.