PneumocystisInfection: Seeing beyond the Tip of the Iceberg

Pneumocystis jirovecii probably is one of the more frequent infectious agents faced by humans in everyday life. However, after the first description of Pneumocystis a hundred years ago, the organism was largely ignored until the dramatic increase in the incidence of Pneumocystis pneumonia (PCP) that occurred with the emergence of the human immunodeficiency virus (HIV) pandemic, which made pneumocystosis a major medical and public health problem in the 1980s [1]. The AIDS epidemic stimulated research on PCP that can be considered just the tip of the iceberg of human Pneumocystis infection [2]. Research interest in Pneumocystis infection accompanied the clinical interest but was thwarted by the inability to culture the organism in vitro. However, the introduction of experimental models and molecular biology techniques have allowed us to overcome some of the limitations imposed by the lack of a reliable culture system [1]. The past 20 years has seen impressive