“…Indeed, several populations have been identified as being colonized by the fungus. Low burden of P. jirovecii organisms have been detected using PCR assays in patients with various levels of immunodeficiency (Nevez et al, 1999a;Nevez et al, 1999b), with acute or chronic pulmonary diseases (Calderon et al, 1996;Armbruster et al, 1997;Sing et al, 1999b;Nevez et al, 2002), immunonaive infants with P. jirovecii primary infection (Nevez et al, 2001a, Vargas et al, 2001, pregnant women with physiological immunity changes (Vargas et al, 2003), and health care workers in contact with patients with PCP (Miller et al, 2001, Durand-Joly et al, 2003, reviewed in Peterson et al, 2005. In fact, Pneumocystis infections can have a large spectrum of presentations, of which PCP in immunocompromised patients may represent only a part, while mild infections such as colonization may constitute the major part.…”