Pneumocystis jirovecii and pneumocystosis

Abstract

Pneumocystis jirovecii pneumonia (PcP or pneumocystosis) remains a major cause of respiratory illness among immunocompromised patients, especially those infected with the human immunodeficiency virus (HIV). P. jirovecii infection has also been detected in healthy individuals and people with chronic lung diseases, raising the possibility that the spectrum of illness caused by this pathogenic fungus may extend well beyond the immunocompromised host. In industrialized countries, while the number of acquired immunodeficiency syndrome (AIDS) patients suffering from PcP decreases, there is a rising number of non-HIV immunocompromised patients at risk for life-threatening PcP. In contrast, in developing countries a limited number of epidemiological studies have evaluated PcP prevalence; however, recent reports have described an increased rate of the disease in AIDS patients in Africa, Asia and South America. After nearly three decades of intensive research, a significant progress has been made in the understanding of PcP; however, this disease continues to be a challenge for clinicians and microbiologists; in particular, the processes of detection and interpretation of the PcP testing, because even the most current diagnostic methods cannot adequately differentiate between colonized (asymptomatic) and symptomatic patients.