Epidemiology of Pneumocystis infection in Human

• Published in: Journal de mycologie médicale 2009-12, Vol.19 (4), p.270-275
• Main Author: CALDERON, E. J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Colonisation; Colonization; Epidemiology; Fundamental and applied biological sciences. Psychology; Human immunodeficiency virus; Infectious diseases; Medical sciences; Microbiology; Miscellaneous; Mycology; Mycoses; Pathogenicity, host-agent relations, miscellaneous strains, epidemiology; Pneumocystis; Transmission; Épidémiologie
• ISSN: 1156-5233; 1773-0449
• DOI: 10.1016/j.mycmed.2009.08.001

Pneumocystis jirovecii ( P.  jirovecii) is an atypical fungus that causes pneumonia in immunosuppressed individuals and significant questions about its epidemiology and transmission remain unanswered. It is widely accepted that animal sources of P.  jirovecii can be excluded because the Pneumocystis organisms that infect mammalian species are characterized by strong, close host species specificity. Similarly, an environmental reservoir of infection has not been found. Airborne transmission has been demonstrated in animal models and is assumed among humans. Highly sensitive PCR-technologies have allowed the detection of low numbers of Pneumocystis organisms in respiratory samples from colonized individuals who do not have Pneumocystis pneumonia. Studies have shown that individuals who have underlying Human immunodeficiency virus (HIV)-infection or other types of immunosuppression and those who are not immunosuppressed but have a chronic lung disease are often colonized by P.  jirovecii. Further hypotheses claim that these groups may play a role in person-to-person transmission and that they may serve as reservoirs for future Pneumocystis infection in other susceptible individuals. On the other hand, P.  jirovecii DNA was recently identified by molecular techniques in 35% of foetal lung and 5% of placenta samples from nonimmunodepressed women, who had a miscarriage, evidencing transplacental transmission in humans. Vertical transmission of P.  jirovecii in humans could be an additional route of transmission of this stenoxenic microorganism that would ensure the persistence of Pneumocystis independent of environmental hazards. However, further studies are needed to confirm the role of this transmission route in the epidemiology of Pneumocystis infection in humans. Pneumocystis jirovecii ( P.  jirovecii) est un champignon atypique responsable de pneumonie chez les sujets immunodéprimés. Des questions significatives sur l’épidémiologie et la transmission demeurent sans réponse. On accepte en général que les animaux ne constituent pas une source d’infection pour l’homme car les Pneumocystis des divers mammifères présentent une très étroite spécificité d’hôte. Similairement, il n’y a pas d’évidence d’un réservoir environnemental. La transmission aérienne a été démontrée chez les modèles animaux et l’on suppose qu’elle existe aussi dans les populations humaines. Des techniques PCR hautement sensibles ont permis de détecter des faibles taux de Pneumocystis dans des