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Published on: February 23, 2014
Transmission and Colonization of Pneumocystis jirovecii
Cristian Vera1, Zulma Vanessa Rueda2
1Grupo de Investigación en Salud Pública, Research Department, Facultad de Medicina, Universidad Pontificia Bolivariana, Medellín 050031, Colombia.
Abstract:
Pneumocystis spp. was discovered in 1909 and was classified as a fungus in 1988. The species that infects humans is called P. jirovecii and important characteristics of its genome have recently been discovered. Important advances have been made to understand P. jirovecii, including aspects of its biology, evolution, lifecycle, and pathogenesis; it is now considered that the main route of transmission is airborne and that the infectious form is the asci (cyst), but it is unclear whether there is transmission by direct contact or droplet spread. On the other hand, P. jirovecii has been detected in respiratory secretions of hosts without causing disease, which has been termed asymptomatic carrier status or colonization (frequency in immunocompetent patients: 0-65%, pregnancy: 15.5%, children: 0-100%, HIV-positive patients: 20-69%, cystic fibrosis: 1-22%, and COPD: 16-55%). This article briefly describes the history of its discovery and the nomenclature of Pneumocystis spp., recently uncovered characteristics of its genome, and what research has been done on the transmission and colonization of P. jirovecii. Based on the literature, the authors of this review propose a hypothetical natural history of P. jirovecii infection in humans.
Insights
Pneumocystis jirovecii, a fungus, is transmitted airborne and can colonize hosts asymptomatically. Recent genomic discoveries shed light on its biology, transmission, and a hypothetical natural history of human infection.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Genomics
Background:
- Pneumocystis jirovecii, a fungal pathogen, was discovered in 1909 and classified in 1988.
- Recent genomic studies have revealed key characteristics of P. jirovecii.
- Understanding its biology, evolution, lifecycle, and pathogenesis is crucial for public health.
Purpose of the Study:
- To review the history, nomenclature, and genomic characteristics of Pneumocystis spp.
- To summarize current research on P. jirovecii transmission and colonization.
- To propose a hypothetical natural history of P. jirovecii infection in humans.
Main Methods:
- Literature review of Pneumocystis spp. discovery and classification.
- Analysis of recent genomic findings for P. jirovecii.
- Synthesis of research on P. jirovecii transmission routes and asymptomatic colonization.
Main Results:
- The primary transmission route for P. jirovecii is airborne, with the cyst (asci) being the infectious form.
- Asymptomatic colonization by P. jirovecii occurs across diverse populations, including immunocompetent individuals, pregnant women, children, and patients with HIV, cystic fibrosis, or COPD.
- Recent genomic data provide new insights into the fungus's biology and evolution.
Conclusions:
- P. jirovecii infection presents a complex natural history, including asymptomatic colonization.
- Airborne transmission is the established route, though direct contact and droplet spread require further investigation.
- This review proposes a hypothetical model for P. jirovecii's lifecycle and infection progression in humans.
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