Pneumocystis jirovecii causes pneumonia in immunosuppressed individuals. However, it has been reported the detection of low levels of Pneumocystis DNA in patients without signs and symptoms of pneumonia, which likely represents colonization. Several studies performed in animals models and in humans have demonstrated that Pneumocystis induces a local and a systemic response in the host. Since P. jirovecii colonization has been found in patients with chronic pulmonary diseases it has been suggested that P. jirovecii may play a role in the physiopathology and progression of those diseases. In this report we revise P. jirovecii colonization in different chronic pulmonary diseases such us, chronic obstructive pulmonary disease, interstitial lung diseases, cystic fibrosis and lung cancer.

We aimed to describe Pneumocystis jirovecii pneumonia (PCP) prevalence and features in children from sub-Saharan Africa and to investigate PCP-associated risk factors. During 2006-2007 we used molecular methods to test children younger than 5 years old admitted with severe pneumonia to a hospital in southern Mozambique for Pneumocystis infection. We recruited 834 children. PCP prevalence was 6.8% and HIV prevalence was 25.7%. The in-hospital and delayed mortality were significantly higher among children with PCP (20.8% vs. 10.2%, p 0.021, and 11.5% vs. 3.6%, p 0.044, respectively). Clinical features were mostly overlapping between the two groups. Independent risk factors for PCP were age less than a year (odds ratio (OR) 6.34, 95% confidence interval (CI) 1.86-21.65), HIV infection (OR 2.99, 95% CI 1.16-7.70), grunting (OR 2.64, 95% CI 1.04-6.73) and digital clubbing (OR 10.75, 95% CI 1.21-95.56). PCP is a common and life-threatening cause of severe pneumonia in Mozambican children. Mother-to-child HIV transmission prevention should be strengthened. Better diagnostic tools are needed.