MT-ND4 and pneumocystosis: CRISPR Nad4 assay results demonstrated high specificity for P. jirovecii infections in this study, suggesting that studies designed to detect P. jirovecii–specific RNA or DNA targets in minimally invasive or noninvasive diagnostic specimens from large, well-characterized cohorts could be used to evaluate transmission among close contacts, the incidence of PCP and P. jirovecii colonization, and its environmental prevalence (39, 40).