A Measurement Model to Quantify Systemic Bacilli Load in Severe HIV-Associated Tuberculosis.

Pathogen load is considered fundamental to infection pathobiology but is unobserved or inadequately measured. We used latent variable modeling to characterize HIV-associated tuberculosis mycobacterial load in 519 inpatients. Tests on urine and blood, not sputum, showed substantial covariance. Summarizing covariance via measurement models estimated pathogen loads with stronger correlation with host inflammation and mortality than traditional measures such as blood culture time to positivity.