CD4 and HIV infectious disease: CD4 counts were not systematically collected in stage 1 of the STREAM trial, but we did not find a significant association between HIV and locations of lung parenchymal opacities, extent of opacities, the presence of cavitation, location of cavitation, costophrenic obliteration, and pleural thickening, which may be because those participants who had HIV infection were likely to have had relatively high CD4 counts.