Mycobacterium tuberculosis transmission and HIV status.

Clinical and pathological findings in tuberculosis developing in HIV-positive patients with a relative conserved immune status (represented by CD4+ T-cell count) are virtually indistinguishable from those seen in tuberculosis in HIV-negative individuals. However, by contrast, knowledge of tuberculosis acquired in non-HIV individuals may not apply to the most severely immuno-suppressed AIDS patients, in whom the clinical and pathological picture is often atypical. Opinions differ on the infectious potential of these patients. Pulmonary evidence of a greater than usual number of viable bacilli interspersed in poorly competent and unspecific tissue reactions3 suggested a potential for greater infectiousness. In some hospital settings transmission of M tuberculosis infection and disease from AIDS patients to health-care workers was significantly more likely than in comparable HIV-negative settings.4 On the other hand, the immunodeficiency-related tendency to a higher bacillary count seems to be counterbalanced by a lower ability to generate open lesions (the ones accounting for infectiousness) in the respiratory tract