To intrude into the deeper regions of the lungs, the bacteria that cause tuberculosis appear to mask their identity and hitch a ride on white blood cells.
The findings suggest an explanation for the longstanding observation that tuberculosis infections begin in the comparatively sterile lower lungs. In the upper respiratory tract, resident microbes and inhaled microbes of a variety of species signal their presence.
These tip-offs alert and attract many infection-fighting cells to the upper airways. The presence of other microbes in the upper airway may thereby help to keep TB infections at bay by creating a hostile environment.
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