A positive Mantoux test suggests the client has:

A positive Mantoux test indicates that the individual has been exposed to Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). The test measures the immune response to a small amount of purified protein derivative (PPD) from the TB bacteria. When a person has been infected with TB, their immune system mounts a response, and this is reflected as induration (a raised area) at the site of the test, typically appearing 48 to 72 hours after administration.

Importantly, a positive Mantoux test does not confirm whether the individual has active tuberculosis disease; rather, it indicates that exposure has occurred at some point. This could be a past infection that was successfully contained by the immune system, which is why it's crucial to follow up with additional evaluations (like a chest X-ray or sputum tests) if active disease is suspected.

In this context, other choices focus on different aspects of TB or immunity that do not accurately reflect the implications of a positive Mantoux test. The test does not confirm active disease, nor does it suggest resistance or passive immunity. Each of these would require different mechanisms and evidence, distinguishing them from the simple exposure indicated by the Mantoux test result.