Final answer:
The chronic infection caused by Treponema pallidum is syphilis, a sexually transmitted infection that can lead to serious health issues if untreated.
Step-by-step explanation:
The chronic infection caused by Treponema pallidum is syphilis. Syphilis is a sexually transmitted infection (STI) that can have severe long-term effects if left untreated. Treponema pallidum is a gram-negative spirochete responsible for this disease, which can cause significant tissue damage and systemic effects in the host. Treponemal serologic tests are used to diagnose syphilis, as they measure antibodies directed against Treponema pallidum. It's important to begin treatment as early as possible to prevent long-term complications and the spread of the infection.