Final answer:
A red-brown rash on the palms and soles is typical for secondary syphilis, which is a serious STI caused by Treponema pallidum.
Step-by-step explanation:
A red-brown rash on the palms of the hands and soles of the feet is typically a symptom of secondary syphilis. This stage of the infection is characterized by skin rashes that can appear on various parts of the body, including the palms and soles. The rash may be accompanied by other symptoms such as malaise, fever, and swollen lymph nodes. Syphilis is a serious sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. If left untreated, it can progress to more severe stages and lead to significant health complications.