Microbiology Practice Exam 2026 - Free Microbiology Practice Questions and Study Guide

Transmission of syphilis occurs primarily during the primary and secondary stages of the infection. In the primary stage, the presence of a chancre, which is a sore at the site of infection, is a key factor as it is highly infectious. The sore contains a large number of Treponema pallidum bacteria, the causative agent of syphilis, making contact with it a direct route for transmission.

During the secondary stage, the transmission continues to be possible due to the systemic spread of the bacteria. This stage is characterized by widespread rash and mucous membrane lesions, which can also harbor the bacteria, facilitating transmission through direct contact.

In contrast, during the tertiary stage, which can occur years after the initial infection if left untreated, the Treponema pallidum is no longer present in infectious lesions. Instead, the symptoms at this stage are more related to complications from the disease, such as gummas or damage to organs and tissues, rather than contagious lesions.

Understanding these stages is crucial for both preventing transmission and implementing effective public health strategies to control the spread of syphilis.