Why can sexually transmitted infections continue to spread when early symptoms are mild or absent?

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sexually transmitted disease Scanning electron micrograph of the spirochete *Treponema pallidum* attached to testicular cell membranes.

Sexually transmitted infections (STIs) often continue to spread because many of these diseases do not produce significant initial symptoms. Because individuals may be unaware they are infected due to the absence or mildness of early signs, they often do not seek treatment.1

This lack of diagnosis and subsequent lack of treatment allows the infections to persist, increasing the likelihood of transmission to others and raising the risk of serious long-term health complications, such as female sterility in the case of untreated chlamydial infections. Consequently, the health-care community emphasizes safer sexual practices, such as the use of condoms or abstinence, as a primary strategy to stem the transmission of these diseases.1