What is the difference between a sexually transmitted infection (STI) and sexually transmitted disease (STD)?
These terms are often confused, but they are not interchangeable. Sexually transmitted infection is the broadest term. All STDs are STIs, but not all STIs are STDs. (To keep with the trends in modern health care, we will be using the label “STI” where previously you would have expected to see “STD” in discussing this topic.) A sexually transmitted infection is an invasion of and multiplication in bodily tissue by a microorganism (for example, bacterium, virus, protozoan) that is usually (more than half the time) passed from one person to another during intimate bodily contact meant to give or derive sexual gratification. A sexually transmitted disease, on the other hand, involves manifest damage to the body with or without symptoms secondary to an infection that is usually (more than half the time) passed from one person to another during intimate bodily contact meant to give or derive sexual gratification.
