Sexually transmissible infections in scientific literature have been called venereal diseases from the 19th century to the mid-20th century, with a focus primarily on syphilis and gonorrhoea, which was narrow and carried stigma, to sexually transmitted diseases by the mid-1970s as more infections were recognised and later to sexually transmitted infections (STIs) in the 1990s to include cases without symptoms and use clearer, less stigmatising language.
STIs are usually defined as diseases transmitted mainly through sex. However, many can also be transmitted in other ways, such as through blood, from mother to child or through close contact. This is the case with Treponema pallidum, hepatitis B virus (HBV), mpox (monkeypox) virus and human papillomavirus (HPV), which complicate the clarity and consistency of the STI label. For example, T. pallidum is typically transmitted through sexual contact but can also be acquired via blood transfusion