AdvertisementRecord High Number Of STD Infections In U.S., As Prevention Funding DeclinesAugust 28, 2018Richard HarrisfacebookEmailA tinted transmission electron micrograph of Chlamydia trachomatis bacteria (light purple/black) inside a cell. Chlamydia is the most common sexually transmitted disease in the U.S., with more than 1.7 million reported cases in 2017. (Biomedical Imaging Unit, Southampton General Hospital/Science Source)