John Cutler is the researcher in question. He was a public health medical officer. His study was conducted for 2 years in the mid 40s. He exposed prostitutes that already had syphilis or gonorrhea to the Guatemalan prisoners.
There were around 1,500 subjects in this study, none of who were aware of the study or asked for their consent. During the study it was confirmed that syphilis is a sexually transmitted disease (STD). They also tried infecting the prisoners in other ways to see if the disease could be transmitted that way.
Syphilis is a sexually-transmitted infectious disease. The bacteria that cause it spread through broken skin or mucous membranes.
Pregnant mothers infected with the disease can pass it to the baby developing in their womb. This is called congenital syphilis.
Syphilis is widespread in the United States. It mainly affects sexually active adults ages 20 to 29.