“ETHICALLY IMPOSSIBLE” STD Research in Guatemala from 1946-1948 
rectum - the portion of the intestine between the colon and the anus. 
salvarsan - an arsenic-based compound used in the treatment of syphilis. 
serological — having to do with blood serum, particularly with regards to its 
reactions and properties. 
serologists - scientists who specialize in the reactions and properties of blood 
serum. 
seronegative - having a negative serum reaction, particularly with regard to 
a test for a particular antibody. 
seropositive - having a positive result from a serological test for a disease, in 
this case syphilis. 
serum - a clear fluid that is left over from blood plasma after clotting factors 
(such as fibrinogen) have been removed through the process of clot formation. 
sexually transmitted diseases (STDs) - diseases that are spread through 
sexual contact (vaginal, oral, or anal). 
silver proteinate - the active ingredient in one of the post-exposure prophy- 
laxis regimens used for gonorrhea. 
spirochetal - caused by or consisting of spirochetes. 
spirochete - a spiral-shaped bacterium. Syphilis is among the diseases caused 
by spirochetes. 
submucosal - introduced beneath a mucous membrane. 
sulfonamide compounds (including sulfanilamide and sulfathiazole) 
- an early antimicrobial drug used to treat gonorrhea before the advent of 
penicillin. 
sulcus (or coronal) of the penis - a groove in the surface of the penis, 
super-infect - to infect with an additional strain of a disease already present, 
symptomatic - having symptoms associated with a disease. 
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