The demonstration of spirochetes in syphilitic blood.
D000293:Adolescent; D000328:Adult; D000818:Animals; D005060:Europe; D005260:Female; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D008251:Macaca; D008297:Male; D011247:Pregnancy; D013144:Spirochaetales; D013587:Syphilis / Q000097:blood / Q000266:history* / Q000382:microbiology / Q000635:transmission