DOI:
ABSTRACT
The median infective dose of Treponema pallidum subsp. pallidum and the production of immunity to reinfection in C4D guinea pigs have been determined with 10(1) to 10(6) organisms per infective dose. The mean infective dose is 10(2) organisms, and immunity--in those animals that demonstrated lesions--developed after 4.5 months postinfection.
