Abstract
Rabbits, infected with syphilis by intracutaneous injection of 300 or 30,000 Treponema pallidum, were given a single intramuscular injection of 20 mg/kg of Trobicin in water 4 days after the inoculation. There was a definite prolongation of the subclinical incubation period. If comparable effects occur in man, diagnosis and epidemiology of early syphilis will be more difficult when this drug is used.