 Tertiary syphilis may occur approximately 3 to 15 years after the initial infection , and may be divided into three different forms : gummatous syphilis ( 15 % ) , late neurosyphilis ( 6 @.@ 5 % ) , and cardiovascular syphilis ( 10 % ) . Without treatment , a third of infected people develop tertiary disease . People with tertiary syphilis are not infectious . 
