This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Tabes dorsalis is seen in: 
Select and explain. 
A. Primary syphilis, B. Secondary syphilis, C. Tertiary syphilis, D. Latent syphilis
C: Tertiary syphilis
Answer: C: Tertiary syphilis 
Explanation: Ans. is 'c' i.e., Tertiary syphilisRef:Harrison, 19th/e, p. 1132; Ananthanarayan, 9th/e, p. 370Tabes dorsalis, also known as syphilitic myelopathy, is a slow degeneration (specifically, demyelination) of the nerves primarily in the dorsal columns (posterior columns) of the spinal cord (the portion closest to the back of the body). These nerves normally help maintain a person's sense of position (proprioception), vibration and discriminative touch.Tabes dorsalis is caused by demyelination caused by advanced syphilis infection (tertiary syphilis), when the primary infection by the causative spirochete bacterium Treponema pallidum is left untreated for an extended period of time (past the point of blood infection by the organism).