This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'Which is false about syphilis - \nSelect and explain. \nA. TPI gives definite diagnosis, B. TPHA is earliest to be +ve, C. VDRL is +ve 1 week after appearance of chancre, D. Serologically not different from yaws', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., TPHA is earliest to be (+) ye About other options - TPI is a specific treponemal test and gives definite diagnosis. - VDRL test becomes positive 7-10 days after the appearance of primary chancre (3-5 weeks after acquiring the infection.) - All treponemal and nontreponemal serological tests may be positive in nonveneral treponematoses (eg yaws, pinta and endemic syphilis), so can not differentiate nonveneral treponematoses from syphilis.", 'role': 'assistant'}]