There is no clear answer, as the decision would depend on the medical evidence presented, the tests conducted and kind of TB detected. Just merely stating that having active TB leads to inadmissibility is incorrect.
See
Fung v. Canada (Minister of Employment & Immigration)
1986 CarswellNat 219, 18 Admin. L.R. 260, 37 A.C.W.S. (2d) 312, 4 F.T.R. 118
This decision may not be available on CanLII, but the relevant part states:
"When the applicant Gun Sui Fung attended for the medical examination required by the Canadian immigration officials and was diagnosed as having tuberculosis, he was told that he could undergo a 1-year course of treatment and he complied. Simple justice required not only that the course of treatment be given the opportunity to run its full course, but that there be not even the appearance of failure to consider the results of that full course of treatment in assessing his application. The treatment began in July of 1982 and yet a final determination adverse to the applicant was made in March of 1983. In reaching the decision to refuse the application, the respondents, in my opinion, treated Gun Sui Fung unfairly and were in fundamental error in failing to allow the specified treatment to run its course and to give adequte consideration to the results of the completed course of treatment in assessing his application. These circumstances warrant an order of certiorari setting aside the decision to refuse and a direction that the application be reconsidered on the basis of an analysis of the results of the full course of treatment recommended by Dr. Duchastel and carried out at the Canton city clinic. The applicants shall have their costs of this application."
Further, s. 19(1)(a)(i) of the IRPA does not allow landing to applicants who are "likely to be a danger" on health grounds. However, when an applicant is already in Canada, when he is diagnosed with a medical condition which may make him inadmissible, but is undergoing treatment, the entire medical evidence has to be looked into before making a decision.
I am not contending that it would be a straight forward case, but the fact that he has already been reported and is undergoing treatments, would be considered before a decision is made. I am also not aware of what the applicant's status is in Canada, whether he underwent a medical before coming to Canada, and many other questions need to be answered.