Answer: Islam is a religion which commands its followers to be truthful and honest and hence, in the case of marriage this is also required. In the mentioned situation, one must be truthful to the person in whom there is an interest of marriage. He must be very truthful to the person and let the present state be known. Concealing information in this case will be totally haram. If after knowing the state of a person who is suffering from the disease mentioned, a person wants to be married then there is no prohibition in this marriage. It will not be permissible for a Muslim male to conceal such information in order to get married. It must be understood however, that if a marriage has taken place and the infected person knows that by having sexual relations the spouse can contract the disease, then it would be impermissible for him to have sexual relations with her.

And Allah knows best.
Mufti Waseem Khan