Well, at least in Nebraska, that's what the law says. Here it is:
42-102. Minimum age; affliction with venereal disease, disqualification.
At the time of the marriage the male must be of the age of seventeen years or upward, and the female of the age of seventeen years or upward. No person who is afflicted with a venereal disease shall marry in this state.
Okay, but is it enforced? Not according to the annotations (cases citing the statute).
Marriage of one afflicted with venereal disease is not void but voidable [the unknowing party can walk] Christensen v. Christensen, 144 Neb. 763, 14 N.W.2d 613 (1944).But ...
Where party afflicted with venereal disease enters into marriage with full knowledge thereof, such party is barred from seeking annulment. Christensen v. Christensen, 144 Neb. 763, 14 N.W.2d 613 (1944).And ...
If parties are of the age of consent, the marriage is valid, even though license was wrongfully obtained. Baker v. Baker, 112 Neb. 738, 200 N.W. 1003 (1924).