Short answer. Yes, where the disease existed at the time of the marriage and is found to be serious and apparently incurable. Concealment is not required for this ground, which is what separates it from the fraud route, though a concealed infection can support that separate ground instead.
What the law says
(6) That either party was afflicted with a sexually-transmissible disease found to be serious and appears to be incurable.
Family Code, Article 45 — Grounds for Annulment. Read the full provision →
Three elements, and knowledge is not one of them
The clause requires that the party was afflicted with a sexually-transmissible disease, that the disease is found to be serious, and that it appears to be incurable, all measured as of the time of the marriage. Notice what is absent. Nothing turns on whether the affected spouse knew, hid it, or was themselves unaware. The ground rests on the condition itself rather than on any deceit, which is why an infection disclosed honestly before the wedding can still fall within it if the three elements are met.
Serious and incurable are the limits
The two qualifiers do most of the filtering. A transmissible infection that responds to ordinary treatment does not satisfy the clause, because it is neither serious in the sense intended nor incurable. The statute also uses the softer word appears for incurability, which acknowledges that medicine deals in prognosis rather than certainty. What the court is being asked for is a medical finding on gravity and prospects, not a moral judgment about how the infection was acquired.
The overlap with the fraud ground
The same facts often engage a second, separate route. Concealment of a sexually transmissible disease existing at the time of the marriage is one of the circumstances the Family Code treats as fraud, and there the disease need not be serious or incurable, because the wrong being addressed is the concealment. So a spouse deceived about a treatable infection may have a case under fraud but not under this clause, while a spouse who knew of a grave and incurable one may have this clause but not fraud. Which theory fits your facts is a question worth resolving before anything is filed.
What to secure, and how quickly
The case is proved with medical evidence, so what matters is documentation of diagnosis and of timing: test results, treatment records and any clinical history capable of placing the condition before the wedding rather than after it. If the fraud theory is in play, keep also whatever shows what you were told and when you learned the truth. Both routes carry prescriptive periods, and the fraud clock in particular can begin running from discovery. Take the records to a lawyer promptly rather than waiting for the situation at home to resolve itself.