So there are four possibilities.
1) He is too fragile from the beginning and dies quickly.
2) It is a little stronger is survival with disease without beating it, and is more fragile than another.
3) He can beat the disease and therefore should no longer have a symptom of this disease.
4) This is a real chimera.
A few questions.
1) If it is a real chimera in this case I am curious to know what is the chimeric factor producing this effect ?
2) What happens if grafting on another resistant subject ?
3) What happens if a resistant subject is grafted on it ?