In clinical terms graft versus host disease (GVHD) is divided in two forms: it is a chronic form and acute form. Both are equally dangerous and caused by the same reasons of mismatch of immune cells of a person after they go through a transplant surgery.
The acute type of GVHD occurs about 100 days after the transplant surgery. It is a major challenge for transplant surgeons, because it has a higher mortality and morbidity rate. It is very difficult to manage.
On the other hand, chronic form of GVHD has adverse influence in the long-term survival of the person in the post-transplant time. It also occurs after about 100 days of the transplant surgery. It too is very difficult to manage and treat.
As such condition of the person suffering from either type of the GVHD is similar in the post-transplant era. They are basically two categories defined based on the subject and level of stem cells attack, while in both cases the attack is the main problem.
The definition of the two types also depend on the damage done to the persons vital organs, for example, kidneys and liver etc, after suffering from the problem. In the acute for example, the damage is quicker than other form.
GVHD occurring through blood transfusion is as severe as in case organs transplant. This the reason that blood is not transfused to a person with being irradiated, which means blood has to be treated before transfusion. The mismatching immune cells in the blood attack the same way the cells in the tissues of an organ do, and the level of damage is as quick and severe as it is in case of organs transplant.