In bone marrow transplants, toxoplasma infection is uncommon but if it occurs it appears to be a result of reactivation of infection rather than infection acquired from the donor. This is quite separate from renal, cardiac, and cardiac and lung transplants, where the toxoplasma infection usually results from transplantation of an infected organ into an individual who is susceptible to toxoplasma infection. It can be important that those bone marrow transplant patients who have evidence of past infection are given prophylaxis post transplant. Therefore, it is important that the test for immunity is done with a specific test.

• Some commercial screening tests may not be sensitive or specific enough to identify patients who are immune to toxoplasma infection. In bone marrow transplant patients, therefore, it is important to use reliable tests in order to be confident that immunity is genuine. However, the cost/benefit ratio of a routine toxoplasma screen for bone marrow transplant patients needs to be assessed in the light of local epidemiology.
• In countries with a high prevalence of toxoplasma infection, there are more individuals with long standing infection, therefore in such countries as France, reactivation of infection is a more serious problem than in Britain.