The potential aetiologies of infection are diverse and can often progress rapidly in transplant patients. Many challenges exist in the prevention, diagnosis, clinical consequences, and management of infectious disease in transplant recipients with emerging issues, including donor-derived infection, the impact of pandemic influenza on the SOT recipient, and drug-resistant infections.

In the first month post-transplant, there are two major causes of infection in all forms of solid organ transplantation: pre-existing infection from either the donor or recipient and infectious complications of the transplant surgery and hospitalisation.

After the first month of the post-transplant period, the effect of immunosuppression is often maximal, and patients are at greatest risk for the development of opportunistic infections.

Timely and accurate monitoring of viral load through a molecular test is essential for transplant patients.

The various clinical utilities of viral load testing in post-transplant patients are prognostication in terms of disease risk and severity, prevention in terms of guidance in the initiation and duration of preemptive therapy, diagnosis and treatment in terms of efficacy,duration, risk of relapse, and risk of antiviral resistance.

While the quantification of viruses that cause important infections in transplant recipients has been the standard of care for years, important challenges related to standardisation remain.

The issues are wide-ranging, and until they are adequately addressed, the full impact of viral load testing regarding clinical management decisions will not be realized. This video focuses on a broad array of problems, including the lack of available FDA-approved or cleared tests, limited uptake of international standards, accurate quantification of secondary standards, specific assay characteristics, and commutability.

These factors, taken together, greatly influence the clinical utility of testing. For example, it has not been possible to define thresholds that predict the risk of developing disease and determine significant changes in serial viral load values for a given patient. Moreover, the utility of international guidelines may be limited due to the lack of a standardised assay.

While great strides in the development of international standards and the widespread adoption of transplant viral load testing have been made over the past decade, much remains to be done.

Adoption of international standards has been slow; there is limited data on commutability for most assays and viruses, and LDTs make up the vast majority of assays used to quantify these viruses. Moving forward, it is essential that standardised, sample-to-answer commercial tests become more widely available for the common transplant viruses.

These factors, taken together, greatly influence the clinical utility of testing. For example, it has not been possible to define thresholds that predict the risk of developing disease and determine significant changes in serial viral load values for a given patient. Moreover, the utility of international guidelines may be limited due to the lack of a standardised assay.