How often should a patient be tested for BK virus and parvovirus B19 after kidney transplantation?

From the Guidelines

After kidney transplantation, BK virus screening should be conducted monthly for the first 3-6 months post-transplant, then every 3 months until the end of the first year, as recommended by the most recent and highest quality study 1. For Parvovirus B19, testing should be performed when clinically indicated, particularly if the patient develops unexplained anemia, as there is no standard screening protocol. BK virus monitoring is crucial because immunosuppressive medications can activate latent virus, potentially causing nephropathy and graft failure in 1-10% of kidney transplant recipients. Early detection allows for reduction of immunosuppression before significant kidney damage occurs. Parvovirus B19 testing is important when patients show signs of infection such as severe anemia, as this virus can persist in immunocompromised patients and cause chronic anemia. Both viruses require prompt management to prevent complications and preserve graft function.

The recommended screening protocol for BK virus is based on the KDIGO clinical practice guideline for the care of kidney transplant recipients, which suggests screening all kidney transplant recipients for BKV with quantitative plasma NAT at least monthly for the first 3-6 months after transplantation, then every 3 months until the end of the first post-transplant year, and whenever there is an unexplained rise in serum creatinine 1. This guideline also recommends reducing immunosuppressive medications when BKV plasma NAT is persistently greater than 10,000 copies/ml. In contrast, the American Society of Transplantation recommendations for screening, monitoring, and reporting of infectious complications in immunosuppression trials in recipients of organ transplantation suggest monitoring plasma or whole blood or urinary BK viral load at a minimum of once a month for 6 months, then at months 9 and 12 post-transplant 1. However, the KDIGO guideline is more recent and provides a more comprehensive approach to BK virus screening and management.

Some studies have highlighted the importance of monitoring for BK virus in kidney transplant recipients, particularly in the context of immunosuppression trials 1. However, these studies do not provide a clear recommendation for the frequency of BK virus screening. In contrast, the KDIGO guideline provides a clear and evidence-based recommendation for BK virus screening, which should be followed in clinical practice. Additionally, some studies have discussed the monitoring of other viruses, such as CMV, in immunosuppression trials 1, but this is not directly relevant to the question of BK virus and Parvovirus B19 screening in kidney transplant recipients.

Key points to consider in BK virus and Parvovirus B19 screening include:

• The importance of early detection and management of BK virus infection to prevent nephropathy and graft failure
• The need for regular screening for BK virus in the first year after kidney transplantation
• The importance of monitoring for Parvovirus B19 in patients with unexplained anemia
• The need for prompt management of both viruses to prevent complications and preserve graft function.

From the Research

Testing Frequency for BK Virus

• The frequency of testing for BK virus after kidney transplantation is crucial for early detection and management of the infection 2.
• A screening protocol consisting of BKV polymerase chain reaction testing in blood starting 2 months after kidney transplantation and every 2 months thereafter, continuing through month 24, is recommended 2.
• Additional screening for 6 more months is performed in patients who receive anti-lymphocyte globulin for the treatment of acute rejection 2.
• All patients with otherwise unexplained allograft dysfunction are also screened for BK virus 2.

Testing Frequency for Parvovirus B19

• Parvovirus B19 infection can occur at any time after kidney transplantation, with a median duration from transplant to development of anaemia of 6 weeks (range: 4-40 weeks) 3.
• There is no specific recommended frequency for testing parvovirus B19 after kidney transplantation, but a high index of suspicion is necessary for early diagnosis and management 4, 5, 3.
• Patients with anemia, leukopenia, or thrombocytopenia after kidney transplantation should be tested for parvovirus B19 infection 4, 5, 3.

Combined Testing Approach

• Both BK virus and parvovirus B19 infections can cause significant morbidity in kidney transplant recipients, and a combined testing approach may be necessary for early detection and management 2, 4, 6, 5, 3.
• The use of immune function assays, such as the ImmuKnow assay, may also be helpful in monitoring the immune status of kidney transplant recipients and detecting potential infections 6.