NEJM: March 26, 2026 – Volume 394, Issue 12

March 26, 2026 Ananya Mittal - World Editor

The New England Journal of Medicine this week publishes findings detailing probable transmission of Japanese encephalitis virus (JEV) through organ transplantation, raising questions about donor screening protocols and the potential for undetected spread. The report, appearing in the March 26, 2026 issue (Volume 394, Issue 12, pages 1240-1243), describes a cluster of cases in recipients who received organs from a single donor.

Understanding Japanese Encephalitis Virus

Japanese encephalitis is a mosquito-borne viral infection primarily affecting rural areas of Asia and the Western Pacific. While many infections are asymptomatic, JEV can cause severe neurological disease, including encephalitis (inflammation of the brain), leading to long-term disability or death. The virus is maintained in a cycle involving mosquitoes, pigs, and humans. There is a safe and effective vaccine available, but This proves not routinely administered in most Western countries due to the low risk of exposure. The World Health Organization provides comprehensive information on the disease, its transmission, and prevention.

The Recent Cluster: What the Evidence Shows

The cases detailed in the NEJM report involved three organ transplant recipients who developed neurological symptoms consistent with JEV infection within weeks of receiving organs from the same donor. The donor, who died from a stroke, had no known history of travel to endemic areas and had not been vaccinated against JEV. Testing of the donor’s tissues confirmed the presence of the virus. This suggests the donor had an asymptomatic or very mild infection at the time of death, which was not detected through standard donor screening procedures. The report highlights the challenges of identifying asymptomatic carriers of infectious diseases and the potential for transmission through organ transplantation.

The investigation involved detailed clinical assessments of the recipients, virological testing of donor tissues and recipient samples, and epidemiological investigation to trace potential sources of infection. The authors acknowledge the limitations of the study, including the small sample size and the difficulty in definitively establishing causality. While the evidence strongly suggests JEV transmission through the transplanted organs, other potential sources of infection cannot be entirely ruled out. Further research is needed to determine the prevalence of asymptomatic JEV infection in potential organ donors and to evaluate the effectiveness of enhanced screening measures.

Donor Screening and Emerging Risks

Current donor screening protocols typically focus on detecting infections with known risks of transmission through transplantation, such as HIV, hepatitis B, and hepatitis C. JEV is not routinely screened for, as it was previously considered a low-risk pathogen in most regions where organ transplantation is common. This case series underscores the need to reassess these protocols in light of changing epidemiological patterns and the increasing globalization of travel and trade. The possibility of undetected asymptomatic infections highlights the inherent limitations of relying solely on symptom-based screening.

The Centers for Disease Control and Prevention (CDC) offers guidance on JEV, including information for travelers and healthcare professionals. However, specific recommendations regarding donor screening are still under review following these recent findings. The CDC is collaborating with transplant centers and public health agencies to develop strategies for mitigating the risk of JEV transmission.

What Does This Mean for Transplant Recipients?

For organ transplant recipients, this news may understandably raise concerns. It’s vital to remember that this is a rare event, and the risk of JEV transmission through transplantation remains very low. However, recipients who have recently undergone transplantation and are experiencing neurological symptoms should promptly consult with their transplant team. Early diagnosis and supportive care are crucial for managing JEV infection.

The symptoms of JEV infection can be non-specific, including fever, headache, and stiff neck. As the disease progresses, more severe symptoms such as seizures, coma, and paralysis may develop. It’s important to differentiate these symptoms from those associated with immunosuppression, which is a common side effect of transplantation.

Public Health Implications and Next Steps

This cluster of cases has prompted a review of organ donor screening practices by national and international health authorities. The focus is on evaluating the feasibility and cost-effectiveness of incorporating JEV testing into routine donor screening panels. This may involve the development of new diagnostic assays and the implementation of surveillance systems to monitor the prevalence of JEV infection in potential donors.

Several key areas are under consideration:

  • Enhanced Surveillance: Strengthening surveillance systems to detect asymptomatic JEV infections in potential donors.
  • Diagnostic Testing: Developing and validating sensitive and specific diagnostic tests for JEV in donor tissues.
  • Risk Assessment: Refining risk assessment models to identify donors at higher risk of JEV infection based on travel history, exposure to mosquitoes, and other factors.
  • Vaccination Strategies: Exploring the potential for vaccinating organ donors against JEV in endemic areas.

The NEJM report serves as a critical reminder of the evolving landscape of infectious disease threats and the importance of ongoing vigilance in protecting the safety of organ transplantation. The process of updating guidance and implementing new screening measures will likely involve collaboration between transplant centers, public health agencies, and regulatory bodies. Continued monitoring and research will be essential to refine these strategies and minimize the risk of future JEV transmission through organ transplantation. The New England Journal of Medicine will continue to publish updates as new information becomes available.