Every year in the United States, more than 22,000 people receive organ transplants — kidneys, livers, hearts, lungs, and pancreases from deceased donors. The organ matching and screening process is among the most rigorously regulated procedures in American medicine. Donors are tested for HIV, hepatitis B and C, CMV, EBV, syphilis, HTLV, and other pathogens before their organs are cleared for transplantation. One virus is conspicuously absent from that list: Kaposi Sarcoma-Associated Herpesvirus (KSHV), also known as Human Herpesvirus 8 (HHV-8).
And according to a landmark CDC MMWR investigation published March 5, 2026, that screening gap is producing a growing patient safety crisis. Between January 2021 and September 2025, 46 cases of suspected donor-derived KSHV infection were identified among solid organ transplant recipients in the United States — approximately five times the rate documented during 2016–2020, when only 9 cases were reported in a comparable period. In the entire period from 2010 to 2025, 57 cases have been reported — meaning the majority of all cases ever documented in the United States occurred in just the past four years.
The clinical consequences are severe. KSHV is the causative agent of Kaposi sarcoma — a cancer of the blood vessel walls that produces characteristic purple, brown, or red lesions on the skin and can involve internal organs — as well as multicentric Castleman disease, a rare lymph node disorder, and KSHV Inflammatory Cytokine Syndrome (KICS), a life-threatening systemic inflammatory condition. In immunocompetent individuals, KSHV typically produces a mild or clinically silent infection that remains latent. In solid organ transplant recipients, who receive immunosuppressive medications to prevent rejection, KSHV can reactivate or proliferate from donor-transmitted virus to produce life-threatening disease.
Who the Donors Were — and Why the Pattern Matters
The MMWR investigation identified two-thirds of implicated donors as KSHV-positive HIV-negative individuals — a finding that challenges a common clinical assumption that KSHV in the United States is primarily associated with HIV infection or with men who have sex with men. Two-thirds of donors in this analysis had a documented history of nonmedical inhalation or injection drug use, which the investigators note may contribute to elevated KSHV transmission risk, though this association may be confounded by other factors.
The median interval from transplantation to initial clinical manifestation was 208 days — approximately seven months. This extended incubation period means that transplant recipients who develop Kaposi sarcoma or related conditions months after their transplant may not immediately trigger a link to a donor-derived infection in clinical practice. The delay also means that investigations must reach back through transplant records, organ matching records, and donor histories to establish the transmission connection.
The fact that routine screening of deceased organ donors for KSHV is not performed in the United States is the core policy problem that this investigation illuminates. Without pre-transplant donor KSHV testing, transplant centers cannot counsel recipients about KSHV risk before transplantation, cannot make organ acceptance decisions based on donor KSHV status, and cannot implement enhanced post-transplant surveillance in recipients who received organs from KSHV-positive donors.
What Transplant Recipients and Their Physicians Should Know
The investigators recommend that clinicians caring for organ transplant recipients maintain a high level of clinical suspicion for KSHV infection and promptly report suspected cases to transplant program coordinators and to the CDC. Recipients who develop skin lesions — particularly purplish or brownish lesions — unexplained lymphadenopathy, systemic inflammatory symptoms, or any pathology consistent with Kaposi sarcoma or lymphoproliferative disorder should be evaluated for KSHV.
For transplant programs, the MMWR investigation supports implementation of voluntary KSHV screening protocols for deceased donors and recipient counseling where feasible. Policy discussions about whether KSHV should be added to the standard donor screening panel are ongoing and are expected to be informed directly by this MMWR report.
Frequently Asked Questions
Q: What is KSHV and why is it dangerous for transplant recipients?
A: KSHV (Kaposi Sarcoma-Associated Herpesvirus/HHV-8) causes Kaposi sarcoma, multicentric Castleman disease, and KSHV Inflammatory Cytokine Syndrome — conditions that can be life-threatening in immunosuppressed transplant recipients.
Q: How much has donor-derived KSHV transmission increased?
A: The MMWR documents 46 cases in 2021–2025 compared to 9 in 2016–2020 — approximately a fivefold increase in the rate of donor-derived KSHV infections among US transplant recipients.
Q: Why are donors not routinely screened for KSHV?
A: KSHV is not currently included in the standard deceased organ donor screening panel in the United States. This is a recognized gap that the MMWR investigation and transplant medicine community are actively discussing.
Q: Who were the implicated donors?
A: Two-thirds were HIV-negative. Two-thirds had a history of nonmedical inhalation or injection drug use. The MMWR notes that KSHV in the US is not exclusively associated with HIV or sexual risk networks.
Q: How long after transplant do KSHV-related complications typically appear?
A: The median interval from transplantation to first clinical manifestation was 208 days — about 7 months. This delay can make it harder to connect the disease to donor transmission without proactive investigation.
