KSHV Complications Rising in Organ Transplant Recipients

A new CDC report is raising a question transplant physicians don't love answering: why isn't a virus that can cause cancer part of routine organ donor screening?

The report, published in the March 5, 2026 issue of MMWR, looked at Kaposi sarcoma–associated herpesvirus, known as KSHV or human herpesvirus 8. It found that suspected donor-derived KSHV infections in transplant recipients rose roughly fivefold over five years.

What KSHV Actually Is

KSHV causes Kaposi sarcoma, a cancer of the blood vessel walls that shows up as purple, brown, or reddish skin lesions and can also affect internal organs. It's also linked to certain lymph node disorders and a serious inflammatory condition called Kaposi sarcoma–associated herpesvirus inflammatory cytokine syndrome, or KICS for short. That's a mouthful, so think of KICS as the body's immune system overreacting in a dangerous, systemic way once KSHV takes hold.

In people with healthy immune systems, KSHV infection often causes no problems at all and can sit dormant for years. The risk climbs sharply when someone's immune system is suppressed, which is exactly the situation every organ transplant recipient is in by design, since immunosuppressant drugs are what keep the body from rejecting the new organ.

The Numbers From the MMWR Report

Between January 2021 and September 2025, the CDC identified 46 deceased organ donors whose transplanted organs were suspected of transmitting KSHV. That compares to just 9 such donors flagged during the entire 2016 to 2020 period. Those 46 donors' organs, 185 of them, went to 153 transplant recipients.

Here's the number that stands out: as of February 2026, 74 of those 153 recipients, or 48%, had developed a confirmed posttransplant KSHV infection. That's nearly one in two.

Most of the donors and recipients involved were HIV-negative. About two-thirds of the flagged donors had a documented history of nonmedical drug use, either inhaled or injected, which the report's authors note as a relevant risk factor worth flagging during donor evaluation, even though it isn't currently part of formal screening criteria.

The Screening Gap Behind This

Here's the part that actually explains the headline. In the U.S., organ donors are routinely tested for HIV, hepatitis B and C, CMV, EBV, syphilis, and HTLV before their organs are approved for transplant. KSHV is not on that standard list.

That gap matters because, without routine testing, a donor's KSHV status often isn't known until a recipient starts showing symptoms months later. In this cohort, the retrospective testing that was eventually done on the 46 flagged donors found 25 (54%) tested positive for KSHV after the fact, 4 tested negative, and 17 were never tested at all. So even after a problem was suspected, more than a third of the donors involved were never actually confirmed either way.

The median time between transplantation and a recipient's first clinical signs of KSHV disease was 208 days, just under seven months. That's a long enough gap that a treating doctor who wasn't specifically thinking about KSHV could easily attribute new symptoms to something else entirely.

In clinical practice, this kind of delayed-onset, low-suspicion diagnosis is exactly where problems get missed. A transplant recipient presenting seven months out with vague symptoms and unusual skin findings isn't an obvious KSHV case unless the treating team is actively keeping it on their differential. The MMWR authors make almost exactly this point, calling for a higher baseline level of suspicion among clinicians managing transplant patients.

What This Means If You or a Family Member Has Had a Transplant

This isn't a reason to panic if you or someone you love received an organ transplant. KSHV-related disease, while serious, remains uncommon relative to the total number of transplants performed each year in the U.S., over 22,000 annually.

What it does mean is that new or unusual skin lesions, unexplained fevers, or swollen lymph nodes appearing months after a transplant deserve a prompt conversation with your transplant team rather than being written off. If something feels off and you can't immediately get in with your transplant specialist, starting with a general physician to get things checked and appropriately referred is a reasonable first step. Diagnostic confirmation typically involves blood or tissue testing, which a diagnostic center can help coordinate alongside your treating hospital.

For anything that feels urgent, particularly rapid symptom progression, don't wait for a scheduled follow-up. Go through your hospital's transplant or infectious disease team directly.