A Kidney Transplant Came With an Unwelcome Hitchhiker: A Deadly Tick Germ

A person’s precious organ donation came with an unexpected visitor. In a new paper out this month, scientists have documented an unconventional way of catching a rare germ normally spread by ticks: from a person’s infected donated kidney.

Doctors and health officials detailed the unusual mishap in a report published Monday in the journal Emerging Infectious Diseases. Both the living donor and recipient became sick soon after their operations, leading doctors to discover that the former had transmitted an infection caused by Ehrlichia bacteria. Fortunately, the tainted transfer was detected in time and both patients were treated successfully.

Ticks are prolific carriers of many germs, including the germs behind Lyme disease, relapsing fever, and ehrlichiosis. Several species of bacteria cause ehrlichiosis, though most cases are tied to Ehrlichia chaffeensis. The disease is rarely documented, though cases have been increasing over time. In 2022, there were 1,570 reported cases of ehrlichiosis compared to 201 cases in 2000, when the disease first became nationally tracked. But this most recent case is even rarer than usual.

According to the report authors, the donor was a 33-year-old man from Minnesota who agreed to donate his kidney to an unrelated recipient. He had no obvious red flags, passing all the typical screening tests, which include looking for infections that could be dangerous if passed onto a transplant recipient. His recipient was a 24-year-old man with end-stage kidney disease from Wisconsin.

Both men’s operations went smoothly. But on the same day after his kidney was removed, the donor developed a rash on his left hip and leg along with muscle pain and weakness. Doctors diagnosed him with rhabdomyolysis, a condition where muscle tissue rapidly breaks down and releases proteins that damage organs, particularly the kidney. Doctors stabilized him quickly, and he recovered well enough to be discharged six days after the operation.

The recipient, meanwhile, appeared fine at first. But a week after the transplant, he was admitted to the hospital with fever, joint pain, and fluid build-up around his kidneys. Given the man’s other symptoms, including a low platelet count, the doctors tested him for various tickborne germs, which eventually confirmed the presence of E. chaffeensis bacteria. He was given a new course of antibiotics standard for these infections and eventually recovered as well.

All ehrlichiosis cases in the U.S. must be reported to state health agencies. The recipient’s organ transplantation, coupled with the fact that he had no other risk factor for ehrlichiosis (such as traveling recently to tick-laden parts of the U.S.), prompted a wider investigation by health officials in both Wisconsin and Minnesota.

Eventually, they discovered that the donor had traveled to Kansas for a hunting trip a month before his operation, and that he had to remove several ticks from his clothing and body while there. He also felt sick a week before the transplant, though he attributed it to simple food poisoning. Other tests found evidence of the bacteria in the donor and in the transplanted kidney.

“The laboratory evidence, exposure history, and epidemiology of ehrlichiosis strongly support donor-derived transmission of E. chaffeensis initially acquired by the donor through a tick bite in Kansas 3 weeks before donation,” the authors wrote.

Transplanted cases of ehrlichiosis are exceedingly rare, but not unheard of—and they can be deadly. A 2021 paper, for instance, detailed two deaths likely caused by ehrlichiosis caught from a single deceased donor’s kidneys in 2020. The typical fatality rate is around 1%, though roughly 60% of patients still get hospitalized as a result. But ehrlichiosis and other infections are generally more dangerous for transplant recipients, since they have to take immune-suppressing drugs to avoid organ rejection.

Given how rare this disease is, the doctors say it wouldn’t be justified to routinely screen for it in donors. But transplant doctors should keep an eye out for the potential risk posed by ehrlichiosis and other germs normally spread by ticks. “In summary, clinicians should remain vigilant for tickborne infections in potential organ donors, particularly those with known exposure to common disease vectors,” they wrote.