Transplants may spread infectious agents, such as lethal brain-damaging amoebas

By Janet Raloff

Web edition: September 24, 2010

Sometimes organ donors can unwittingly share a toxic bonus, according to a new case report by the Centers for Disease Control and Prevention. It described the spread of a lethal protozoan from donated tissues into the brains of transplant recipients.

Three weeks after receiving her new kidney, a 31 year old woman developed headaches, numbness, neck spasms, leg twitching and more. She was treated at the local hospital on December 10, 2009, then sent home with muscle relaxants — only to return two days later after having passed out at home. In the emergency room, the woman suffered a major seizure. She was admitted into an intensive-care unit and shortly thereafter physicians took an MRI scan of her head. It showed “numerous ring-enhancing lesions” throughout her brain.

A biopsy two days later confirmed the presence of amoebas in her brain. Despite extensive treatment with six drugs, the woman's condition continued to deteriorate. Within two and a half months of her transplant surgery she was dead.

Other patients received a kidney, heart and liver from the same donor, a 4-year-old boy. He had died from encephalitis — an inflammation of the brain — about two and a half weeks after being hospitalized with fever and seizures. When physicians were unable to find another source of his encephalitis, the boy's symptoms were attributed to flu, which he had.

However, as recipients of his organs began developing seizures within a few weeks of their transplant surgeries, CDC pathologists began probing the donor’s brain. And they found it riddled with Balamuthia mandrillaris, amoebas that naturally infect soil.

Extensive drug treatment saved the other organ recipients’ lives, although the second kidney-transplant patient still suffers from paralysis in one arm, muscle weakness in both legs and intermittent vision loss.

This was the first report of Balamuthia transmission from organ transplants. However, on August 27 CDC confirmed a second cluster of Balamuthia infections among patients that got transplants from another donor. Reference to both incidents appears in the September 17 Morbidity and Mortality Weekly Report, a CDC publication.

Because these soil microbes are ubiquitous, the report suggests that the true incidence of this potentially lethal amoebic disease may be underreported owing to its misdiagnosis as other neurological problems.

Organ donors are screened for common infectious agents, but not relatively rare ones like this amoeba. CDC now recommends that physicians and organ-donation networks consider the possibility of Balamuthia infection whenever they encounter potential donors with puzzling encephalitis.