A study from St. Jude Children’s Research Hospital suggests that a noninvasive blood test can detect infections in childhood leukemia patients days before symptoms appear.1 Earlier treatments could lead to increased cure rates.

The Karius test from Karius, Redwood City, Calif, is a noninvasive blood test using DNA sequencing and artificial intelligence to detect more than 1,400 bacteria, fungi, parasites, and viruses.

“Parents of children with cancer often wish they had a crystal ball to know what’s coming next, and this new study is showing promising signs we may have found one for them,” says cosenior author Joshua Wolf, MD, PhD, an associate faculty member in the St. Jude department of infectious diseases. “Infections are the leading cause of death for children treated for leukemia in the United States. This work is going right to the heart of detecting new infections before symptoms appear, and that is nothing short of a game-changer in how we treat and combat deadly infections in children with cancer.”

Patients treated with chemotherapy for cancers such as leukemia have weakened immune systems and are vulnerable to life-threatening infections. Some children with leukemia have a higher chance of dying from an infection than from the cancer itself. Currently, prophylactic antibiotics are used in certain high-risk patients to try to prevent infections. However, this approach is effective only half of the time, and exposure to antibiotics may cause gastrointestinal symptoms or contribute to antibiotic resistance.

The Karius test was originally developed to detect the specific causative pathogens of complicated pneumonia, cardiovascular infections, and infections in immunocompromised patients. The St. Jude study marks the first time the test has been used to detect and identify infections among pediatric leukemia patients.

The study enrolled 47 patients, 12 of whom developed a total of 19 bloodstream infections. The microbial cell-free DNA test performed by Karius predicted the bloodstream infections in 75% of cases as long as 3 days before patients showed symptoms. The researchers are conducting an expansion of the study to analyze the test’s ability to detect infection in more patients.

For more information, visit St. Jude Children’s Research Hospital.


1. Goggin KP, Gonzalez-Pena V, Inaba Y, et al. Evaluation of plasma microbial cell-free DNA sequencing to predict bloodstream infection in pediatric patients with relapsed or refractory cancer. JAMA Oncol. Epub ahead of print, December 19, 2019; doi: 10.1001/jamaoncol.2019.4120.

Featured image: Joshua Wolf, MD, PhD, Courtesy St. Jude Children’s Research Hospital.