Researchers Develop First Multiplex Test for Tick-Borne Disease Detection

Researchers have developed the first multiplex array for diagnosis of tickborne diseases, according to a study published online Feb. 16 in Nature Scientific Reports. The TBD-Serochip can differentially diagnose eight tickborne infections, including Lyme disease.

FDA Approves 1st Test to Screen Blood For Tick- Borne Babesia Disease

In early March, the U.S. Food and Drug Administration approved two donor screening tests to detect Babesia, the tick-borne parasite responsible for babesiosis infections. The tests—Imugen Babesia microti Arrayed Fluorescent Immunoassay, for the detection of antibodies to Babesia microti (B. microti) in human plasma samples, and the Imugen Babesia microti Nucleic Acid Test, for the detection of B. microti DNA in human whole blood samples—are “in-house tests” performed by Oxford Immunotec (Norwood, Mass.).

Experts estimate that there are up to 2,000 cases of babesiosis reported in the U.S. each year, with the majority transmitted from deer ticks in states in the Northeast and upper Midwest. However, babesia can also be transmitted by transfusion of blood or blood components from an infected donor and is a “concern.” It is the most frequently reported transfusion-transmitted parasitic infection in the United States, according to the U.S. Centers for Disease Control and Prevention.

The FDA said that investigational use of Babesia donor testing has been in place since August 2012 under investigational new drug applications and has resulted in the removal of “a significant number of infected units” from the blood supply. However, the two tests were granted priority review. The FDA is expected to soon release a draft guidance for testing donor samples for Babesia.

It has been estimated that approximately 3 million clinical specimens are tested for tick-borne diseases each year, with serology being the primary method of diagnosis Testing includes use of enzyme-linked immunosorbent assay, indirect immunofluorescent assay, and western blot assays. But, experts say, diagnosis is hampered by varying degrees of test accuracy in the early phase of disease, the need for specialized laboratories, lack of testing standardization, and cross-reactivity between infectious agents.

“The reported incidence of tick-borne disease has risen continuously over the past three decades,” write the authors led by Rafal Tokarz, from Columbia University in New York. “Nonetheless, the true incidence of tick-borne diseases is likely greatly underestimated, as patients with presumed tick-borne diseases are rarely tested for the full range of tick-borne agents, and only a fraction of positive cases are properly reported. New diagnostic assays that can detect infections with the full range of TBD agents are urgently needed.”

In the February report, researchers from Columbia University unveiled the TBD-Serochip, which consists of 12 subarrays, each able to simultaneously test for the presence of antibodies in blood using more than 170,000 protein fragments.

The authors say the multiplex assay offers many benefits over current serial testing, including:

• Screening for multiple agents simultaneously

• Enhancing the likelihood of antibody detection in early disease states

• Detecting and confirming infection simultaneously

“Because peptides are programmed for synthesis in situ, the array composition can be continuously and inexpensively modified based on performance or the need to address new immunological targets,” writes Tokarz and colleagues.

Takeaway: Progress is being made in the detection of tick-borne disease both in clinical patient samples and in the U.S. blood supply.