The first new algorithm for Lyme disease testing in 25 years ditches Western immunoblot in favor of a two-enzyme immunoassay test sequence. Elitza Theel, Ph.D., director of the Mayo Clinic Infectious Diseases Serology Laboratory, outlined the advantages of the new strategy in CAP Today.
The standard algorithm—enzyme immunoassay and a confirmatory Western immunoblot—has several weaknesses. "Its sensitivity in the early stage of Lyme disease is pretty poor, reported as about 40% to 60%," Dr. Theel says. "The immunoblot test can also be challenging for some laboratories to implement."
Following the development of improved enzyme-linked immunosorbent assays, or ELISAs, the CDC last year approved the new algorithm—which uses a second ELISA instead of a Western blot. Dr. Theel notes that the new algorithm is more sensitive in early disease stages and sidesteps Western blots' limitations.
Western blot sometimes generates false-positive results. In addition, although many reference labs now process blot testing automatically, some labs continue to interpret immunoblot bands visually. "That comes with quite a bit of subjectivity and variability in interpretation," Dr. Theel says. "Also, for smaller hospital labs that send their blot testing to commercial labs, the turnaround time to results is significantly longer."
Because interpretation of Lyme disease testing has always been challenging, the CDC and the Association of Public Health Laboratories, as well as a number of reference labs, have formed a Lyme disease serology working group. Dr. Theel, a member of the CAP Microbiology Committee, participates in the working group's efforts to assemble a document outlining how to interpret Lyme disease testing results.
"We hope to provide recommended, standardized language for laboratories to use in reporting Lyme disease serologic results," she says. "I think this will be very helpful as laboratories roll out the modified two-tiered algorithm."