Lyme disease: impact of the CDC surveillance criteria on patients

Townsend Letter for Doctors and Patients, June, 2004 by Marcus A. Cohen

From its studies, the College of American Pathologists concluded that commercially available ELISAs yield too many false positives and false negatives (they are not sensitive enough), and therefore they should not be used as an initial serologic screen in the CDC's two-step testing for antibodies to Lyme. (4)

Concerns About the CDC's Interpretation of Western Blots

When the CDC revised its surveillance criteria in Dearborn, Michigan in 1996, it selected five of ten Western blot bands for IgG and two of three bands for IgM as indicative of Lyme disease. IgM bands help diagnose Lyme in the early acute stage, IgG bands help in later stages. ("IgG" stands for "Immunoglobulin G," a class of antibodies commonly circulating in blood and especially active against bacteria, proteins foreign to the body, and viruses. "IgM" are antibodies of high molecular weight, appearing early in the immune response, replaced by lower weight IgG antibodies.)

Note: The CDC chose for diagnostic purposes the bands most frequently found to be positive in early Lyme on test results in patients with EM.

The CDC redefinition included bands 31kd and 34kd, for outer surface proteins A and B (OspA, OspB) respectively, which are very specific for Lyme pathogen and therefore significant in detecting the disease. It included one band, 41kd, a common antigen for flagella-bearing microorganisms.

Dr. Nick Harris, an expert on Western blots, was invited to serve on a committee at the Dearborn conference. Reaching him by phone at his lab in California, I asked for a sound-byte opinion of the conference. "It was billed," he said, "as a consensus meeting. But it was a consensus meeting only in the sense that the participants were expected to consent to revisions of the CDC surveillance criteria previously decided in closed session."

He then faxed me a paper he published in 1998, titled, "An Understanding of Laboratory Testing for Lyme Disease." (5) It gives much more than a byteful about the CDC revisions. I'm sharing several passages here, reserving a larger discussion with Dr. Harris on the drawbacks of serologic tests in Lyme for a more suitable time:

"If the intention were only for public health surveillance and reporting of disease, these changes would not have caused a problem. Unfortunately, these recommendations became the standard in most areas and especially with insurance companies. That was unfortunate because the Dearborn meeting was not supposed to be about setting national standards for Lyme disease diagnosis; rather it was to be a discussion regarding the Western blot during early Lyme disease....

"The criteria for a positive Western blot to B. burgdorferi ... are very conservative and require 5 to 10 antibody bands for IgG positivity; the original recommendations do not even recognize equivocal or borderline results if less than five bands are detected. The cut-off assumes that all Lyme patients have similar immune systems. They ignore the diversity of the immune response seen in other diseases....