Spring has arrived, and with it, the beginning of camping and hiking season. However, something as simple as a walk in the woods can mean exposure to deer ticks, some of which carry dangerous bacteria -- and a controversial CDC recommendation against a lab test for Lyme disease may mean that many infected individuals go undiagnosed and untreated.
Commonly known as Lyme disease for the town in Connecticut whose citizens were among the first to be identified as suffering from this ailment, Borrelia burgdorferi is the most common tick-borne illness in the United States. Roughly 20,000 cases of B. burgdorferi infections are diagnosed each year, and 20 percent of these patients will continue to experience persistent symptoms known as "chronic Lyme disease." Some researchers believe that the actual number of human Lyme cases is even greater -- as many as 300,000 new cases per year, most of which go undiagnosed by currently approved testing.
One problem that can lead to persistent symptoms is delay in diagnosis and treatment. Early symptoms of Lyme disease include flu-like fever, chills, and ache, as well as a rash known as erythema migrans (EM). The rash is often described as having a "bull's-eye" appearance, but some patients (such as Discover magazine's Pamela Weintraub, who spoke at a recent IOM meeting) report that doctors' rigid adherence to a narrow definition of the rash as a diagnostic marker has cost them crucial treatment time. The CDC recommends a two-tier test for Lyme disease involving an FDA-approved enzyme-linked immunosorbent assay (ELISA) followed (if necessary) by an FDA-approved immunoblot ("Western" blot).
However, some research scientists have used a process called "xenodiagnosis" to detect spirochetes up to three months after treatment with antibiotics such as ceftriaxone or doxycycline. Xenodiagnosis is the practice of exposing healthy organism to potentially infected tissue from another organism and then examining it for evidence of infection after an incubation period. Work in animal models indicates that "low levels [of non-cultivable spirochetes] could persist [...] after antibiotic treatment for disseminated B. burgdorferi infection."
Much of the current controversy about Lyme disease centers on the question of whether chronic B. burgdorferi infection exists, and if so, whether this chronic infection is responsible for hosts' neurological and joint-related symptoms. In 2012, Dr. Linda Bockenstedt and her colleagues at the Yale University School of Medicine studied Myd88-/- mice (mice with a particular genetic variant) that they infected with B. burgdorferi and then treated with antibiotics. Nine weeks after the completion of antibiotic therapy, spirochetes were not detected in the mice either by xenodiagnosis or by culture. However, the scientists did detect B. burgdorferi DNA in the knees of these mice.
Dr. Bockenstedt and her team suggest that the chronic arthritis symptoms of human Lyme disease patients who have already been treated with antibiotics are due to the "antigenic and inflammatory debris" to which these patients continue to mount an immune response, rather than to true chronically active Lyme infection. "The multiple methods applied in this study," writes Dr. Bockenstedt, "provide a preponderance of evidence that infectious spirochetes are eliminated." Dr. Gary Wormser of New York Medical College, along with several of his colleagues, has expressed a similar viewpoint.
Other researchers disagree. According to a review of the literature conducted by Keith Berndtson of Park Ridge MultiMed in Illinois, "Lyme disease spirochetes are adapted to persist in immune competent hosts" and that these spirochetes can "remain infective despite aggressive antibiotic challenge." Raphael Stricker and Lorraine Johnson of the International Lyme and Associated Diseases Society have published a paper describing the mechanism of action of aggrecanase, an enzyme produced by B. burgdorferi that attacks joint tissue; they assert that evidence of aggrecanase activity is also evidence of the existence of chronically active Lyme infection.
In the April 18, 2014, Morbidity and Mortality Weekly Report, the CDC cautioned the public against the use of a Lyme disease test from Advanced Laboratory Services in Philadelphia, stating that mere receipt by a lab of Clinical Laboratory Improvement Amendments (CLIA) certification does not mean that all tests developed by that lab have received FDA approval. The Advanced Laboratory Services test involves sampling patients' sera, culturing it, and subsequently testing it for spirochetes. In general, the CDC does not recommend culturing or PCR to test for Lyme infection.
In order to gain a better understanding of the issues involved in Lyme infection and testing, the Allentown Family Health Examiner spoke with Dr. Philip M. Tierno, Jr., clinical professor of pathology and microbiology at NYU Langone Medical Center. The conversation is presented here.