Not everything that glitters is Lyme disease

Incidence of Clinician-Diagnosed Lyme Disease, United States, 2005-2010

Extrapolation from a large medical claims database suggests that 329,000 cases occur annually.

National surveillance provides important information about Lyme disease (LD) but is subject to underreporting and variations in practice. Information is limited about the national epidemiology of LD from other sources. Retrospective analysis of a nationwide health insurance claims database identified patients from 2005–2010 with clinician-diagnosed LD using International Classification of Diseases, Ninth Revision, Clinical Modification, codes and antimicrobial drug prescriptions. Of 103,647,966 person-years, 985 inpatient admissions and 44,445 outpatient LD diagnoses were identified. Epidemiologic patterns were similar to US surveillance data overall. Outpatient incidence was highest among boys 5–9 years of age and persons of both sexes 60–64 years of age. On the basis of extrapolation to the US population and application of correction factors for coding, we estimate that annual incidence is 106.6 cases/100,000 persons and that ≈329,000 (95% credible interval 296,000–376,000) LD cases occur annually. LD is a major US public health problem that causes substantial use of health care resources.

Lyme borreliosis

Lyme borreliosis (Lyme disease) is often said to be associated with "protean" manifestations, a reference to the ancient god Proteus, who could assume many forms and thus elude his pursuers. This legendary quality has clouded our understanding of Lyme borreliosis by giving Borrelia burgdorferi infection a mythical aura of its own. This review shows that this illness, while incompletely understood, is far more palpable than Proteus and is (in most cases) much more readily subdued. The clinical presentations of Lyme borreliosis do differ in North America and Eurasia, possibly due to the differing pathogenicity of distinct genospecies of Borrelia burgdorferi. The most common manifestation, however, in both continents is erythema migrans. Diagnosis should rest on a careful history and objective clinical findings, supported by appropriately chosen laboratory tests. Reports of coinfection with other tick-borne diseases should prompt a fresh look at Lyme borreliosis. Assertions about "protean manifestations" of B burgdorferi infection should be reappraised. Advances in laboratory techniques are welcome but culture remains the gold standard for the diagnosis--and no laboratory test result should substitute for careful clinical observation and critical analysis.