We enrolled adult patients with Lyme disease in a prospective study at the Lyme Disease Diagnostic Center, in Westchester County in the Lower Hudson Valley region of New York, to assess the outcome of this infection over 1 year, as described elsewhere. The Lower Hudson Valley region of New York is defined as Westchester, Putnam, Dutchess, Rockland, Orange, Ulster, and Sullivan Counties. This report focuses on 52 persons who at the time of study entry had erythema migrans but no treatment for Lyme disease and no clinical evidence of a concomitant extracutaneous manifestation of Lyme disease. Each patient had ≥1 expanding erythematous skin lesion that was ≥5 cm in diameter.[11,12]
For each of the 52 persons with erythema migrans, baseline visits occurred from June 2, 2011, through July 30, 2015; blood was collected before antimicrobial drug treatment began (baseline) and at the next follow-up visit. The study was approved by the institutional review board at New York Medical College.
Testing and Confirmation of Infection
Serologic testing to document co-infection was performed retrospectively. Testing for antibodies to A. phagocytophilum was conducted by immunofluorescent assay at Focus Diagnostics, Inc. (Cypress, CA, USA). Testing for antibodies to B. microti was done by immunofluorescent assay at either Focus Diagnostics, Inc., or at the New York State Department of Health Wadsworth Center (Albany, NY, USA).
Testing for antibodies to the glycerophosphodiester phosphodiesterase (GlpQ) protein of B. miyamotoi was performed at the Wadsworth Center by using a microsphere immunoassay that detects total antibodies (IgG + IgA + IgM) to recombinant GlpQ of B. miyamotoi. The recombinant GlpQ was kindly provided by Sukanya Narasimhan and Erol Fikrig of Yale University (New Haven, CT, USA).
Testing for antibodies to POWV was also performed at the Wadsworth Center. Serologic testing for POWV infection included a microsphere immunoassay to detect total antibodies (IgG + IgA + IgM) to recombinant deer tick virus envelope protein and an IgM capture enzyme immunoassay to the LB strain of POWV. When the microsphere immunoassay and the IgM capture enzyme immunoassay were both reactive on acute- or convalescent-phase serum specimens, plaque reduction testing for neutralization antibodies against the LB strain of POWV was also performed.
Serologic evidence of A. phagocytophilum co-infection required a 4-fold rise in IgG titer between the acute- and convalescent-phase samples to ≥1:512. Serologic evidence of B. microtiinfection required a 4-fold rise in IgG titers between the acute- and convalescent-phase serum samples. Patients who had clinical evidence of A. phagocytophilum or B. microti infections (e.g., new onset of fever, characteristic hematologic abnormalities, or both), or in whom such clinical evidence developed, were also tested when these findings were observed, by blood smear, PCR, or both, to detect these microorganisms, as described elsewhere.[13,14] Because a positive result on the acute-phase sample is atypical for acute B. miyamotoi infection, serologic evidence of B. miyamotoi infection required seroconversion in the convalescent-phase sample for antibody to GlpQ. A diagnosis of possible POWV co-infection required a finding of positive IgM and neutralizing antibodies to POWV for the same serum sample. A confirmed diagnosis of POWV co-infection, however, required a 4-fold rise in neutralizing antibodies between the acute- and convalescent-phase serum samples; in addition, the neutralizing titer value had to exceed by >4-fold the neutralizing antibody titers found by using the patient's serum under the same test conditions but using other flaviviruses, such as West Nile virus.
At each patient's baseline visit, we collected demographic and clinical data, including data on 12 somatic symptoms (e.g., fatigue, headache, joint pain, muscle pain, and cognitive complaints), as described elsewhere.[10,16] We performed serologic testing for Lyme disease at both the baseline and convalescent visits by using the C6 Lyme ELISA kit (Immunetics, Inc., https://www.oxfordimmunotec.com) according to the manufacturer's recommendations.
For comparison of categorical variables, we used the Fisher exact test or the exact McNemar test; for continuous variables, we used the Student t-test. All testing was 2-tailed. We considered p<0.05 to be significant.
Emerging Infectious Diseases. 2019;25(4):748-752. © 2019 Centers for Disease Control and Prevention (CDC)