Detection of erythrovirus B19 in thyroidectomy specimens from Graves' disease patients: a case-control study

Environmental factors, such as viruses, are thought to contribute to the development of thyroid autoimmunity. Erythrovirus B19 (EVB19) is suspected to be involved in Hashimoto's thyroiditis, but no direct evidence is available concerning the role of EVB19 infection in Graves' disease. The objective of this study was to investigate whether the presence of EVB19 is more frequent in thyroidectomy specimens of patients undergoing thyroidectomy for Graves' disease (cases) than for multinodular thyroid (controls). Serum and thyroidectomy specimens were prospectively collected from 64 patients referred for total thyroidectomy over a 5-year period (2007-2011) and were investigated retrospectively and blindly for circulating EVB19 DNA by q-PCR (Qiagen), and for EVB19 thyrocyte infection by immunochemistry (VP2-Antibody, Dako). EVB19 serology was also determined. General clinical and laboratory data were collected. Twenty patients were referred for Graves' disease and 44 patients were referred for non-autoimmune multinodular thyroid. Patients with thyroid cancer were excluded. Ten percent of Graves' disease patients and 27.7% of control patients had positive staining of thyrocytes for EVB19 antibodies (ns). EVB19-positive and EVB19-negative cases did not differ. EVB19-positive controls were older than EVB19-negative controls (mean age: 57.5 [35-74] vs. 45 [28-80] years, P=0.03) No case of acute EVB19 infection was identified. EVB19-positive serology was more frequent in controls than in Graves' disease patients (88% vs. 45%, P<0.0001). EVB19 was detected in thyrocytes, but not more frequently in Graves' disease patients than in controls. Further studies are needed to determine the role of EVB19 infection in thyroid diseases.