Understanding of the aetiological basis of thyroid autoimmunity may be gained by studying the early stages of the disease process. We aimed to (1) investigate the relationship between thyroid antibody status and Yersinia enterocolitica (YE)
infection in euthyroid subjects and (2) explore the relative importance of genetic and environmental risk factors in the acquisition of YE
infection. The association between thyroid antibody status and YE
infection was explored using a case-control design. Furthermore, thyroid antibody-positive twins were compared with their thyroid antibody-negative co-twin. In 468 twins,
IgA and
IgG antibodies to virulence-associated outer-
membrane proteins (YOPs) of YE were measured. Of these, 147 were thyroid antibody-positive (cases). A total of 147 age- and gender-matched twins were chosen as controls. The prevalence of YOP
antibodies was lower among thyroid antibody-positive individuals than among controls.
Yersinia infection was not associated with a positive thyroid antibody status: the odds ratio (with 95% CI) for YOP
IgA-ab was 0.66 (0.42-1.05), P = 0.078 and for YOP
IgG-ab it was 0.95 (0.60-1.50), P = 0.816. Within discordant twin pairs, the thyroid antibody-positive twin did not have an increased risk of
Yersinia infection compared to the thyroid antibody-negative co-twin [odds ratio: YOP
IgA-Ab: 0.94 (0.49-1.83), P = 0.866, and YOP
IgG-Ab: 1.35 (0.72-2.53), P = 0.345]; 41% (95% CI 10-67% of the liability of being YOP antibody-positive was due to genetic effects. In conclusion,
Yersinia infection does not confer an increased risk of thyroid
antibodies. The genetic contribution in the acquisition of
Yersinia infection is modest.