I know Prof. Edwards is an immunologist, but I know of a researcher in the UK who is working of the role of Yersinia Enterocolitica in Graves´s Disease. There is a lot of debate about this it seems, but I don´t think the issue has been settled yet (although I´m sure Prof. Edwards will say it has been). This is a interesting recent study: http://www.ncbi.nlm.nih.gov/pubmed/21488870 It looks like reasonably good evidence against a causal role, but the other interesting thing about it when you actually study it in detail is the prevalence of Yersinia antibodies in the study population (both cases and controls were related to people with autoimmune disease). They found around 30% were positive for IgA! This significantly higher than in any of the seroprevalence studies of the general population. The authors go on to suggest an explanation for this fact: A higher prevalence of YOP IgG and IgA in female relatives of patients with AITD than in controls derived from the general population has been reported previously . The higher rate of persistent YE infection in AITD relatives might be due to susceptibility genes for AITD contributing to the risk for YE infection. The Danish twin study indicated that the genetic contribution in the association with YE is modest, and that it is more likely that environmental exposures to confer to the reported association between and YE and AITD . So, even if Yersinia doesn´t cause thyroid disease, the fact that a person has thyroid disease may mean that they might also have Yersinia infection!