Question:

I have two friends that have recently been diagnosed with autoimmune diseases; one has been diagnosed with myasthenia gravis, and the other has not had a name put to her diagnosis as yet. Both friends, not in physical contact with each other at that period, had flu symptoms just before they contracted the disease(s). Are flu symptoms a precursor to autoimmune diseases and/or can the flu lead to such a disease?

Answer:

We do not believe that viral infections or vaccinations cause myasthenia gravis by triggering the immune response. (This is of course different in diseases such as Guillain-Barré syndrome, within which there is a clear relationship between viral infections &vaccinations causing many, but not all cases of the syndrome.) 

With Myasthenia Gravis, there is an autoimmune trigger within the body (thymus pathology) that is often the driving factor in the autoimmune attack of myasthenia gravis.

I say this because in the large majority of cases of Myasthenia Gravis, thymus hyperplasia or a thymoma is found. This is not to say that it is impossible for a viral infection in rare circumstances to trigger the disease. It has not been identified as a strong factor.

As mentioned, viral infections can often worsen myasthenia gravis in patients who already have the disease. Hope this information helps.

For more information:

Go to the Myasthenia Gravis health topic.