Shingles is very commonly brought on by stress. It's latent chickenpox virus, which is usually kept in check by the immune system, but stress depresses immune response.

I had a coworker who developed shingles as we were nearing the deadline on a project that had all sorts of problems in layers of the stack we didn't control, and my sister developed shingles after being laid off. The first thing I associate with that disease is stress.