> [...] is a viral reservoir, possibly in the gut

In that case, a gastrointestinal lavage (as applied before a colonoscopy) could be a potential remedy. It's a long shot, but since the process doesn't have any side effects (other than the inconvenience of having to change your diet for a few days), it'd be worth a try.

> So people and doctors will throw SSRIs at the problem, and maybe that will relieve some symptoms, but will not address the fundamental cause.

Additionally, SSRIs cause severe - and in many cases permanent - side effects. What's worse, we don't even really know how SSRIs work - or if at all (at least, as intended). Nevertheless, they're handed out like sweets.