Earlier quoted context omitted.
It gets less interesting when one notices that social animals are much more prone to depression. Inflammation and depression are linked. Infection causes inflammation. It doesn’t follow that depression is caused by infection.
I’m not quite following the previous conversation here, but your comment brings to mind that one theory of a possible “function” of depression, is as a “sickness behavior” to help isolate a sick animal from others to protect the group. A sheep or cow getting sick and going off on its own is a common thing. I’m not sure if it has a technical name or if it’s been rigorously studied, but it’s a common observation which…
It's one explanation of the phenomenon. I'm not remotely convinced by it, but that doesn't mean I think it's untrue.
What I do think we can conclude is that we have no evidence depression is caused by infection. (Singularly and universally, as OP implies.) With higher confidence I believe I can conclude that interrogating chatbots designed to keep your attention is a poor way to resolve this.