The wonderful world of insects

Toxo is the exception that proves the rule here. Toxo is perhaps the best known example of any parasite having human behavioral effects, yet the causal role of toxo is still not accepted, and what it's postulated to affect is pretty random: schizophrenia, car accidents, that sort of thing. That doesn't look like any kind of planned behavioral control which might affect toxo reproduction. It just looks like a parasite causing some damage post-infection. It's unclear if it even manages to replicate the mouse effect of making humans more attracted to cats (since we contract it mostly from cats, obvious confound). You certainly cannot compare its capabilities, in rodents or primates, to the astonishingly precise and complicated behaviors that insect parasites can orchestrate. And it's not like humans in the wild don't host plenty of parasites!

Unlikely. That would be inconsistent with the heritability, for one thing, for which no genetic correlations with immune-related things have ever been reported that I've seen, and with the best attempts at finding a physical cause landing on things like under-reactive amygdalas and other things one might describe as general brain damage (like toxo) rather than any kind of cunning plan to spread a particular virus/parasite. (How would psychopathy spread a virus? It'd have to be an STD, I guess, except symptoms of psychopathy often show up in childhood and long before individuals have ever had sex, which is also problematic.) Psychopaths do seem fairly fertile, though, which is why theories sometimes invoke an evolutionary life-history explanation: it's a hawk-dove kind of strategy (adaptive if there are enough suckers around, and weak enough social constraints on psychopathic behavior, which would explain why it seems rarer in traditional rural environments and more common in modern urban environments).