It's absurd to view the Koreas in isolation since they were both extremely obviously the subjects of a proxy war in which one side lost decisively. The two countries' economies were driven by export and the US and USSR were by far their largest partners. That wasn't an accident.
More to the point, I think framing it as "authoritarian governments cause the spread of disease" is misleading. The spread is not caused by accident or economic failure, it's caused by apathy (although obviously a failed state can't fight parasites). The reason hookworm is found in relatively wealthy southeast asian countries is the same as the reason it has been found in rural Alabama; the governments don't care about everyone. It's not accurate to call that authoritarianism and it's misleading to assume it's simply economic failure.