To an American audience, yeah, it's definitely better in all caps.

However, The Economist is British, and sometimes in British English they capitalize acronyms that way. Only "true" (pronounceable) acronyms, though, so they'll write Nato ("nay toh") and BBC ("bee bee see").

Clarifying what you mean, all acronyms are pronounceable, otherwise they're just a sparkling initialism.

The article uses "AIDS". It's just the HN title mangler at work.

Hah, my explanation fits the facts perfectly... except for one tiny little detail. I often forget that the title mangler exists.

This was likely the HN title autoformatter at work. I knew what the title was trying to say, but I couldn't help but think of that South Park episode :)

It also might be more accurate to not refer to AIDS as a virus. It is a syndrome caused by HIV. HIV is the virus.

Fixed now.