Ok, but how? Taking medicine doesn't require intelligence so the only deciding factor is whether you get treatment or not.
Does your doctor give you an IQ test and deny treatment if your score is too low?
With those come good health insurance, being able to afford co-pays, being able to take time off work to go to the doctor, being able to comply with complex instructions like changing your diet, being able to research your diagnosis even if it's in lots of long latin words, being able to tell good advice from bad when researching online, being able to take time off for treatment or recovery, knowing the magic incantations to get yourself taken seriously, knowing when it's a good idea to get a second opinion and how to go about that, less stress caused by financial worries or job insecurity, etc etc
Two hypothesis: higher IQ people learn hygiene sooner and manage to avoid getting infected. Higher IQ parents provide both better hygiene and high IQ genes and nurture.
"More intelligent environment" may prevent one from even contacting anything that can get one worms.
For example, most first world urban kids do not eat berries directly from the bushes. These berries they eat are controlled for worms among other things.
