Could have been because of the prevalence of trichinosis in pork until relatively recently (i.e. in your grandmother’s lifetime). If your immune system is in good shape, it’s not terribly risky, but if you just came out of the hospital you probably aren’t in peak form. So avoid pork for a while until your body can properly fight off parasites again.

Proper food safety and livestock handling has dramatically reduced the risk of parasite infections from pork in most of the developed world.