I understood the Hygeine Hypoth: is concerned with external hygiene rather than internal. That is our modern lifestyle of over washing and cleaning with chemicals etc. This is what I read and listened to on video by a proponent of HH. there was no mention of internal uncleanlines thru use of antibiotics. Some of the poorest people in the world e.g Afrika living in squalid conditions are the ones who get severe parasite infections. So I'm in the dark about this one. I shall see if I can find that video.