This condition is described as rare but hereditary.
Eosinophils which are immune cells invade the esophagus where they cause inflamation, narrowing and difficulty swallowing. These immune cells can also get into the lungs where they can cause asthma. This is a hereditary condition.
They really don't have a cure for this. Some theorize that it's an allergic condition but others do not.
I was born with this and have had difficulty swallowing all my life. As I am 78, best thing for me is babyfood which goes down fine.
They tried to stretch my esophagus with an esophagoplasty (they blow up a balloon in the esophagus). This made the condition worse and they said I would need several esophagoplasties. I was ready to go for my second one when I met an individual who had had several esophagoplasties. He was having a difficult time swallowing water. Needless to say, I decided against another esophagoplasty.