If the cause it too many rats in the area, that doesn't explain why your neighbor doesn't have the same health issues as you implied...
he lives near the main road, more kind of urban area, about 1 km from me. I am surrounded by abandoned fields with olive/almond trees and old houses, a perfect place for rats - free food and housing, they just need water and that is why they come (they drink dog's and cat's water in the area as well). I live on the island.