He will bring upon you and your descendants extraordinary disasters, severe and lasting plagues, and terrible and chronic sicknesses.
KJV
Then the LORD will make thy plagues wonderful, and the plagues of thy seed, [even] great plagues, and of long continuance, and sore sicknesses, and of long continuance.
ASV
then Jehovah will make thy plagues wonderful, and the plagues of thy seed, even great plagues, and of long continuance, and sore sicknesses, and of long continuance.