Verses with the word sicknesses in the Old Testament (2 verses):

Deuteronomy 28:59
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.

Deuteronomy 29:22
So that the generation to come of your children that shall rise up after you, and the stranger that shall come from a far land, shall say, when they see the plagues of that land, and the sicknesses which the LORD hath laid upon it;