Sforno on Deuteronomy 7:15/ספורנו על דברים ז׳:ט״ו

1כל חולי, any manner of illness including those that are the result of climactic conditions.

2הרעים, the ones which are contagious.

3אשר ידעת, that the Egyptians were smitten with at the Sea of Reeds.

4לא ישימם בך ונתנם בכל שונאך, even though these diseases will strike your enemies they will not infect you, as described in Psalms 91,7 “thousands may fall by your side….but the source of the death will not reach you.”