Let's look at what is being said. What is the lesson we are to learn from this chapter?
15:3 The LORD [is] a man of war: the LORD [is] his name.
15:4 Pharaoh's chariots and his host hath he cast into the sea: his chosen captains also are drowned in the Red sea.
15:5 The depths have covered them: they sank into the bottom as a stone.
15:6 Thy right hand, O LORD, is become glorious in power: thy right hand, O LORD, hath dashed in pieces the enemy.
15:7 And in the greatness of thine excellency thou hast overthrown them that rose up against thee: thou sentest forth thy wrath, [which] consumed them as stubble.
15:8 And with the blast of thy nostrils the waters were gathered together, the floods stood upright as an heap, [and] the depths were congealed in the heart of the sea.
15:9 The enemy said, I will pursue, I will overtake, I will divide the spoil; my lust shall be satisfied upon them; I will draw my sword, my hand shall destroy them.
15:10 Thou didst blow with thy wind, the sea covered them: they sank as lead in the mighty waters.
15:11 Who [is] like unto thee, O LORD, among the gods? who [is] like thee, glorious in holiness, fearful [in] praises, doing wonders?
God is omnipotent. He will literally destroy the enemy. What does that have to do with the verse we are seeking light on?
Maybe we need to look a little further back, to see if God in fact ever used disease as punishment to the Egyptians? Would God do that? Most don't think so. God is too loving, even if He did drown the Egyptians.......and every living person on the Earth except for those in the ark.
So, in context, if we go back a little further to see if God would bring any disease upon Israel, did He?
There is a lesson in the verse. "If thou wilt diligently hearken to the voice of the LORD thy God, and wilt do that which is right in his sight, and wilt give ear to his commandments, and keep all his statutes, I will put none of these diseases upon thee, which I have brought upon the Egyptians." Many don't want to hear the lesson. Why not?