Sorry, I don't see any mention of viruses. If you want to take the literalist view, you will have to show me where the Bible mentions viruses.
It doesn't, but it does mention sickness and plagues. And the obvious point is that God retains a certain amount of control of them. Thus He can send them and take them away as He pleases.
And sometimes maybe He just lets them hang out in monkeys and sheep as a judgement on anyone who ignores His dictates.