I think you could argue that humans certainly are parasitic!
Yesterday I read about ‘the microbe’s dilemma’: ‘in the church, he drew away from me again… I traced a streak of blue on the white marble floor, meandering like one the of the veins on the inside of his arm. We’re like microbes, I said, we’re in the same dilemma as microbes might be, trying to wave to the person looking down the microscope.’ Sue Wolfe, ‘Leaning Towards Infinity’