What is the cause of my new client’s 20-year struggle isolating him from life, with so little energy and being depressed? Is he a targeted individual? Is there a chronic viral infection?

You were shown intuitively, in looking for possibilities, that a chronic viral infection is the culprit here. This also fits with his very benign story, not having much to report in the way of travails other than a general personal decline of his capabilities and ability to perform and level of energy. Even though this is the case, and would normally indicate to you that the Lightworker Healing Protocol alone will be the answer, that is true up to a point. There are still things in the deep subconscious about his health that can represent roadblocks to divine healing in a quick fashion. So doing some subconscious channeling and trauma resolution for having impaired health and well-being would be productive and highly useful as well.