My son has ehrlichia. He first tested positive almost three years ago. His PANS symptoms(neuropsychiatric) were the only symptoms of it and lyme, outside of the fact that he was fatigued and the bottoms of his feet hurt (bartonella). It has been very difficult to rid him of it. He still has high titers to ehrlichia that stay elevated and go up and down but never back to normal. We are still working to rid him of it. That said, he is doing very well now. We treated him for lyme, although he was CDC/Igenex negative but he had many indeterminate, lyme specific bands and a couple of positive lyme specific bands. He has also been treated for bartonella, though he only had symptoms, no positive tests. Bartonella testing is not very accurate. He has an IgA deficiency that makes it difficult for him to kick infections.
My son has had IVIG twice. I doubt the IVIG was the source. Besides being symptomatic before the IVIG, which is the reason he had IVIG, the filters that remove the Ig would separate out bacteria from the blood as well, since Ig is smaller than bacteria. Ig is made by running blood through filters to sort out the Ig. Viruses are smaller than Ig, so they may ride along with the Ig.