In those with ADHD due to other causes, in what percent of cases might presence of a chronic virus in the brain be an aggravating factor that worsens symptoms?

Given that those with ADHD are a subset of the population, and so are those harboring a chronic viral infection within the brain, we would say that those with ADHD at a level warranting diagnosis not caused by a chronic virus, will have such a chronic infection about 5% of the time. So it is only a 5% figure for those with a non-viral cause for their symptoms, but having acquired an aggravating viral presence to worsen things.