When someone has an ongoing, active infection with Lyme your IgM antibodies should be positive which indicates acute or ongoing infection. After you've been tre

When someone has an ongoing, active infection with Lyme your IgM antibodies should be positive which indicates acute or ongoing infection. After you've been treated for Lyme disease your IgG levels will remain positive, but your IgM should disappear. So no, it's not impossible to tell if they have an active infection and my point still stands. There's a whole community of people who may (or may not) have had Lyme disease in the past and blame anything and everything on it. Lyme disease can cause permanent conditions neurological degradation that won't go away once the infection has been treated, or it may be something completely different. However, "chronic Lyme disease" is not a thing.