Bird mites

I’ve had a terrible rat mite problem for 3 years. I’ve lost access to my bedroom and my study room. I’ve had pest control come in to leave rat traps and spray for rat mites. I haven’t seen a rat in over 2 years, but after 3 months of pest control spray, the mites keep returning. What am I doing wrong? Why do the rat mites keep returning? Toronto

If rats have indeed been eliminated from your premises, your problem may not be rat mites, as these cannot complete their life cycle on humans alone. I suggest inspecting the exterior of the home and immediate surroundings for bird nests. Bird mites often are mistaken for rat mites, and like rat mites, these will invade homes and feed on humans in the absence of their usual hosts.