Lyme is a funny bacterium, it is a cousin to Syphilis (both are spirochetes). It doesnt live in the blood , so testing can be iffy. If the bite is recent enough, finding antibodies can be iffy. People can get bitten, have the immune system high enough so the bug will literally shed DNA and go into cyst form, still there, but untestable and no symptoms. Then later on, the person gets sick, or has a big stress, the cyst will reform and the Lyme infection begins. My Dr explained this as an underwater volcano, its there, building and growing mass but you dont know it untill it breaks surface. By the time it causes symptoms and you actually get a diagnosis, it can be a mile high.