4 months?  Sounds more like walking pneumonia.  I had that a about six years ago and it was miserable, but I toughed it out and didn't miss work either.  I sterilized everything around me like a crazy person and managed not to spread it to anyone else, unlike the asshat coworker that gave it to me. Edit:  They just did a PCR.  The problem with accuracy is an occasional false negative, not false positives.  That means that if you test positive, it's pretty damn certain you're positive, but if you test negative, then you may be testing too early/late for it to detect the disease.  PCR can only detect an active infection.