The unchanging fact is that Borrelia burgdorferi infection doesn’t pass vertically between blacklegged ticks. In plainer language: It is not inherited. Of those million baby ticks, all derived from the female ticks that fed on a single deer, none will be carrying B. burgdorferi when they hatch—not even if every mother tick was infected and the deer was too. The youngsters will come into the world clean and healthy. Each generation of ticks must be infected anew.