Newly hatched ticks do not harbor B. burgdorferi. Rather, they pick it up from certain hosts that are reservoirs of the bacterium. When a larval tick crawls onto a host, it may get groomed off and killed by the host, or it may feed successfully, in which case it may or may not then become infected with B. burgdorferi. Felicia Keesing and others measured the rate of tick feeding and infection on different hosts. What percentage of ticks on mice were infected with B. burgdorferi?

100 percent of ticks on mice were infected with B. burgdorferi.

Explanation:

Ticks become infected with B. burgdorferi if they feed on mice or other host infected with B. burgdorferi. B. burgdorferi is a type of harmful bacteria which is responsible for a disease called Borreliosis. It is also known as Lyme disease. It is mostly occurs from the biting of ticks infected by B. burgdorferiy. All the mice contains B. burgdorferi so 100 percent of ticks were infected by B. burgdorferi.