Lyme Disease

How Is Lyme Disease Spread?

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Lyme disease is primarily spread by bites from deer ticks, Western black-legged ticks, and lone star ticks.  Ticks often feed on small rodents, birds, deer, and other non-human animals.  These animals may act as reservoirs for the Lyme disease bacteria (they carry the bacteria, but do not develop symptoms of the disease).  If a tick feeds on an animal that carries the Lyme bacteria, the bacteria will enter the tick’s body, making it able to pass the bacteria on to other animals.  If a tick carrying the bacteria bites a human and remains attached for over 24 hours, the bacteria may enter the human’s blood stream and cause infection.

There are also some reports of pregnant women transmitting the Lyme bacteria to the fetus through the placenta.  This may result in the child being born with Lyme disease, or it may result in birth defects or stillbirth (see Lyme Disease and Pregnancy).