Humans contract Lyme disease via the bite of an infected tick, according to Mayo Clinic. When an infected tick bites a human, it passes the Borrelia burgdorferi bacterium through the skin and into the person's bloodstream.
The Centers for Disease Control and Prevention reports that most cases of Lyme disease are transmitted by immature ticks. These ticks are called nymphs. Because nymphs are very tiny, it is difficult to spot them and remove them before they can transmit Borrelia burgdorferi. The western blacklegged tick spreads Lyme disease on the Pacific Coast, while the deer tick spreads Lyme disease in the north-central, mid-Atlantic and northeastern United States.
It is possible to prevent Lyme disease by taking several precautions when spending time outdoors. Wearing long pants and long-sleeved shirts prevents infected ticks from coming into contact with the skin. Tucking a shirt into a pair of pants or pant legs into socks also helps prevent contact with infected ticks. For people who cannot avoid tick-infested areas, wearing light-colored clothing makes it easier to identify ticks before they attach to the skin. Outdoor enthusiasts should also use insect repellent before hiking or engaging in other outdoor activities. After spending time outdoors, check every part of the body for ticks, as recommended by LymeDisease.org.