Lyme disease is a bacterial infection that people can acquire from the bite of an infected tick. This condition can initially cause symptoms such as a rash, fever, headache, and fatigue. If left untreated, the infection has the potential to spread to various parts of the body, including joints, the heart, and the nervous system. This article clarifies how Lyme disease is transmitted and how to reduce your risk of infection.
Primary Mode of Transmission
Lyme disease is primarily transmitted through the bite of infected blacklegged ticks, also known as deer ticks. In the eastern and central United States, the specific tick species responsible is Ixodes scapularis, while Ixodes pacificus transmits the disease along the Pacific Coast. These ticks have a two-to-three-year life cycle, progressing through four distinct stages: egg, larva, nymph, and adult, each requiring a blood meal to develop.
Ticks become infected with Borrelia burgdorferi bacteria, the cause of Lyme disease in the United States, when they feed on infected wildlife hosts, particularly small mammals like white-footed mice and chipmunks. While larvae, nymphs, and adult ticks can transmit the bacteria, nymphal ticks are responsible for most human infections. Nymphs are quite small, roughly the size of a poppy seed, making them difficult to spot.
For transmission, an infected tick must be attached for a certain duration. The bacterium usually transfers after the tick has been attached for at least 24 hours, with risk increasing if attachment lasts 36 to 48 hours or more. Prompt removal of ticks can substantially reduce the likelihood of contracting Lyme disease.
Dispelling Misconceptions About Transmission
Lyme disease cannot be transmitted directly from person to person. This means the infection does not spread through casual contact, such as touching, kissing, or sexual intercourse. While bacteria have been detected in bodily fluids like breast milk and semen, no conclusive scientific evidence supports human-to-human transmission through these routes.
Pets, particularly dogs, can contract Lyme disease, but they do not directly spread the infection to humans. However, pets can inadvertently carry infected ticks into homes or yards, increasing the potential for human exposure. Therefore, checking pets for ticks after outdoor activities is important.
Lyme disease is also not spread through the air, contaminated food, or water. Other common insects, such as mosquitoes, flies, fleas, or lice, do not transmit the Lyme disease bacteria. Only specific species of infected blacklegged ticks transmit the bacteria that cause Lyme disease to humans in the United States.
Preventing Transmission
Reducing exposure to ticks is the most effective way to prevent Lyme disease. When spending time outdoors, especially in wooded, brushy, or grassy areas where ticks reside, wear long pants and long-sleeved shirts. Tucking your pants into your socks and your shirt into your pants can create a barrier, preventing ticks from crawling onto your skin. Light-colored clothing can also help make ticks more visible, allowing for easier detection.
Using EPA-registered insect repellents is another protective measure. Products containing DEET (20-30%) or picaridin can be applied to exposed skin and clothing to repel ticks. Permethrin, an insecticide that kills ticks on contact, treats clothing and gear but should not be applied directly to skin. Permethrin-treated clothing offers protection through multiple washes.
After returning indoors, perform thorough tick checks on your body, clothing, and gear. Pay close attention to areas like armpits, the scalp, and the groin. Showering within two hours of coming indoors may also help reduce the risk of infection. If a tick is found, remove it promptly using fine-tipped tweezers, grasping it as close to the skin’s surface as possible and pulling upward with steady, even pressure.