Black-legged (Deer) Tick -

The bacteria responsible for Lyme disease in the United States, primarily Borrelia burgdorferi and rarely B. mayonii, are transmitted to humans through the bites of infected ticks, notably the black-legged tick (or deer tick). Black-legged ticks undergo a 2-to-3-year life cycle, progressing through four stages: egg, larva, nymph, and adult. Larval and nymphal ticks become infected with Lyme disease bacteria while feeding on infected wildlife hosts, such as rodents, and can then transmit the bacteria during their subsequent blood meals as nymphs or adult females.

Tick attachment for a significant duration, typically 36 to 48 hours or more, is usually required for the transmission of Lyme disease bacteria. Prompt removal of ticks within 24 hours significantly reduces the risk of contracting the disease. In regions where Lyme disease cases are prevalent, people may encounter infected blacklegged ticks from spring through fall, with nymphal ticks posing a higher risk due to their abundance and small size, often making them difficult to detect. Although adult female ticks can also transmit the bacteria, their larger size makes them more noticeable and easier to remove before transmission occurs.

Prevention of Lyme disease primarily involves avoiding tick bites and promptly removing ticks when found attached to the skin. Awareness of the seasonal activity patterns of black-legged ticks, particularly nymphs during spring and summer, is crucial for minimizing the risk of tick-borne infections. Additionally, recognizing the importance of deer as sources of blood for ticks, although not carriers of Lyme disease bacteria themselves, is essential for understanding tick ecology and disease transmission dynamics.