Lyme Disease Propelled by Borrelia burgdorferi-Infected Blacklegged Ticks, Wild Birds and Public Awareness ─ Not Climate Change

The blacklegged tick, Ixodes scapularis, is of major public health importance as a vector of Borrelia burgdorferi, the causal organism of Lyme disease. Migratory songbirds are involved in short- and longdistance transport of bird-feeding ticks, and play a vital role in the wide dispersal of I. scapularis and the epidemiology of Lyme disease. Because northern latitudes generally have a thick blanket of snow each winter, the blacklegged tick withstands phenomenal outdoor temperature fluctuations. However, when the snow cover is lost in the core months of winter, due to subtle periods of warmer temperatures, we discovered that overwinter survival declined significantly. Photoperiod is a limiting factor in the pole-ward expansion and establishment of I. scapularis because immature stages of I. scapularis will not molt in late summer when photoperiod shortens quickly. As more and more people become aware of ticks and their associated pathogens, people submit more ticks for identification and testing. As a result, public awareness becomes a driver in the recognition of Lyme disease, and the number of human cases reported. When it comes to I. scapularis ticks, climate change is a triviality. Health professionals must be aware that Lyme disease and tickassociated diseases are a significant public health burden, and include them in their differential diagnosis.