What is Lyme Disease (Lime Disease)?
Lyme disease is a tick-borne multisystem infectious syndrome of substantial medical importance and public concern. It is the most frequently reported vector-borne illness in the United States, occurring in 48 of the 50 states at rates of up to 12,000 cases annually. Lime disease also has been seen on four other continents.
The causative organism, Borrelia burgdorferi, is a flagellated spirochete transmitted from small-mammal reservoirs to humans through bites from infected ticks of Ixodes species (I scapularis in the eastern and upper midwestern United States, I pacificus in California, I ricinus in Europe, and I persulcatus in Asia). Commonly known as deer ticks in the United States and sheep ticks in Europe, these Lime disease vectors are, limes disease.
Ticks must obtain a blood meal in order to molt and lay eggs, leading to obligatory parasitism of suitable hosts: mammals, reptiles, amphibians, and birds in various locales. Humans become suitable alternative hosts when participating in activities in wooded habitats in areas where ixodid ticks are prevalent. In endemic regions, B burgdorferi moves through enzootic cycles between ticks and reservoir hosts capable of sustaining B burgdorferi infection. Humans are at risk for Lime disease when exposed to infected ticks questing for a blood meal.
In nonendemic regions, immature ticks preferentially parasitize hosts that are genetic variation in B burgdorferi isolates from different geographic regions may explain observed differences in the clinical manifestations of lime disease in Europe and North America.
Arthritis is more common in the United States, where all human isolates have belonged to the species B burgdorferi sensu stricto.
In parts of Europe, chronic dermatological manifestations (eg, acrodermatitis chronica atrophicans) are often associated with Borrelia afzelii and some neurological manifestations (notably meningopolyneuritis, or Bannwarth’s syndrome).