In Lyme disease – colloquially called tick-borne disease – (synonyms: Borrelia burgdorferi; Borrelia; Borreliosis; Erythema chronicum migrans; Erythema chronicum migrans due to Borrelia burgdorferi after tick bite; Erythema chronicum migrans due to Borrelia; Erythema migrans; Exanthema chronicum migrans; Infection by Borrelia burgdorferi; Lyme borreliosis; Lyme borreliosis; Lyme disease; Lyme disease; relapsing fever; relapsing fever-Borrelia; spirillium fever; ICD-10-GM A68. 1: Tick-borne relapsing fever; ICD-10-GM A68.9: Relapsing fever, unspecified, ICD-10-GM A69.2: Lyme disease/erythema chronicum migrans caused by Borrelia burgdorferi) is an infectious disease caused by the bacterium Borrelia burgdorferi. The disease is caused by bacteria from the Borrelia group (gram-negative), which belong to the spirochete family. A new genetic variant of Borrelia burgdorferi, called Borrelia mayonii, is thought to cause more severe bacteremia (presence of bacteria in the blood) with sometimes atypical symptoms. The new pathogen has so far been found exclusively in samples from the U.S. states of Minnesota, North Dakota, and Wisconsin in the North Central region. Pathogen reservoirs are small rodents and birds. Deer and elk are important hosts for ticks. Lyme disease occurs throughout the Northern Hemisphere, and is also thought to be widespread in Germany. Seasonal accumulation of the disease: Infection can occur from March to October, rarely earlier or later, depending on the weather. Ticks become active when temperatures reach between 8-10 °C permanently. A “hungry” tick is about 3 mm in size, after an extensive blood meal, especially female ticks reach a size of up to 3 cm. Note: Due to climate change, ticks are now active almost all year round in many areas of Germany and Switzerland! In Central Europe, the pathogen is transmitted by the bite of the shield tick Ixodes ricinus (wood tick), which lurks mainly in tall grass. It is assumed that up to 35% of ticks are infected with the pathogen. These ticks are also responsible for the transmission of early summer meningoencephalitis (TBE). Lyme disease occurs in 2-6% of people bitten by a tick. The risk of transmission increases with the duration of the sucking act. The probability of transmission to humans is low within the first 24 hours of adhesion of the ticks – after that it increases significantly. The pathogen enters the body parenterally (pathogen does not penetrate through the intestine, but enters the blood through the skin (percutaneous infection)). The incubation period (time from infection to onset of disease) can last days to months, depending on the stage: days to weeks for stage I, weeks to months for stage II, and months to years for stage III. Peak incidence: Lyme disease is most common in children between the ages of five and nine and in older individuals between the ages of 60 and 69. Children are at higher risk for neuroborreliosis. Neuroborreliosis is a complication of Lyme disease, meaning the bacterium affects the brain and nerve pathways. The Borrelia seroprevalence rate (positive Borrelia serology) is 5-20% of healthy individuals in Germany and Austria. The incidence (frequency of new cases) is about 0.1-0.5 cases per year in Germany. The disease does not lead to immunity. Course and prognosis: The disease is easily treatable if detected in time. If the disease is not detected early, late sequelae such as arthropathy (e.g. oligoarthritis; occurrence of arthritis (joint inflammation) in less than 5 joints; mostly large joints such as the knee joint are affected), myocarditis (heart muscle inflammation) or neuropathy (nerve damage) are possible. Overall, the prognosis is good after adequate antibiotic treatment. In about 95 percent of cases, even neuroborreliosis heals without consequences.After 10 or more years of Lyme disease infection, some patients complain of nonspecific symptoms associated with a “post-Lyme syndrome” (PTLDS, post-treatment Lyme disease symptoms). Its existence is questioned by infectiologists. A population-based cohort study also failed to identify negative effects on social life and occupational success.The current S3 guideline on neuroborreliosis also contradicts the theory of chronic late effects. Vaccination: A vaccination against Lyme disease is not yet available. In Germany, the disease is generally not notifiable according to the Infection Protection Act (IfSG). However, on the basis of state regulations, there is an obligation to report in the following federal states: Bavaria, Berlin, Brandenburg, Mecklenburg-Western Pomerania, Rhineland-Palatinate, Saarland, Saxony-Anhalt, Saxony and Thuringia.
