Which bacterium is primarily responsible for causing Lyme disease?

Borrelia burgdorferi is the bacterium primarily responsible for causing Lyme disease. This spirochete bacterium is transmitted to humans through the bite of infected black-legged ticks, commonly known as deer ticks. Lyme disease is characterized by a range of symptoms, including erythema migrans (a distinctive rash often described as a "bull's-eye"), fever, fatigue, and in more severe cases, joint pain and neurological issues.

Understanding the biology and transmission of Borrelia burgdorferi is critical for prevention and treatment strategies. Recognizing the vector (the tick) and the appropriate settings for exposure can aid in reducing the incidence of the disease. The other bacteria listed are associated with different diseases: Streptococcus pneumoniae is known for causing pneumonia and meningitis, Escherichia coli is commonly linked to gastrointestinal infections, and Neisseria meningitidis causes meningococcal disease. None of these are related to Lyme disease, which underscores the specific pathogenic role of Borrelia burgdorferi in this context.