Lyme Disease (Borreliosis): Symptoms, Stages, and Treatment

Lyme disease is caused by bacteria of the genus Borrelia (in Europe most often Borrelia afzelii and Borrelia garinii; in North America mainly Borrelia burgdorferi sensu stricto), transmitted through the bite of an infected tick of the genus Ixodes. A tick bite itself doesn't automatically mean infection — what matters most is how long the tick stays attached to the skin. In most cases, transmission of the bacteria requires at least 36-48 hours of continuous feeding, which makes prompt tick removal one of the most effective, fully accessible prevention methods available.

The most characteristic, though not the only, symptom of early Lyme disease is erythema migrans — an expanding, red or reddish-brown area of skin around the bite site, usually appearing 7-14 days (ranging from 3 to 30 days) after the bite. The rash typically grows gradually, sometimes taking on the characteristic "bull's-eye" appearance with a lighter center, though not always — in some patients the lesion has a uniform color across its whole surface, which can be diagnostically misleading.

Erythema migrans occurs in most, but not all, infected people — some patients never notice the characteristic skin change, especially when it appears in a hard-to-see spot (the scalp, the back) or has an atypical, faint appearance. That's one of the reasons Lyme disease sometimes isn't recognized until a later stage.

If the infection isn't recognized and treated at the rash stage, the bacteria can spread through the bloodstream, leading to the early disseminated stage, usually within weeks to months of the bite. At this point multiple secondary rashes can appear elsewhere on the body, along with flu-like symptoms, and in some patients involvement of the nervous system (neuroborreliosis — facial nerve palsy, meningitis, painful radiculitis) or the heart (conduction disturbances, including atrioventricular block).

It's worth stressing that progression to the disseminated or late stage isn't inevitable — in the large majority of patients treated with antibiotics at the erythema migrans stage, the disease resolves completely, without further progression.

The large majority of patients treated according to these guidelines at an early stage of the disease achieve a full cure. Some patients, however, experience prolonged symptoms — fatigue, musculoskeletal pain, difficulty concentrating — persisting for weeks or months after completing standard treatment, despite microbiological cure of the infection. This phenomenon is sometimes called post-treatment Lyme disease syndrome, and it's exactly the starting point of the controversy described in the next section.

The term "chronic Lyme disease" is sometimes used outside academic medicine to describe long-lasting, nonspecific symptoms (fatigue, musculoskeletal pain, cognitive difficulties) supposedly attributed to a persistent, active Borrelia infection — sometimes in people with no previously documented Lyme diagnosis at all. This is a distinct concept from the clinically recognized post-treatment Lyme disease syndrome (PTLDS), which concerns documented cases of previously correctly diagnosed and treated Lyme disease with persisting symptoms — and this distinction matters a great deal in evaluating the evidence.

Early-stage Lyme disease is one of those infectious diseases where prompt recognition and standard treatment give a very good prognosis — that's good news worth emphasizing instead of only using ticks to scare people. The harder part of the topic, one that requires more skepticism, concerns persistent symptoms and the marketing around "chronic Lyme disease" — here the best available evidence doesn't support the effectiveness of prolonged antibiotic therapy, even though patients' symptoms are real and deserve to be taken seriously along with proper, evidence-based care.

If you suspect you have Lyme disease, the most important first step is seeing a doctor as early as possible, ideally at the first skin symptoms. If you're struggling with persistent symptoms after correctly completed treatment, it's worth seeking care grounded in current guidelines, and approaching offers of many months of costly antibiotic therapy without clear clinical justification with real caution.