Prognosis

If patients are diagnosed and treated properly with recommended antibiotic therapy, Lyme disease is usually curable. Prognosis of patients with erythema migrans post-treatment is excellent, with more than 90% making a complete recovery.[62]​ After treatment, 75% to 80% of patients with neuroborreliosis recover completely within one year. Sequelae like paresis or neuropathic pain may persist in 5% to 28% of patients.[63]​ It is estimated that around 90% of patients with Lyme-related arthritis recover completely.[1][63]​ Lyme carditis complications tend to be acute in nature and chronic complications are rare.[63]​

A small proportion of patients may report subjective symptoms, including fatigue, musculoskeletal pain, and neurocognitive disturbances, for several months after appropriate antibiotic therapy, without any evidence of ongoing infection.[1][25]​​​ When symptoms last for 6 months or longer this is sometimes referred to as "chronic Lyme disease" or "post-treatment Lyme disease syndrome.” However, studies have failed to show that these symptoms are in excess of what is expected in noninfected patients.[64][65]​​ In one randomized, double-blinded, placebo-controlled clinical trial, conducted in Europe, longer-term antibiotic treatment did not provide any additional benefit to patients with persistent symptoms attributed to Lyme disease.[66] The prevalence of post-treatment Lyme disease has been estimated to be 10% to 20% in North America.[67]​​

Reinfection can occur in patients who have a repeat tick bite. Relapse has not been reported in patients who received appropriate antibiotic treatment.

Individuals who go untreated, or receive delayed treatment, may present with features of late stage Lyme disease, including arthritis, neurological symptoms, cutaneous symptoms, and carditis. One prospective cohort study in the 1970s followed 55 patients with untreated erythema migrans for a mean duration of 6 years and found that about 60% had one episode, or began to have intermittent attacks, of frank arthritis, primarily in large joints. The total number who continued to have recurrences decreased by 10% to 20% each year. A minority of patients (11%) developed chronic synovitis later in the illness; of these, 4% had erosions, and 2% permanent joint disability.[68] Most patients with late-stage arthritis can be successfully treated with antibiotics, but 10% to 17% have antibiotic-refractory Lyme arthritis; this is thought to be driven by immunopathogenic mechanisms and thus requires different management strategies.[1]​ The nature of the stimulus that perpetuates synovial inflammation after the apparent eradication of live spirochetes from joints with antibiotic therapy is unknown.[69]

The neurologic manifestations of late Lyme disease include chronic meningitis, progressive encephalitis, myelitis or encephalomyelitis, and cerebral vasculitis. With appropriate antibiotic therapy for early Lyme disease, late neurologic findings have almost disappeared; however, these manifestations of late Lyme disease are rare, even in untreated patients.[70]

In Europe, acrodermatitis chronica atrophicans (ACA) is a cutaneous manifestation of late Lyme disease that may appear years following primary infection (range 0.5 to 8 years).[71] It is primarily due to B afzelii and is the only manifestation of Lyme disease in humans where chronic infection has been unequivocally demonstrated; skin biopsy samples from untreated lesions present for ≥10 years have yielded positive PCR and culture results.​​​[1]​ After antibiotic treatment, culture results become negative, and skin lesions and accompanying signs may resolve completely. Local atrophy may persist in others.[1]​ In Europe, clinical studies have reported signs of polyneuropathy in 40% to 60% of patients who present with ACA; the ACA-associated polyneuropathy is asymmetric and predominantly sensory, and usually follows the skin lesion.[70]

[Figure caption and citation for the preceding image starts]: Acrodermatitis chronica atrophicans​Nguyen AL et al. Case Reports 2016; 2016: bcr2016216033; used with permission [Citation ends].com.bmj.content.model.Caption@d6ff64

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