Introduction 

Lyme disease is an infection caused by the spirochete Borrelia burgdorferi, which enters the host after a bite by a tick

-Most cases of Lyme disease occur in the northeast United States between April and November

-It is the most common tick-borne illness and the most common vector-borne zoonotic infection in the United States, 

Symptoms & Signs 

Once a human is infected, disease progression is categorized into three stages: Early localized, Early disseminated, and Late persistent

Stage 1: Early Localized Disease

-Characterized by erythema migrans, which is described as “bull’s-eye” eruption. 

-it is a flat, nonpruritic, erythematous, maculopapular lesion near the site of infection

– Erythema progresses with central clearing 

-it can be accompanied by fever, chills, fatigue, myalgias, arthralgias, and lymphadenopathy

Stage 2: Early Disseminated Disease

-it occurs within a few days to months of the initial infection

-it can involve multiple organs

Fatigue: persistent fatigue is a hallmark of untreated disseminated Lyme disease 

Joints: Asymmetric oligoarticular arthritis of the large joints, particularly the knees; Migratory pains in muscles, joints, and periarticular structures 

Nervous system: it can produce both central and peripheral nervous system disease, acute as well as chronic 

CNS: meningitis or meningoencephalitis, headache, dementia, depression

Cranial nerves:  unilateral or bilateral facial nerve palsy

PNS: painful peripheral radiculopathy 

Heart: Conduction system abnormalities, myocarditis, pericarditis, AV block 

-the most common cardiac manifestation: Atrioventricular blockade

Stage 3: Late Persistent Disease 

-Less than 10% of patients with acute Lyme disease develop chronic manifestations of the disorder

-It can manifest as chronic arthritis, diffuse musculoskeletal pains, myocarditis, subacute encephalopathy, axonal polyneuropathy, chronic insomnia, and leukoencephalopathy

Diagnosis 

Enzyme-linked immunosorbent assay (ELISA), Western blot (immunoglobulin IgM and IgG for B. burgdorferi), CSF analysis (the mononuclear pleocytosis typical of Lyme infection)

Treatment 

Antibiotic treatment is indicated for all stages of Lyme disease

Doxycycline, Amoxicillin, Cefuroxime, Ceftriaxone, Cefotaxime, Penicillin G, erythromycin 

Do not use doxycycline in children under 9 years of age 

Prognosis 

Most manifestations resolve over time even without therapy

Q. What is the most common neurologic manifestation of Lyme disease? Bell palsy (seventh cranial nerve)

Q. What is the hallmark skin lesion of early Lyme disease? Erythema migrans