B burgdorferi sl spirochetes are transmitted through the bite of tick species belonging to the genus Ixodes, which are largely confined to temperate climate zones of the northern hemisphere. In North America, the Ixodes species that transmits the causative agent of Lyme borreliosis is primarily Ixodes scapularis; however, Ixodes pacificus also acts as a vector in the western coastal regions.In Europe, Ixodes ricinus is the tick species primarily responsible for transmitting B burgdorferi sl, whereas Ixodes persulcatus is predominant in large parts of Russia and Asia.
Infective stage: Nymph/adult phase
Natural reservoir: Mouse, lizards, birds, etc
Lyme borreliosis is caused by spirochetes belonging to the Borrelia burgdorferi sensu lato (sl) complex, which consists of ~20 genospecies with a complex genomic structure.1 Not all B burgdorferi sl species are pathogenic, and in North America, Borrelia burgdorferi ss is the dominant genospecies associated with Lyme borreliosis, although a novel genospecies, Borrelia mayonii, was recently identified.In Eurasia, B afzelii and B garinii are the most common B burgdorferi sl genospecies in ticks and humans.
USA: Borrelia burgdorferi
Asia, Europe: Borrelia garinii, Borrelia afzeilii
During infection, the bacteria migrate through the host tissues, adhere to certain cells and can evade immune clearance. Yet, these organisms are eventually killed by both innate and adaptive immune responses and most inflammatory manifestations of the infection resolve.
Without antibiotic therapy, the clinical manifestations of the disease typically occur in three stages, beginning with early localized infection of the skin and ending with late infection, most commonly Lyme arthritis in the United States or acrodermatitis chronica atrophicans in Europe.
Stage 1 | Early localized stage:
Infection typically begins during summer with erythema migrans, which occurs at the site of the tick bite. Even without antibiotic therapy, erythema migrans typically improves or resolves within weeks.
Erythema migrans (typical “bulls-eye” configuration): Presenting manifestation in ∼80% cases
Nonspecific symptoms (∼18%)
Borrelial lymphocytoma (rare): Typically located on the earlobe in children or on the nipple in adults
2–3% present with a manifestation of early/late disseminated infection: Facial palsy, trigeminal neuropathy or Lyme arthritis
Stage 2 | Early disseminated stage:
Within days to weeks, B. burgdorferi disseminate from the site of the tick bite to other regions of the body
Peripheral nervous system: Radiculoneuritis (inflammation of the spinal nerve root)
CNS (meningitis) abnormalities
Lyme neuroborreliosis (B. burgdorferi in US): Lymphocytic meningitis with episodic headaches and mild neck stiffness, cranial neuropathy (particularly facial palsy), or motor or sensory radiculoneuritis
Bannwarth syndrome or tick-borne meningopolyneuritis (B. garinii in Europe): Begins with painful radiculoneuritis that is associated with lymphocytic meningitis, often without headache, and can be followed by cranial neuropathy or pareses of the extremities
Other CNS features: Headache, dizziness, concentration and memory disturbances and paresthesia
Cardiac involvement: AV block > Myopericarditis/mild LV dysfunction/cardiomegaly/pancarditis
Stage 3 | Late disseminated stage:
Lyme arthritis: Joint swelling and pain typically occurred in intermittent attacks primarily in large joints, especially the knee, over a period of several years
Acrodermatitis chronica atrophicans/acrodermatitis (ACA) (M/C late manifestation of Lyme borreliosis): Slowly progressive lesion located primarily on the extensor (acral) surfaces of the extremities
Chronic encephalomyelitis: Characterized by spastic paraparesis, cranial neuropathy or cognitive impairment
Lyme borreliosis is diagnosed in a patient who has been previously exposed to ticks and who subsequently developed the typical signs and symptoms associated with Lyme borreliosis, affecting the skin, nervous system, musculoskeletal system and heart
Positive antibody response against Borrelia burgdorferi determined by a two-tiered approach of ELISA & western blooting
All manifestations of the infection can usually be treated with appropriate antibiotic regimens, but the disease can be followed by post-infectious sequelae in some patients. Prevention of Lyme borreliosis primarily involves the avoidance of tick bites by personal protective measures.
EM or borrelial lymphocytoma: Doxycycline (DOC) or amoxicillin or cefuroxime axetil
Arthritis: Oral doxycycline, amoxicillin or cefuroxime axetil
Neuroborreliosis, recurrent arthritis and heart involvement: Ceftriaxone, cefotaxime or penicillin G
ACA: Amoxicillin, doxycycline, ceftriaxone, cefotaxime and penicillin G
Tick removal (if still present)
Characterized by complaints and symptoms persisting more than 6 months after proper Lyme borreliosis treatment.