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Image of an Ixodes ricinus tick on skin from Wikimedia Commons | Jørn Gabrielsen. [Creative Commons Attribution License 3.0 Unported (CC by 3.0).]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Lyme disease remains the most common vector-borne infection in the United States,[1] usually caused by the spirochetal organism Borrelia burgdorferi. Disease is transmitted to humans and animals by Ixodes ticks. The nymphs of these vectors are relatively hard and less than 2 mm in size, so they look like dirt or environmental particles and are difficult to see. Adults are larger and even harder, so they are more likely to be identified and removed rapidly. Ticks must remain attached for 36-48 hours before they can transmit the bacterial pathogen, which is a very important factor for prevention.

Top images from the Centers for Disease Control and Prevention (CDC) | James Gathany. [Public domain.] Bottom left image from the CDC. [Public domain.] Bottom right image from Wikimedia Commons | Lamiot. [CC by-SA 3.0.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Lyme disease is endemic in North America, Europe, and Asia. The distribution of the tick vectors accounts for its incidence. Ixodes scapularis(top left) is the principal vector in the Northeast and Central United States and Canada, whereas Ixodes pacificus(top right) is more common on the Pacific coast. Ixodes ricinus(bottom left) is the main vector in Europe (a male I ricinus tick attached to the ventral surface of a female is shown). The vector in Asia is the taiga tick, Ixodes persulcatus (bottom right).

In order of frequency in the United States per 100,000 population, the highest incidence of Lyme disease is in Maine, Vermont, Pennsylvania, Rhode Island, and Connecticut.[2]

Darkfield microscopy of Borrelia burgdorferi (400x magnification). Image from the CDC. [Public domain.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Lyme disease is primarily caused by B burgdorferi sensu lato, which has three genospecies as follows: B burgdorferi sensu stricto, B garinii, and B afzelii. In European patients with erythema migrans, B afzelii accounts for 80% of lesions and B garinii, 15%.[3]

Due to genomic variation, these genospecies are associated with different clinical presentations. Infection with B burgdorferi sensu stricto has a particular predilection to affect joints. B afzelii most often infects the skin but may persist there, causing various cutaneous manifestations including acrodermatitis chronica atrophicans. B garinii has neurotropism and accounts for most cases of lymphocytic meningoradiculitis (Bannwarth syndrome) and encephalitis.

The life cycle of a deer tick from Wikimedia Commons | Cfhand15. [CC BY-SA 4.0.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

The infectious cycle of B burgdorferi and their tick vectors spans over 2 years, involving colonization of animals, infection of Ixodes ticks, and then transmission to a broad range of mammalian hosts, including humans.[4] The larvae feed on a variety of small animals, primarily the white-footed mouse.

The next spring, the larvae emerge as nymphs. Nymphs molt into adults the following fall and feed once on larger animals, with the white-tailed deer the preferred host. Ticks carry B burgdorferi organisms in their midgut, translocating them from the gut to the salivary glands and transmitting them to humans by bites.

Erythema migrans initial rash occurring 3-14 days after the tick bite. Image courtesy of Russell Steele, MD.

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

The clinical manifestations of Lyme disease generally follow three stages of progression: early localized, early disseminated, and chronic disseminated. Primary or early localized infection occurs within 30 days of the tick bite. Most patients present with a characteristic target-appearing rash (erythema migrans) at the site of the tick bite 3-14 days after the tick attaches and bites.[5]

Nonspecific flu-like symptoms may include fatigue, myalgia, and fever. Treatment at the onset of the rash prevents progression of disease.

It should be emphasized that most tick bites produce a circular area of erythema at the site of the bite that fades 1-3 days after the bite; this is not erythema migrans.

Image from Aucott J, Morrison C, Munoz B, Rowe PC, Schwarzwalder A, West SK. BMC Infect Dis. 2009;9:79. [Open access.] PMID: 19486523; PMCID: PMC2698836. [CC by 2.0.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Stage 2 or early disseminated disease occurs weeks to months after the bite. Multiple 3-8–cm erythematous patches (shown) may be seen, although musculoskeletal and neurologic symptoms are more common.[6] The dermatologic inflammatory response to B burgdorferi likely explains the multiple lesions of erythema migrans, as almost all patients with multiple lesions are seropositive, regardless of the duration of the disease.

Antibodies against this spirochetal organism cross-react with neural and connective tissues. This molecular mimicry likely generates an autoimmune inflammatory reaction, the probable pathophysiology of the late manifestations of disease.

Image from the CDC. [Public domain.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

The best diagnostic test for Lyme disease is documented erythema migrans rash, particularly in endemic regions, and with recent tick exposure. These patients require immediate antibiotics. When the diagnosis is unclear, serologic testing is recommended using either concurrent or the sequential two-tier procedure.[7]

In July 2019, the US Food and Drug Administration (FDA) approved the use of concurrent or sequential enzyme immunoassay (EIA) testing for diagnosis of Lyme disease, guided by data from clinical studies showing that this alternative approach (the modified two-tier test), is as accurate as testing with EIA or immunofluorescence assay (IFA) plus Western blot.

  • EIA or IFA - Total Lyme titer or immunoglobulin G (IgG) and IgM titers
  • Western blot testing is rarely necessary but may be considered if EIA or IFA test results are positive or equivocal. If signs and symptoms have been present for 30 days or less, both IgM and IgG Western blot testing are performed; if signs and symptoms have been present for more than 30 days, only IgG Western blot testing is necessary. Of note, serologic testing is difficult to interpret and has relatively low sensitivity and specificity.

Most clinicians consider oral doxycycline the preferred treatment for early Lyme disease. Image from National Institute of Allergy and Infectious Diseases via Flickr. [CC by 2.0.]

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Recommended treatment of Lyme disease is as follows:

  • Adult patients with early localized or early disseminated Lyme disease associated with erythema migrans: Doxycycline, amoxicillin, or cefuroxime axetil
  • Children under 8 years and pregnant or nursing individuals with early localized or early disseminated Lyme disease: Amoxicillin or cefuroxime axetil
  • Neurologic Lyme disease: Intravenous (IV) penicillin, ceftriaxone, or cefotaxime; oral doxycycline, when not contraindicated, in patients with Lyme-associated meningitis, facial nerve palsy, or radiculitis

Adults and children with early Lyme disease should be treated for 10-14 days.[1,8] For adults with associated erythema migrans, a 10-day course of doxycycline or a 14-day course of amoxicillin or cefuroxime axetil appear to be equally effective, although there are more published data for doxycycline. Pregnant and nursing people should avoid doxycycline. Children younger than 8 years can receive doxycycline for up to 21 days without teeth staining[9]; amoxicillin or cefuroxime axetil also are recommended.[9]

For neurologic disease including meningitis, facial nerve palsy, or radiculitis, IV therapy with penicillin, ceftriaxone, or cefotaxime are effective.

Infant with Lyme arthritis and the erythema migrans rash near the site of joint involvement. Image courtesy of Russell Steele, MD.

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Lyme Arthritis

In patients with late disease, the most common manifestation is arthritis, involving primarily large joints, especially the knee. Warmth, swelling from effusion, and limited range of motion help distinguish arthritis from simple arthralgia.

Patients with delayed treatment are more likely to develop acute arthritis, chronic musculoskeletal symptoms, and difficulties along with memory, concentration, and chronic fatigue. These can be debilitating and difficult to manage. The pathogenic mechanism for chronic arthritis is thought to be immunologic rather than active infection. This condition is more prevalent among those with human leukocyte antigen (HLA)-DR2, HLA-DR3, or HLA-DR4 allotypes.

The arthritis resists antibiotic treatment but typically responds to nonsteroidal anti-inflammatory drugs (NSAIDS) and local symptomatic treatment, usually with gradual, but complete, resolution.[10-13]

Recommended treatment of Lyme arthritis is as follows:

  • Oral antibiotics for 28 days
  • Retreatment with oral antibiotics for mild residual joint swelling
  • Retreatment with IV antibiotics for refractory cases
  • Oral antibiotics for another month in patients with positive polymerase chain reaction (PCR) of synovial fluid
  • NSAIDs in patients with negative PCR, supplemented, if necessary, with hydroxychloroquine
  • Consideration of arthroscopic synovectomy in patients unresponsive to symptomatic therapy
Image courtesy of Medscape.

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Treated early, the prognosis for Lyme disease is excellent. Mortality is very low, with most reported fatal cases in those with severe comorbidity(ies). Cardiac involvement is rarely chronic, but patients with complete third-degree heart block (shown) often require insertion of a temporary pacemaker and, rarely, a permanent pacemaker.[3,4] Symptoms may linger for more than 6 months for 10-20% of patients.[4,12,13]

Posttreatment Lyme disease syndrome may occur and include cognitive disturbances, fatigue, joint or muscle pain, headaches, hearing loss, vertigo, mood disturbances, paresthesia, and difficulty sleeping. No evidence suggests that prolonged antibiotic therapy is effective for this condition.

Lyme carditis may be treated with either oral or parenteral antibiotic therapy for 14 days (range, 14-21 days). Hospitalization and continuous monitoring, with consideration for temporary pacing, are advisable for patients with any of the following:

  • Associated symptoms (eg, syncope, dyspnea, or chest pain)
  • Second-degree or third-degree atrioventricular block
  • First-degree heart block with prolonged PR interval to more than 300 milliseconds (the degree of block may fluctuate and worsen very rapidly in such patients)
Tick removal using forceps as close to the skin as possible, employing slow, gentle traction. Image courtesy of Medscape.

Lyme Disease

Russell W Steele, MD | June 15, 2022 | Contributor Information

Education of parents and children who live in endemic areas of Lyme disease is essential. Anticipatory guidance should focus on preventive measures, including the use of insect repellents (30% diethyltoluamide [DEET]), wearing long-sleeve shirts and long pants, and examining children daily for ticks, keeping in mind that the nymphs are tiny, less than 2 mm, and tend to be on the child's head.

The preferred method for tick removal is performed with fine-tipped forceps.[11] When removing, wear gloves to avoid possible infection. Grasp the tick as close to the skin surface as possible, clamping on the mouth parts, and pull upward with steady, gentle traction. Do not twist or jerk the tick, because this may cause the mouth parts to break off and remain in the skin.

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