2. DEFINITION
● A skin lesion that typically begins as a red macule or papule and
expands over a period of days to weeks to form a large round lesion,
often with partial central clearing. A single primary lesion must reach
≥5 cm in diameter.
● Secondary lesions also may occur. Annular erythematous lesions
occurring within several hours of a tick bite represent hypersensitivity
reactions and do not qualify as EM. The diagnosis of EM must be
made by a physician.
3. Introduction
● In 1912, a Swedish dermatologist, Arvid Afzelius, first described the skin
eruption of Lyme disease, erythema chronicum migrans (ECM), which is
now referred to as Erythema Migrans (EM).
● Another dermatological manifestation of Lyme disease, Acrodermatitis
chronica atrophicans (ACA), was reported by a German physician, Alfred
Buchwald as early as in 1883.
● Lyme disease is named after a town in Connecticut, USA, where the
initial cluster of children with arthritis was reported in 1975. The generic
species is B. burgdorferi (sensu lato).
4. ● The generic species is B. burgdorferi (sensu lato).
● Several well-characterized groupings exist within this species.
Three groups are well established, including
❖ B. burgdorferi sensu stricto,
❖ B. garinii and
❖ B. afzelii.
5. Etiology
● Erythema migrans (EM) is the most characteristic aspect of Lyme
disease. It may also occur as an isolated phenomenon, without the other
features of Lyme disease.
● Both Lyme disease and erythema migrans, which means “chronic
migrating red rash”, are caused by the spirochete Borrelia burgdorferi.
● They are transmitted by the bite of certain Ixodes ticks which have B.
burgdorferi in their gastrointestinal system.
6. ● Ixodes scapularis (I. dammini) is the vector in the northeastern and
upper midwestern United States, whereas I. pacificus serves as the
vector in the northwestern United States.
● The vector in Asia is the taiga tick, I. persulcatus. Other tick species
(e.g., Amblyomma americanum) and insects can carry B. burgdorferi,
but in most cases, the disease is caused by bites by Ixodes ticks.
7. CLINICAL FEATURES
● Some of the clinical manifestations are caused by active infection by the
spirochete; others may be induced by immunopathogenetic mechanisms.
● The organism has a distinct predilection for skin, heart, central nervous
system (CNS), joints and eyes. However, any system of the body can be
affected once it enters into circulation.
● During early hematogenous dissemination, spirochetes have been
observed in bone marrow, spleen, lymph nodes, liver, testes, and
placenta.
8. ❖ The clinical manifestations can be categorized into three stages of disease
progression:
1.Early localized,
2.Early disseminated and
3.Chronic disseminated.
❖ All phases can be cured with antibiotic therapy. In about half of untreated
patients, the disease progresses to the disseminated stage.
❖ The average interval between the time of the infectious bite and the
appearance of the skin lesion is approximately 9 days (ranging from 1–28
days).
9.
10. ● The lesion starts as a small papule that turns into a slowly enlarging ring
, whereas the central erythema gradually disappears and leaves a
surface that is usually normal but may be slightly bluish.
● The ring remains flat, blanches with pressure and does not
desquamate, vesiculate, or have scales at the periphery as ringworm
does.
● The lesion is usually circular but a distortion of the configuration may
occur when the ring spreads over the skinfolds.
14. ● The lesion may have a slightly raised border. Burning or itching can be felt
by certain patients.
● Over several days, the erythema expands centrifugally away from the
central bite punctum, forming a broad, round-to-oval area measuring 5–10
cm.
● It clears centrally within a week, leaving a red 1–2 cm ring that advances
for days or weeks and may reach a diameter of 50 cm.
● Multiple concentric rings are observed in many cases.
● Tenderness and very mild itching are present. EM fades even in untreated
patients within 3–4 weeks
15. DIAGNOSIS
1.Confirmed
• A case of EM with a known exposure.
• A case of EM with laboratory evidence & without a known exposure.
• A case with at least one late manifestation +/- that has laboratory evidence of
infection .
2. Probable
• Any other case of physician-diagnosed Lyme disease that has laboratory
evidence of infection.
16. 3. Suspected
• A case of EM where there is no known exposure* and no laboratory
evidence of infection.
• A case with laboratory evidence of infection but no clinical information
available.(e.g. a laboratory report)
17. ● Although the spirochete may grow in the laboratory, cultures are
rarely positive hence not performed.
● The serological tests are the mainstay of diagnosis.
● The main available tests are
1. ELISA or Enzyme immunoassay (EIA),
2. Immunofluorescent assay (IFA) and
3. Western immunoblot (WB) testing for detection of IgG or IgM
antibodies.
18. ● Serologic testing is recommended only when the clinicians suspect
that there is at least a 20% chance of the patient having active
Lyme disease.
● False positivity even among healthy populations of nonendemic
regions is quite common.
● Normal levels vary depending on the laboratory assay as follows:
ELISA: less than 1:8;
Western blot: Nonreactive.
19. ● Though a single IgG western blot testing is adequate for surveillance
purpose, two-tier testing consisting of an initial positive or equivocal
EIA/ IFA followed by WB test is recommended for diagnosis of Lyme
disease.
20. ● Many patients with active or recent infections do not have detectable
antibodies to B. burgdorferi (Bb) in a single specimen. It takes about
2–4 weeks to develop antibodies to Bb and detectable anti Bb
antibodies may diminish or never develop in patients treated with
antibacterial drugs.
● Both IgM and IgG antibodies against Bb may persist from months to
years after successful treatment of Lyme borreliosis.
21. TREATMENT
● The recent recommendations for adults in the early localized forms of
illness are doxycycline (100 mg b.i.d. for 14 days).
● Amoxycillin 500 mg thrice daily for 14 days or cefuroxime 500 mg twice
daily for 14 days may be the next option where doxycycline is
contraindicated, e.g., in pregnancy and children below 8 years.
● Amoxicillin is used in children (20–40 mg/kg per day). One trial showed
that cefuroxime 500 mg b.i.d. or doxycycline 100 mg b.i.d. can achieve
93% and 88% cure or improvement, respectively. However, cefuroxime
caused diarrhea more commonly and is more expensive.
22. ● In Disseminated disease with neurologic or cardiac involvement
Injection Ceftriaxone 2 g IV daily for 14–28 days or Penicillin G 18–24
million units daily (in divided doses every 4 hour) for 14–28 days have
been recommended.
● Oral Erythromycin (250 mg four times daily for 14 days) or Azithromycin
(500 mg daily for 7 days) can be used in early localized disease where
tetracyclines and β-lactam antibiotics are contraindicated.
24. PREVENTION
● The insect-repellent diethyltoluamide (DET) used on the skin
repels a variety of insects including ticks.
● Permethrin as an aerosol is effective as a clothing spray for
protection against ticks.
