Overall, 94% of Lyme cases are reported from Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Jersey, New Hampshire, New York, Pennsylvania, Virginia, and Wisconsin. Although Lyme disease is the most common vectorborne disease in the United States, the diagnosis is complicated by two potential stages of illness with variable presentations involving dermatologic, musculoskeletal, neurologic, and cardiac findings.
The localized stage of Lyme disease is most likely to present in the summer months 3–30 days after a tick bite. The hallmark of localized Lyme disease is erythema migrans (EM) (Figure 5-3). EM is typically at the site of prior tick attachment, often presenting for 7 days after the initial bite. It is characterized by an erythematous, ring or target macular lesion, typically measuring ≥5 cm. Rashes at the site of tick bites in the first 48 hours after a bite are typically local reactions and not indicative of TBD. EM is diagnostic of Lyme disease, and its presence is the only instance in which confirmatory testing is not necessary. This Lyme rash can present alternatively as a nontargetoid bluish lesion, as a rash with central crusting and no clearing, or as multiple red lesions with dusky centers known collectively as disseminated erythema migrans, which is indicative of disease spread. 70-80% of patients with Lyme disease present with EM, which typically resolves within 3–4 weeks without treatment. Along with EM, the most common presenting symptoms of Lyme are fever, headache, myalagias, malaise, and fatigue, which are mostly consistent with a flulike illness but lack upper respiratory or gastrointestinal symptoms (Table 53-2).
Table 53-2.Diagnosis of tickborne diseases. ||Download (.pdf) Table 53-2.Diagnosis of tickborne diseases.
|Disease ||Incubation ||Signs and Symptoms ||General Labs ||Confirmatory Labs |
|Localized Lyme disease ||3–30 days ||Erythema migrans (EM), flulike illness ||Elevated ESR (typically <80), mild LFT elevation ||Not typically applicable; see below; EM diagnostic |
|Disseminated Lyme disease ||Month(s) after bite ||Disseminated EM, large-joint arthritis, CN palsies, meningitis ||CSF lymphocytic pleocytosis, elevated ESR/CRP ||IgG/IgM; if +antibodies, then Western blot confirmation |
|RMSF ||2–14 days ||Fever, maculopapular rash 2–5 days after fever, petechiae after day 6, severe headache, AMS, meningismus ||Thrombocytopenia, mild LFT elevation, hyponatremia || |
IgG + 7–10 days after onset of illness, fourfold increase after 2–4 weeks
IgM false + common, early disease seronegative
|Ehrlichiosis ||7–14 days ||Fever, headache, malaise, rash in 60% of children ||Mild anemia, thrombocytopenia, leukopenia, elevated LFTs || |
Ehrlichia IgG + 1 week after onset of illness, fourfold increase after 2–4 weeks
+PCR before abx
|HGA ||7–14 days ||Fever, headache, myalgias ||Mild anemia, thrombocytopenia, leukopenia, elevated LFTs || |
IgG + 1 week after onset of illness, fourfold increase after 2–4 weeks
+PCR before abx
|Babesiosis ||7 days–2+ months ||Fever, malaise, dark urine, nausea ||Hemolytic anemia, thrombocytopenia, elevated BUN/Cr ||Blood smear ID of protozoa, +PCR, antibody testing |
The disseminated stage of Lyme disease typically occurs weeks after the initial infection. This can be manifested as disseminated EM as well as the persistence of flulike symptoms. Disseminated Lyme should be suspected in patients presenting in late summer/fall with aseptic meningitis, cranial nerve palsies (particularly Bell palsy), atrioventricular block, myocarditis/pericarditis, migratory joint pain, and large joint monoarthritis or oligoathritis. Late- stage Lyme can manifest with one or more of these symptoms, and in endemic areas it is important to include TBD in the differential for any of these symptoms so that proper laboratory workup can be performed (Table 53-2).
Laboratory evaluation in localized Lyme is often nonspecific. An elevated erythrocyte sedimentation rate, elevated liver enzymes, and hematuria or proteinuria can be seen. If a patient is suspected to have aseptic meningitis presenting with fever and headache, the cerebrospinal fluid (CSF) can demonstrate elevated lymphocytes/lymphocytic predominance, mild increase in protein, and normal glucose. The CDC has two accepted diagnosis methodologies for Lyme disease: EM and the presence of at least one sequela of late-stage disease and confirmatory testing. Serologic antibody testing is the laboratory diagnosis of choice. However, antibody testing is not helpful for early disease, as IgM does not develop until 2–4 weeks after initial disease and IgG typically takes longer than 4 weeks to develop. When ELISA testing is ordered, positive or indeterminate tests are typically followed by Western blot confirmation as false positives are common. Lyme disease–specific antibodies from CSF may be helpful in diagnosing cases of meningitis (Table 53-2).
Imaging studies may be useful in ruling out other etiologies when considering Lyme disease. The differential diagnosis should include other tickborne diseases, especially HGA, babesiosis, and Southern Tick-Associated Rash Illness (STARI). STARI is an emerging tick-borne disease with unknown etiology, but very similar presentation to early Lyme. At present the CDC recommends using the same antibiotics to treat STARI that are used to treat Lyme (Table 53-3). Non-tick related differentials for EM include local tick bite reaction, cellulitis, erythema multiforme, nummular eczema, granuloma annulare, contact dermatitis, and alternative arthropod bites. For late stage Lyme the differential includes juvenile idiopathic arthritis, rheumatoid arthritis, septic arthritis, gout, pseudogout, viral meningitis, multiple sclerosis, other etiologies of Bell palsy, and lymphoma.
Table 53-3.Treatment of tickborne diseases. ||Download (.pdf) Table 53-3.Treatment of tickborne diseases.
|Disease ||First-Line Antibiotics (Adults) ||First-Line Antibiotics (Children) ||Duration ||Alternative Regimens/Comments |
|Localized Lyme Diseasea || |
Doxycycline 100 mg PO BID, amoxicillin 500 mg PO TID
Cefuroxime 500 mg POD BID
|Doxycycline 4 mg/kg divided doses BID, amoxicillin 50 mg/kg divided doses TID, cefuroxime 30 mg/kg divided doses BID ||14 days, although can be extended to 21 days depending on case presentation ||Macrolides can be used for patients who are intolerant of antibiotics listed They are less effective; doxycycline 200 mg can be given as single-dose prophylaxis |
|Disseminated Lyme disease || |
Ceftriaxone 2 g IV once daily
Cefotaxime 2 g IV every 8 hours
Penicillin G 18–24 million units/day in 6 divided doses
Arthritis without CNS: treat with antibiotics for localized disease
CNS/carditis: ceftriaxone 50–75 mg/kg IV
Arthritis without CNS: treat with antibiotics for localized disease
CNS/carditis: 14–28 days
Arthritis without CNS: 28 days
Doxycycline 200–400 mg/day orally in 2 divided doses if unable to tolerate β-lactam antibiotics
Carditis patients should preferentially be treated with ceftriaxone
|RMSF ||Doxycycline 100 mg PO or IV BID ||Doxycycline 2.2 mg/kg per dose PO or IV BID ||At minimum 3 days after resolution of fever; minimum 5–7 days ||Use doxycycline if RMSF suspected in all cases, including children; other antibiotics increase likelihood of mortality |
|Ehrlichiosis/ HGA ||Doxycycline 100 mg PO or IV BID || ||At minimum 3 days after resolution of fever; minimum 5–7 days ||Rifampin is an alternative in special circumstances |
|Babesiosis || |
(1)Atovaquone 750 mg PO q12h +
azithromycin 500–1000 mg PO on day 1 and 250 mg once daily thereafter
(2) Clindamycin 300–600 mg IV q6h or 600 mg PO q8h + quinine 650 mg PO q6–8h
(1) Atovaquone 20 mg/kg PO q12h + azithromycin 10 mg/kg PO on day 1 and 5 mg/kg once daily thereafter
(2) Clindamycin 7–10 mg/kg IV or PO q6–8h + quinine 8 mg/kg PO q8h
|Treat for at least 7–10 days || |
Clindamycin plus quinine is the standard for severe babesiosis, but not as well tolerated
Treatment not recommended for asymptomatic patients
The treatment of Lyme disease is complicated by the local and disseminated stages. Treatment options for those presenting with erythema migrans are doxycycline, cefuroxime, and amoxicillin for a ≥14-day course. There is some evidence supporting doxycycline use for only 10 days. Intravenous dosing with cetriaxone, cefotaxime, and penicillin G is indicated in patients with central nervous system (CNS) and cardiac manifestations. Arthritis manifestations without CNS manifestations can be treated with the aforementioned oral medications for 28 days (Table 53-3).
Prognosis for Lyme is good, especially with early treatment. Even if disease progresses to disseminated stage, disability is uncommon. Treatment at any stage portends a high likelihood of symptom resolution, but lasting symptoms typically consist of arthralgias and/or sensory deficits (CN VII). Chronic Lyme disease is a separate entity with symptoms typically consisting of musculoskeletal pain and fatigue. Chronic or posttreatment Lyme continues to be an area of controversy. Studies are ongoing as to potential etiologies, but continued antibiotic treatment after resolution of active disease is not indicated.
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