Basics
Description
Multisystemic illness caused by the spirochete Borrelia burgdorferi, carried by the deer tick
Epidemiology
- Can affect people of all ages, but 1/3 " 1/2 of all cases occur in children and adolescents
- Male/female ratio: 1:1 to 2:1
- Onset most often in summer months
- Although Lyme disease can be found anywhere, the majority of the cases in the United States are found in Southern New England and the mid-Atlantic states. It is also seen frequently in California, Minnesota, and Wisconsin.
Prevalence
Has become most common tick-borne disease in the United States, with 29,959 confirmed cases reported in 2009
Risk Factors
Genetics
Chronic Lyme arthritis seems to be associated with increased incidence of HLA-DR4 and less so with HLA-DR2.
Pathophysiology
B. burgdorferi is injected into skin with saliva during bite of Ixodes tick. Spirochetes first migrate within skin, forming the typical rash, erythema migrans. Spirochetes then spread hematogenously to other organs, including heart, joints, and nervous system.
Etiology
The tick-borne spirochete B. burgdorferi
Commonly Associated Conditions
The same ticks that transmit Lyme disease can also transmit Ehrlichia and Babesia, so infections with those spirochetes can occur simultaneously.
Diagnosis
History
- Tick bite
- History of tick bite can only be elicited in 1/3 of patients with Lyme disease
- Most people with tick bites do not develop Lyme disease.
- Even in endemic areas, risk of developing Lyme disease after tick bite is <5%.
- Rash
- 50 " 80% will have or will recall the typical rash
- Rash is not painful or pruritic but feels warm.
- Other symptoms
- Many patients will complain of fatigue, headaches, fevers, chills, myalgias, conjunctivitis, and arthralgias early on.
- Joint pain
- Many patients will complain of painful joints early on and later will develop joint swelling.
- Signs and symptoms
- Skin: erythema migrans (typical rash)
- Starts as red macule or papule and then expands to annular lesion up to 30 cm in diameter with partial central clearing
- The lesion is usually painless and lasts 4 " 7 days.
- Musculoskeletal
- Early on, patient may experience myalgias, migratory joint pain (often without frank arthritis), and painful tendons and bursae.
- Weeks to months later, 60% of untreated patients will develop monoarticular or pauciarticular arthritis of large joints, especially knees.
- Joint fluid can have WBC count anywhere from 500 " 110,000 cells/mm3 and cells are mostly neutrophils.
- Neurologic
- Several weeks after initial rash, 14% of untreated patients will develop neurologic symptoms including aseptic meningitis, cranial nerve palsies (especially facial nerve palsies), mononeuritis, plexitis, or myelitis.
- Months to years later, chronic neurologic symptoms may occur, including a subtle encephalopathy: memory, mood, and sleep disturbances.
- Significant fatigue can occur early or late in the course of Lyme disease.
- Cardiac
- Several weeks after initial rash, ’ Ό5% of untreated patients develop cardiac disease.
- Most common cardiac lesion is atrioventricular block (primary, secondary, or complete).
- Pericarditis, myocarditis, or pancarditis can also develop.
Physical Exam
- May be completely normal early in course of disease
- Rash of erythema migrans, if seen, is virtually pathognomonic for Lyme disease.
- If patient does not have the rash, no physical finding exists that gives definitive diagnosis of Lyme
- Patient may have arthritis, Bell palsy, a cranial nerve palsy, conjunctivitis, or an irregular heartbeat.
Diagnostic Tests & Interpretation
Lab
Initial Lab Test
- Enzyme-linked immunosorbent assay (ELISA)
- Can detect antibodies to B. burgdorferi several weeks after tick bite. However, it has relatively high false-positive rate and occasionally false-negative results. It remains positive for years after treatment.
- Western blot analysis
- Much more specific. After 4 " 8 weeks of infection, ≥5 of the following IgG bands must be present for test to be positive: 18, 21, 28, 30, 39, 41, 45, 58, 66, and 93 kd. During first 2 " 4 weeks of infection, 2 IgM bands may establish diagnosis, but false-positive IgM blots are common.
- Positive ELISA with negative Western blot:
- Usually means patient does not have Lyme disease and ELISA was a false-positive, but false-positive IgM blots are common.
- Polymerase chain reaction (PCR)
- PCR testing may be done with synovial tissue or fluid or with CSF. Positive PCR indicates active disease, but negative result does not rule out Lyme.
- Urine tests for Lyme disease have been shown to be very inaccurate and should not be used.
Differential Diagnosis
- Viral arthritis/arthralgias
- Septic arthritis
- Juvenile idiopathic arthritis
- Postinfectious arthritis
- Fibromyalgia syndrome
- Systemic lupus erythematosus
- Pitfalls
- Incorrect diagnosis: Many patients with vague systemic complaints (fatigue, headaches, arthralgias) are incorrectly diagnosed with Lyme disease, even though their Lyme tests are negative (or ELISA mildly positive and Western blot negative).
- These patients are then treated with multiple courses of oral antibiotics; if they do not respond, they are often treated with IV antibiotics, sometimes for prolonged periods.
- This situation delays diagnosing true problem and subjects patients to unnecessary risks of long-term antibiotic use and occasionally of central venous lines.
Treatment
Medication
- Oral antibiotics
- Initial therapy for early Lyme disease
- Specific therapies
- Patients >8 years old: doxycycline is drug of choice.
- Younger children or people who do not tolerate tetracyclines: Amoxicillin or cefuroxime is preferred, but penicillin V is also acceptable.
- Penicillin-allergic patients: Erythromycin may be used but is less effective.
- Duration of therapy
- Patients with only skin rash: 14 " 21 days of oral antibiotics usually sufficient
- If other symptoms present: 21 " 28 days recommended
- IV antibiotics
- Become necessary for
- Persistent arthritis unresponsive to oral medications
- Severe carditis
- Neurologic disease (other than an isolated 7th-nerve palsy)
- Specific IV therapies
- Ceftriaxone: drug of choice
- Penicillin V: may also be used
- Duration of therapy: 14 " 21 days
- Prevention
- Some studies suggest that a single dose of doxycycline after tick bite will prevent Lyme disease.
- Protective clothing, tick repellants, and checking daily for ticks are good preventive measures.
Ongoing Care
Prognosis
- In general, it is much better for children than for adults. Only 2% of children have chronic arthritis at 6 months.
- Most of the cardiac manifestations will disappear with or without treatment in a short time (3 " 4 weeks) but may later recur. Severe cardiac involvement rarely may be fatal.
Complications
- Chronic arthritis occurs in ’ Ό2% of children.
- Other complications arise from treatment, such as
- Cholecystitis secondary to treatment with ceftriaxone
- Infections from indwelling catheters used for IV antibiotics
- Some patients develop what is thought to be a post " Lyme disease syndrome. This syndrome is not well defined and is very controversial. It often consists of arthralgias and fatigue but may include paresthesias and cognitive complaints. Prolonged antibiotics have not been shown to be helpful. Some of these patients present with a fibromyalgia-like syndrome and improve with physical therapy.
Additional Reading
- Bunikis J, Barbour AG. Laboratory testing for suspected Lyme disease. Med Clin North Am. 2002;86(2):311 " 340. [View Abstract]
- Feder HM Jr. Lyme disease in children. Infect Dis Clin North Am. 2008;22(2):315 " 326, vii. [View Abstract]
- Hayes E. Lyme disease. Clin Evid. 2002:652 " 664. [View Abstract]
- Huppertz HI. Lyme disease in children. Curr Opin Rheumatol. 2001;13(5):434 " 440. [View Abstract]
- Nachman SA, Pontrelli L. Central nervous system Lyme disease. Semin Pediatr Infect Dis. 2003;14(2):123 " 130. [View Abstract]
- Shapiro ED, Gerber MA. Lyme disease: fact versus fiction. Pediatr Ann. 2002; 31(3):170 " 177. [View Abstract]
- Steere AC. Lyme disease. N Engl J Med. 2001;345(2):115 " 125. [View Abstract]
- Weinstein A, Britchkov M. Lyme arthritis and post-Lyme disease syndrome. Curr Opin Rheumatol. 2002;14(4):383 " 387. [View Abstract]
Codes
ICD09
- 088.81 Lyme Disease
- 711.80 Arthropathy associated with other infectious and parasitic diseases, site unspecified
- 320.7 Meningitis in other bacterial diseases classified elsewhere
ICD10
- A69.20 Lyme disease, unspecified
- A69.23 Arthritis due to Lyme disease
- A69.21 Meningitis due to Lyme disease
- A69.22 Other neurologic disorders in Lyme disease
- A69.29 Other conditions associated with Lyme disease
SNOMED
- 23502006 Lyme disease (disorder)
- 33937009 Lyme arthritis (disorder)
- 230150008 Meningitis in Lyme disease (disorder)
- 230605007 Lyme mononeuritis multiplex (disorder)
FAQ
- Q: What does the deer tick look like?
- A: The deer tick is flat, very small (about the size of a pin head), and has 8 legs. The adult male is black, and the female is red and black. They can grow to 3 times their normal size when they are engorged with blood.
- Q: Do all bites from infected deer ticks cause Lyme disease?
- A: No. Even infected ticks will not cause Lyme disease if they are attached to the skin for a short period of time. If the tick is attached for <24 hours, the chances of transmitting the disease are exceedingly low. The longer the tick is attached, the higher the probability of disease transmission.
- Q: Should all patients be retested for Lyme disease after a full course of treatment?
- A: No. Lyme titers and the Western blot will remain positive for years after adequate treatment for Lyme disease. If the patient 's symptoms have resolved, there is no point in rechecking the titer. If the patient is still symptomatic, titers and a Western blot may be checked before starting IV antibiotic therapy to look for a rising titer and to be sure the patient truly has Lyme disease. If symptoms remain after IV therapy, other diagnoses should be considered.
- Q: Should patients with nontraumatic Bell palsy be tested for Lyme disease?
- A: Bell palsy is seen in association with Lyme disease infections. It is a reasonable indication for testing for Lyme disease.