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Delaware Health Alert Network #118

June 2, 2006 11:13 AM


Health Advisory
LYME DISEASE UPDATE - 2006

Delaware Division of Public Health (DPH) would like to update the medical community about Lyme disease in Delaware and provide information about incidence, symptomology, diagnostic testing, treatment and reporting.

Background

Lyme disease is the most commonly reported vectorborne disease in the United States. Delaware is among the top ten states for the highest Lyme disease incidence rates. Additionally, the incidence of Lyme Disease in Delaware has significantly risen over the past few years. During 2004, DPH confirmed 382 cases of Lyme disease. In 2006, the number of cases increased by 62% (620 new cases). New Castle County typically accounts for 55-67% of all cases---Kent County ranges from 15-26% and Sussex County 15-23%.

This rise in incidence can be partially explained by the implementation of a new electronic reporting system in which commercial laboratories (i.e., LabCorp, Quest) and hospitals automatically report all positive test results for diseases that are reportable by Communicable Disease Regulation. Additionally, DPH Epidemiology increased Lyme disease surveillance efforts and follow-up case reports with the reporting health care provider.

It is believed that Lyme disease remains largely underreported and undiagnosed throughout the state of Delaware, as well as nationally.

Symptomology

Lyme disease is caused by the bacterium Borrelia burgdorferi and is characterized by a distinctive skin lesion, systemic symptoms and neurological, rheumatological and cardiac involvement occurring in varying combinations over months to years. Early symptoms are intermittent and changing. The most clinically obvious sign of early disease is the erythema migrans skin lesion (EM, formerly known as 'erythema chronicum migrans'), which occurs in only 60-80% of patients. With or without EM, early systemic manifestations may include malaise, fatigue, fever, headache, stiff neck, myalgias, arthralgias and/or lymphadenopathy, which can easily mimic many conditions.

Within weeks to months, neurological abnormalities such as aseptic meningitis and cranial neuritis may develop including facial palsy, chorea, cerebellar ataxia, motor or sensory radiculoneuritis, myelitis and encephalitis. Symptoms fluctuate and may become chronic and include cardiac abnormalities and intermittent episodes of swelling and pain in large joints, especially the knees. Chronic arthritis often results.

Co-infection with other tickborne pathogens (i.e., Babesia, Ehrlichia) can alter the clinical appearance of Lyme disease and should be considered when ordering diagnostic testing and reviewing treatment options.

Diagnostics

Diagnosis of Lyme disease is largely clinical.

  • Standard laboratory testing utilizing Centers for Disease Control and Prevention (CDC) two-tiered approach using enzyme immunoassay (EIA) followed by a Western blot only when the EIA is positive, lacks sensitivity. There are many patients who test negative by EIA, yet have fully diagnostic Western blots. Serologic tests are poorly standardized and must be interpreted with caution. They are especially insensitive during the first weeks of infection and may remain negative in individuals that receive early antibiotic treatment. Test sensitivity may increase when the patient progresses to later stages, but some chronic Lyme disease patients may remain seronegative. EIA and/or Western blot can be performed on any sterile body fluid---not just serum.
  • Polymerase Chain Reaction (PCR): Although very specific, sensitivity is poor because B. burgdorferi causes deep tissue infection and is only transiently found in body humors. PCR has identified B. burgdorferi genetic material in synovial fluid, CSF, blood, urine, skin and other tissues. Just as in routine blood culturing, multiple specimens are collected to increase yield; a negative result does not rule out infection, but a positive one is significant. The usefulness of PCR in routine management of Lyme disease cases has yet to be verified.
  • Culture: Isolation from blood and tissue biopsies is difficult, but the biopsies of the EM lesions may yield the organism in 80% of cases or more.
  • Key point: Just because you cannot find evidence of Lyme disease in the laboratory, does not mean it is not there.

Treatment

It is easiest to cure early disease. The sooner treatment is begun after the start of infection, the higher the success rate. Undertreated infections will inevitably resurface with tremendous problems of morbidity and difficulty with diagnosis and treatment.

Specific treatment:

  • Adults - the EM stage is the easiest to treat and can usually be treated effectively with doxycycline 100mg twice daily or amoxicillin 500mg three to four times daily. For localized EM, 2 weeks of treatment may suffice, but should be based upon patient symptomology. For early disseminated infection, a minimum of 3-4 weeks is necessary and again, should be based on symptomology.
  • Children - under 9 years of age can be treated with amoxicillin, 50mg/kg/day in divided doses, for the same time period as adults, depending on symptoms.
  • Cefuroxime axetil or erythromycin can be used in those allergic to penicillin or who cannot receive tetracyclines.
  • Lyme arthritis can sometimes be treated with a 4 week course of oral agents. However, longer treatment, depending on symptoms is frequently necessary.
  • Some resilient cases are best treated with IV ceftriaxone, 2 grams daily, or IV penicillin, 20 million units in 6 divided doses, for 3-4 weeks, depending on symptoms.
  • Treatment failures occur with any of these regimens and retreatment may be necessary. Treatment is individual and longevity should be based upon patient symptomology.

Prevention

Prevention of Lyme disease and other tickborne diseases is best accomplished by reducing exposure to ticks. There are a number of things you can do to protect yourself and your property:

  • When outdoors, stay in open spaces or on well maintained trails. Ticks cannot jump, fly or descend from trees. A tick must come in actual contact with you in order to attach itself.
  • Clothe yourself protectively. When a tick attaches to you, it climbs upward. Tuck your pant legs into your socks or boots and your shirt into your pants. Light-colored clothing will help you to spot ticks more easily.
  • Spraying boots and clothing with repellents containing permethrin provides protection for days. Repellents containing DEET can be applied to the skin but last only a few hours before reapplication is necessary. Wear insect repellent containing less than 50 percent DEET for adults, less than 30 percent DEET for children. Do not overuse; application of large amounts of DEET on children has been associated with adverse reactions.
  • Keep your property clean and lawn mowed regularly. Leaf litter and brush should be removed as far away from the house as possible. Ticks tend to survive in the winter by hiding under leaf litter.
  • Perform frequent tick checks and properly remove attached ticks with tweezers.

Reporting

Lyme disease is a reportable condition and should be reported to DPH, Epidemiology. For questions, please call 888-295-5156.

Communicable Disease Regulations: http://www.state.de.us/research/AdminCode/title16/4000/4200/4202.shtml#TopOfPage

List of Notifiable Diseases and Reporting Requirements: http://www.dhss.delaware.gov/dhss/dph/dpc/rptdisease.html

CDC Lyme Disease Information: http://www.cdc.gov/ncidod/diseases/submenus/sub_lyme.htm

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