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.
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.
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
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
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.
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.
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.
- 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
- 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 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.
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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