Category: Lyme Signs, Symptoms, & Diagnosis
What percent of cases of reasonably proven Lyme disease present without erythema migrans?
According to the Centers for Disease Control (2008), erythema migrans occurs in 60-80% of Confirmed cases. Thus, 20-40% of confirmed cases do not present with the characteristic Lyme rash. To be considered a Confirmed cases by CDC in the absence of a rash, a person has to have laboratory evidence of infection and at least one late manifestation of Lyme disease. Late manifestations of Lyme disease considered diagnostic are: joint swelling, Bells palsy or other specific signs of nervous system involvement, or specific cardiac conduction defects.
The CDC also has criteria for Probable case, defined as physician-diagnosed Lyme disease that has laboratory evidence of infection. Suspected cases without an EM are those with laboratory evidence of infection but no clinical information available.
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