Tick bites and Lyme disease in an endemic setting: problematic use of serologic testing and prophylactic antibiotic therapy.
BACKGROUND
The use of serologic testing to diagnose Lyme disease (LD) is a source of controversy. Expert recommendations also discourage the routine use of antibiotic therapy for prophylaxis of LD following tick bites, but the extent to which physicians in endemic areas have adopted these recommendations is not known.


OBJECTIVE
To assess the pattern of use of serologic testing and antibiotic therapy for tick bites and LD and associated charges for management in an endemic area.


METHODS
Active surveillance of patient-physician encounters for tick bites and LD.


METHODS
Primary care practices on the Eastern Shore of Maryland.


METHODS
Consecutive sample of 232 patients with tick bites, LD (defined by physician diagnosis in medical record), and suspected LD (physician notation of possible, but not definite LD) seen in 1995.


METHODS
Serologic testing for LD, test results, antibiotic therapy, and direct costs of management.


RESULTS
Surveillance identified 142 patients (61.2%) with diagnoses of tick bites, 40 patients (17.2%) with LD, and 50 patients (21.6%) with suspected LD. Of the 142 patients seen for tick bites, 95 (67%) underwent serologic testing for LD. Of these, 93 patients had initial negative or equivocal results; 24 (26%) of the 93 had convalescent testing, with 1 seroconversion. Seventy-eight patients (55%) with a diagnosis of tick bite received antibiotic therapy. No patients with tick bite developed clinical LD. Serologic testing for LD was performed for 36 patients (90%) with a diagnosis of LD and 46 patients (92%) with suspected LD. In most cases, antibiotics were prescribed before serologic test results became available. Convalescent testing was not performed for 37 (86%) of the 43 patients with suspected LD who had initial negative or equivocal results. Of these 37 patients, 25 (68%) did not receive antibiotic therapy. Direct charges for treatment of these 232 patients totaled $47 595, one third of which was attributable to serologic testing. A total of 32% of direct charges were for patients with tick bites, 48% were for patients with LD, and 20% were for patients with suspected LD.


CONCLUSIONS
In this setting, most patients consulting physicians for tick bites received prophylactic antibiotic therapy of unproven efficacy and underwent unnecessary, costly serologic testing. Despite almost universal use in this study, serologic testing for LD did not appear to influence treatment of patients diagnosed as having LD.
Fix
A D
AD
Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore 21201, USA. afix@epin.ab.umd.edu
Strickland
G T
GT
Grant
J
J
D000818:Animals; D019072:Antibiotic Prophylaxis / Q000191:economics / Q000706:statistics & numerical data*; D001733:Bites and Stings / Q000628:therapy*; D006801:Humans; D008193:Lyme Disease / Q000175:diagnosis / Q000517:prevention & control*; D008396:Maryland; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D012424:Rural Population; D012698:Serologic Tests / Q000191:economics / Q000706:statistics & numerical data*; D013987:Ticks