Diagnosing Lyme in Denmark
By Linda on Dec 10, 2010 in Infections
Excerpt:
RESULTS: A total of 4,664 patients were tested. The IgM and IgG
seropositivity rates were 9.2% and 3.3%, respectively.
Questionnaires from 2,643 (57%) patients were available for
analysis. Erythema migrans (EM) was suspected in 38% of patients,
Lyme arthritis/disseminated disease in 23% and early
neuroborreliosis in 13%. Age 0-15 years and suspected EM were
significant predictors of IgM seropositivity, whereas suspected
acrodermatitis was a predictor of IgG seropositivity. LB was
suspected in 646 patients with arthritis, but only 2.3% were IgG
seropositive. This is comparable to the level of seropositivity
in the background population indicating that Lyme arthritis is a
rare entity in Denmark, and *the low pretest probability should
alert general practitioners to the possibility of false positive
LB serology*.
Significant predictors for treating the patient were a reported
tick bite and suspected EM.CONCLUSIONS: A detailed description of the utilization of
serology for Lyme borreliosis with rates of seropositivity
according to clinical symptoms is presented. Low rates of
seropositivity in certain patient groups indicate a low pretest
probability and there is a notable risk of false positive
results. 38% of all patients tested were suspected of EM,
although this is not a recommended indication due to a low
sensitivity of serological testing.
