Two-tiered Testing Decision Tree
About This Figure
The Two-tier Testing Decision Tree describes the steps required to properly test for Lyme disease. The first required test is the Enzyme Immunoassay (EIA) or Immunofluorescence Assay (IFA). If this test yields negative results, the provider should consider an alternative diagnosis; or in cases where the patient with has had symptoms for less than or equal to 30 days, the provider may treat the patient and follow up with a convalescent serum. If the first test yields positive or equivocal results, two options are available: 1) If the patient has had symptoms for less than or equal to 30 days, an IgM Western Blot is performed; 2) if the patient has had symptoms for more than 30 days, the IgG Western Blot is performed. The IgM should not be used if the patient has been ill for more than 30 days.