Urinary antigen testing has not been proven to have diagnostic utility. Serologic studies are currently the only widely used laboratory diagnostic aid for Lyme disease. Clinicians should use clinical judgement in making a diagnosis of Lyme disease and use results of a two-step algorithm recommended by a national conference only as supporting evidence. A key element in the diagnosis is a history of outdoor activity in an area known to harbor Ixodes ticks. Assays should not be used to screen asymptomatic patients.
Simultaneous infections can occur with two or more tick-borne infections.
Such coinfections have been reported for Lyme disease and both human granulocytic ehrlichiosis and babesiosis. By treating stage 1 Lyme disease with antibiotics, one can reduce the likelihood that patients will develop later sequelae of Lyme disease. One should reevaluate the diagnosis and then consider repeating treatment if the patient's stage 1 symptoms do not resolve completely after one course of treatment. Patients with cardiac involvement who have high grade AV block or a first degree AV block with a PR interval greater than 0.30 seconds should be hospitalized and have cardiac monitoring. Treatment with intravenous antibiotics is recommended, and these patients may need to have temporary pacemakers.