Tick Bite Workup: Geography Drives the Differential, and Timing Determines the Test
Tick Bite Workup: Geography Drives the Differential, and Timing Determines the Test Don’t order Lyme titers the day after a tick bite. They’ll be negative. And don’t order them at all if the patient was bitten in Oklahoma. Tick-borne illness is one of primary care's most geography-dependent diagnoses. The tick species, the pathogen it carries, the region where the bite occurred, and the timing of your lab work all determine whether you'll catch the diagnosis or miss it entirely. This post maps out which diseases to suspect based on location, when to test, what tests to order, and—critically—when to treat empirically before labs come back. Step One: Identify the Tick and the Geography Tick Species Common Name Primary Geography Diseases Transmitted Ixodes scapularis Blacklegged tick / Deer tick Northeast, upper Midwest, mid-Atlantic (CT, MA, NY, NJ, PA, MN, WI) Lyme disease, Anaplasmosis, Babesiosis, Powassan virus, B. miyamotoi relapsing fever Ixodes pacificus Western blackleg...