Each year, an estimated 400,000 people in the United States will be diagnosed with Lyme disease, a billion-dollar healthcare problem caused by a bacterial infection that is transmitted through the bite of a tick. The condition can cause joint pain and fatigue, but is treatable with antibiotics. Left untreated, though, it can progress and cause more serious symptoms including facial palsy, an irregular heartbeat, and nerve pain. Tarsus Pharmaceuticals is developing a human formulation of the antiparasitic lotilaner, to prevent Lyme disease. We spoke to Bobby Azamian, CEO of Tarsus, about Lyme disease, the case for the company’s experimental prophylactic drug TP-05, and why you may already have been using a form of the drug to protect a four-legged member of your household.