department says a team of disease detectives immediately began to actively trace all of the patient's contacts to identify anyone who may be at potential risk. >> the patient is now in isolation. the health department has a team of disease detectives who have been at work tracing all of the patient's contacts and we are prepared to quarantine contacts as necessary. >> reporter: in recent days, bellevue hospital has been holding drills in case a possible ebola patient comes through their door. those plans going into motion. >> reporter: it took only a few hours to determine that spencer did, indeed, test positive for ebola. linsey davis, abc news, new york. >> this is what we know about dr. spencer's past few days. he left guinea october 14th, stopped in brussels before arriving in new york on the 17th. he sticks to guidelines checking his temperature twice a day. this past tuesday he feels tired. wednesday, spencer takes the subway to brooklyn to a bowling alley and hops in a cab back home. he notifies authorities