Boston health officials said Monday that security measures have been tightened aboard the city’s ­ambulances following the discovery of drug tampering, allegedly by a Boston Emergency Medical Services paramedic.

The tampering with vials of pain medications and sedatives, discovered Sept. 6, 2011, may have ­exposed as many as 64 patients to blood-borne infections when they were treated during summer 2011, officials said.

Boston EMS chief James Hooley said that since the alleged incident, the agency has started a “very strict” inspection schedule of the ambulance medications and has ­improved packaging of the drugs.

“We feel pretty confident we have put additional safeguards in place to prevent something like this from happening again,” Hooley said.


He said that EMS already had “robust” security, which required double signatures on the painkillers and other controlled medications used and periodic inspections by super­visors, as well as an annual ­inspection by state officials.

The Boston Public Health Commission, which runs the city’s ­ambulance service, began notifying patients over the weekend and offer­ing free medical tests to determine whether they were exposed to infectious diseases.

“We have had, for the most part, a very positive response,” Barbara Ferrer, executive director of the commission, said during a press conference at the agency’s Boston headquarters. “People have been glad that we did in fact notify them, and I think it’s mixed in terms of what people are worried about or whether or not people want to get tested.”

Officials do not believe that the paramedic carried any infec­tious diseases, but they ­acknowledged that they do not know for sure. Nor do they know how the individual may have tampered with the medications, which are in liquid form and are injected.

Letters and phone calls have gone out to 57 of the 64 who may have been affected. Seven died shortly after they were taken to the hospital; officials ­believe that their deaths were not related to the suspected medication tampering and were due instead to their injury or medical event.


“The paramedic in question did not treat all 57 patients personally, and we also have no reason to believe that this individual had or was transmitting an infectious disease to any ­patients,” Ferrer said.

Dr. Anita Barry, director of the commission’s Infectious Disease Bureau, said the chances of any of the 57 being infected are quite small. She said that if the patients want to be tested for potential infections, she suggests that they be screened for blood-borne illnesses such as HIV and hepatitis C.

Someone who is directly stuck with a needle from someone who has HIV has a 0.3 percentchance of getting infected, Barry said.

“We are miles away from that here,” she added. “This has got to be much much, much lower risk.”

Similarly, Barry said, someone who is directly stuck with a needle from a person who has hepatitis C, has a 1 to 2 percent risk of getting infected.

Barry said it is possible that someone who was infected last summer may still not show symptoms, but blood tests would reveal if the person had been exposed.

The paramedic, whom officials declined to identify, is ­believed to have tampered with fentanyl and morphine, which are powerful painkillers, and sedatives lorazepam and midazolam during a six-week period in the summer of 2011, but officials said they could not be more specific about the exact dates because of an ongoing criminal investigation. No charges have been filed against the paramedic, who was ­relieved of duties when the problem was discovered in September 2011.


Ferrer said Boston EMS was unable to accurately identify the small number of patients who may have been exposed to compromised medications ­until the state drug analysis lab completed its testing of medication vials, about 200 samples, at the end of July, 10 months after the problem was discovered. She said the test results then ­allowed EMS to identify 64 ­patients of nearly 17,000 ­encountered by EMS during the time period in question who ­potentially received compromised medications.

“This is a complicated case that involved testing many samples and interviewing many people,” commision spokesman Nick Martin said when asked why patients were not informed sooner. “Until the lab results were finalized, there was no way to confirm tampering or [to] identify patients that were potentially impacted.”

Kay Lazar can be reached at klazar@globe.com. Follow her on Twitter @GlobeKayLazar.