More than 2,000 patients who underwent open heart surgery at London Health Sciences Centre are being warned they could be at risk of infection from an unusual bacteria.

The hospital has sent letters to everyone who received the heart surgery since January 2015 advising them they could be at risk of Mycobacterium chimaera bacteria infection.

The infection has been linked to the units that heat and cool blood during the surgery.

“It is an unusual infection. It is a very slow-growing bacteria with a long incubation period. Sometimes the infections are presented years after the surgery,” said Michael John, director of infection prevention and control at LHSC.

Though the infection can be complicated to treat, John emphasized the risk to patients is low. Officially it is pegged at one per cent, but the actual risk is probably significantly less than that, he said.

“There has been about 60 cases in North America that have been identified and obviously there have been hundreds of thousands of surgeries performed in that time period,” he said.

There haven’t been any cases identified with LHSC.

Patients are being asked to monitor for the following symptoms: night sweats; muscle aches; weight loss; fatigue; unexplained fever; and redness, heat, or pus around the sternal surgical incision.

Patients with any of the symptoms or who have been diagnosed with sarcoidosis since their heart surgery are advised to contact their family physician. Patients also can contact the hospital at 1-844-358-1050 on weekdays between 9 a.m. and 5 p.m.

John said infections originally were traced back to contamination at the manufacturer’s plant in Germany. The units used at the London hospital were ordered after the plant had been disinfected.

Studies indicate infections resulted when bacteria in the water cooling system was spread in the operating room by the fan in the unit. In London, the units were located at the side of the operating room with the fans blowing away from the patient, John said.

“It is one thing we feel encouraged about,” he said.

jminer@postmedia.com