Almost 50,000 of patients in Britain could have contracted a potentially deadly infection after undergoing open heart surgery with the use of contaminated medical equipments. At least 15 patients have apparently died from the bug, and 47,000 will be warned about possible Mycobacterium chimaera infection.

Reports also say that other nine patients are still in critical condition after contracting Mycobacterium chimaera, which can remain dormant for years and can destroy healthy blood cells in the body. Among the patients is a seven-year-old-child, whose current status is withheld from the public.

The patients known to have been infected develop deep-tissue infections. This includes abscesses on the aorta and endocarditis, which is the inflammation of the thin membranous lining endocardium of the heart’s cavities.

The problem has been made aware to the health officials since 2014. However, it is only now that they are trying to warn the thousands of Britons who may have contracted the bacteria due to the equipments used when they underwent heart valve operations.

The patients will be informed of the symptoms of the infection and would be urged to see their doctor if they remain anxious. The infection can be treated with antibiotics, however. Still, it can be deadly if an infected patient refuses to seek medical help.

Two families have decided to sue the NHS after their loved ones died from the infection. They claim that their loved ones’ deaths could have been avoided if health officials acted early. The victims got infected when healthcare workers used a contaminated machine that is used to heat and cool blood when it is circulated outside the body during surgery. The equipment should have been sterilized to avoid the problem.

Paul Balen, a clinical negligence expert from Freeths Solicitors in Nottingham, says that the reported deaths are just the tip of the iceberg of the total number of deaths caused by the infection. Balen believes that hundreds must have died from it. In a statement, NHS England and Public Health England said that contracting the infection is low. They explain that they needed to plan carefully in notifying the patients without causing undue alarm.