Thousands of National Health Service (NHS) dental patients in the United Kingdom may have been exposed to HIV, hepatitis and other blood-borne illnesses after a dentist failed to properly sterilize his equipment, The Daily Mirror reports.

According to the article, NHS is notifying about 5,700 people who might be at risk, offering them blood tests for HIV and hepatitis B and C.

In a warning letter to these patients, Chris Payne, MD, director of South Gloucestershire Primary Care Trust, recommended they get tested. He also assured them that the risk of infection from the unnamed dentist’s equipment is relatively low. Transmission, he wrote, “can only happen in the rare event that a small amount of infected blood from one person gets into the bloodstream of another patient, and the risk of this happening in dental care is very low indeed.”