More than 22,000 patients of a dentist in Nottingham face tests to see if they caught the deadly disease from him.
The recall of patients could be the largest in UK medical history and includes patients treated by the man over three decades.
Reports say around 160 patients of the man are considered to be at "serious risk" of having caught the blood borne virus.
For the remaining thousands, the risk of infection is "low," a source told the Mirror.
"The advice has been to screen everyone. The public must be aware of the need to take action," they said.
Patients are set to be tested for other potential illnesses: Hepatitis B and C.
It is understood that the concerns came to light after the dentist in question was secretly filmed breaking rules for infection control at work.
The experienced practitioner was suspended in June for 18 months.
The NHS is currently seeking to contact all his patients, with a public appeal due today (Wednesday). A dedicated phone line is being set up for affected residents in the Midlands city to contact for information.