The Department of Health and Human Services confirmed it sent letters this week to patients who came into direct contact with the unnamed worker in the past three years.

The worker told the department of his diagnosis in late August and discontinued practice days later, Fairfax Media understands. An investigation into how long the worker knew of his condition is underway.

Victoria's acting chief health officer Dr Roscoe Taylor said there was a less than one per cent chance anyone had caught the virus but the department had done a thorough investigation and was taking a cautious approach by recommending tests.

"This health worker has been carrying out clinical procedures, some of which included exposure-prone procedures," he said. "These procedures have an increased risk of skin puncture and therefore potential for the transmission of a blood-borne virus."

More than 150 people have already responded to the letter and there have been no reports so far of any patient contracting hepatitis B from the worker.

"The welfare of the patients of this health care worker is our primary concern. Only patients who have been contacted directly by the department need to take any action."

He said the event it highlighted the importance of the hepatitis B vaccine.

A team of specialist public health staff is advising the patients, arranging for blood samples to be taken and the results made available to each person quickly, Dr Taylor said..

The Department would not name the hospital involved.

A spokesman said it could not legally disclose the identity of the health care worker involved or give any details about which medical procedure led to any potential exposure for patients.

Hepatitis B is commonly spread through unsafe sex with an infected person, and less frequently, through blood-to-blood incidents such as needle stick injuries.

Symptoms of the virus include abdominal pain, dark urine, fever, joint pain, loss of appetite, nausea and vomiting, weakness and fatigue, and yellowing of your skin and the whites of the eyes (jaundice).

However, many people with acute hepatitis B have no symptoms and never realise they had the infection, according to Hepatitis Australia.

Unlike the long-lingering hepatitis C, most people recover from the hepatitis B virus within six months, A very small percentage of people with acute hepatitis B become very sick in a short period of time if there is massive damage to the liver and it stops working.

The spokesman for the department of health said the worker's employer had notified the Australian Health Practitioner Regulation Agency of the issue. He said health care workers conducting exposure-prone procedures have a professional and ethical responsibility to know their own blood-borne virus status, and manage any risks accordingly.

"As part of an annual re-registration process for health care workers, AHPRA requires that they indicate if they have any condition or impairment which
may prevent them from treating patients in a safe manner," the spokesman said.

"At present in Australia it is recommended but not currently mandatory for health care workers doing exposure prone procedures to be tested for
evidence of Blood-borne viruses (including Hepatitis B)."

Two years ago, almost 400 patients were exposed to HIV through a Gippsland dentist and patients were tracked down for testing.

People wanting information or support in relation to viral hepatitis can contact Hepatitis Victoria's Infoline on 1800 703 003.

Do you know more? Email scoop@thage.com.au