Better services are needed for an estimated 25,000 people who have Hepatitis C but do not know they have the potentially fatal disease, medical specialists say.
It is estimated about 50,000 New Zealanders are living with the disease which can lead to cirrhosis of the liver and liver cancer if not treated.
The problem in Australia is causing alarm, with those who contracted Hepatitis C decades ago only now starting to develop terminal liver disease after the virus has laid dormant for decades.
Cases of Hepatitis C are expected to continue to grow in the western world, with many baby boomers who experimented with drugs in the 1960s and 70s only now learning they have the disease.
Auckland City Hospital liver specialist Edward Gane, who is recognised as a world expert in his field, said Hepatitis C affected all ethnic groups in New Zealand.
"It's important for the general public to know that anyone at risk for Hepatitis C in the distant past, such as any recreational drug use, any tattoos outside licensed parlours, any blood transfusions prior to 1992, go and get tested."
People returning to New Zealand after living in a high-risk country such as South East Asia, China, Eastern Europe or the Middle East should be tested.
Professor Gane said worldwide the number of people with the disease is rising.
Drug Foundation chief executive Ross Bell said there were about 1000 new infections a year and more government support was needed.
General practitioners needed to do more screening of those people most at risk, he said.
"We need to do more to reach those people through the important channels of needle exchange programmes and through people's primary care provider.
"We've seen earlier efforts in trying to reach this population. We don't think those efforts have actually gone through the right channels and so we would like to see greater outreach, greater Hepatitis C education awareness and quick testing through the needle exchange programme."
Kaitaia doctor Lance O'Sullivan said it was great that Dr Gane was highlighting the issue of undiagnosed hepatitis infection in New Zealand.
He screened all his Māori patients for Hepatitis B but, like many doctors, was probably not doing enough testing of Hepatitis C, he said.
Despite the other demands placed on doctors to do screening of illnesses such as diabetes there was a responsibility to react to the problem, Dr O'Sullivan said.
"We should be able to respond to our patients' needs. At the end of the day we should be able to respond to our community... depending on the particular makeup and demographics of the community.
Auckland University's immunisation advisory centre director and general practitioner, Dr Nikki Turner, said all doctors needed to do systematic screening and try to follow up with high risk people, and there was always more that they could do.
Other services should try to screen patients suspected of having Hepatitis C as well, Dr Turner said.
"Sometimes we have people that don't attend general practice regularly and turn up at emergency departments and after hours. These are places that also need to consider systematically looking for these issues.
"Usually after hours and ED are dealing with the condition that the patient turns up with, but they're not looking at broader health issues... but if you have people that aren't well-networked in with the regular general practice, other sources like those are the places they'll turn up."