Millions of people currently have hepatitis infections but don't know it, says the World Health Organization on the eve of the United Nations' first World Hepatitis Day.

More than 2 billion people -- or about one third of the world's population -- are infected with a form of the liver disease, which kills about a million people annually.

According to the Public Health Agency of Canada, about 600,000 Canadians live with hepatitis B and hepatitis C, two of the five strains of the virus.

Hepatitis takes a "staggering toll" on health care systems, WHO hepatitis specialist Steven Wiersma told a news conference this week, and is the main cause of liver cirrhosis and liver cancer.

And yet most of those with the infection do not know they have it, and could be unknowingly transmitting it to others.

"This is a chronic disease across the whole world, but unfortunately there is very little awareness, even among health policy-makers, of its extent," Wiersma said.

While there are actually five strains of hepatitis, hepatitis B accounts for the majority of the world's cases. It's transmitted in much the same ways as HIV is spread -- through contact with infected blood or other body fluids -- and yet it is 50 to 100 times more infectious, making it easier to catch.

About 90 per cent of healthy adults who become infected with hep B can recover and be completely rid of the virus. But the outlook for infected children is not as bright.

About 25 per cent of those infected with hep B as a child will later die, either from liver cancer or liver cirrhosis caused by the infection.

Hepatitis A, caused by a separate but related virus, is spread by the fecal-oral route, through ingesting food or drink contaminated by an infected person's stool. The disease is linked to poor sanitation and epidemics are common in many areas of the world.

Hepatitis C, spread through infected blood, can range in severity from a mild illness that lasts a few weeks to a serious, lifelong chronic condition that badly damages the liver.

Hepatitis D and E are rarer forms that are almost non-existent in the developed world, but are linked to poor sanitation in less developed areas.

The World Hepatitis Alliance, a non-governmental organization, has been marking July 28 as a day of hepatitis awareness since 2008. The WHO's governing body voted last year to join the effort with a worldwide program of ads and social media campaigns, to help raise awareness and to encourage vaccination.

Effective vaccines already exist that can prevent infection with hep A and B viruses. A vaccine for hepatitis E had been developed though is not widely available. There are no vaccines for the C and D viruses.

About 180 of the WHO's 193 member states, including Canada, now include the hepatitis B vaccine in infant immunization programs. But much more needs to be done to prevent or control the disease, even in Canada.

Dr. Mel Krajden, Co-Medical Director of Clinical Prevention Services at the B.C. Centre for Disease Control, says hep B vaccination programs have been effective at reducing the number of new infections, but help is still needed for those who already have the illness.

"For those already infected with hepatitis B, there is still a need for diagnosis and treatment, which can control infection and improve outcomes," he said in a BCCDC news release.

"Although there is no vaccine to prevent hepatitis C, new antiviral drugs will bring the hope of cure to most individuals in next few years."

The Canadian Coalition of Organizations Responding to Hepatitis B and C released its report card Wednesday on Canada's efforts to address the viruses, on the eve of World Hepatitis Day.

The report found that the provincial and territorial governments need to do a better job to co-ordinate their efforts to deal with hep B and hep C.

"There is no national strategy or comprehensive system for care, treatment and prevention of hepatitis B and C, and access to timely treatments is inadequate and inconsistent from one jurisdiction to another," the agency said in a news release.

The agency proposes that the federal government adopt a six-pronged national strategy by 2012 that includes expanded education, immunization and harm reduction programs, improved access to care and treatment, and increased recruiting and training of health professionals to deal specifically with the viruses.