TORONTO -- When Walter Buchanan learned his brother-in-law needed a liver transplant because of advanced cirrhosis caused by a long-undiagnosed infection with hepatitis C, he offered to donate part of his organ to save his life.

But Buchanan was shocked when doctors told him he couldn't be a donor -- tests revealed that he, too, carried the virus and that his liver was severely scarred, even though he'd experienced no symptoms.

"When they told me, my mind just went deep-six," he says from his home in Queensville, Ont, just north of Toronto. "And my first question was: 'OK, how long do I have?'

"That's what scares people the most about hep C, because people think 'Oh my God, it's a death sentence."'

Hepatitis C can indeed kill. Over time, the virus causes cirrhosis, which can lead to liver failure. About 10 per cent of those with advanced cirrhosis go on to develop liver cancer.

But damage from hepatitis C can take decades to manifest and cause noticeable symptoms; many people have no idea they harbour the virus -- hence its moniker as a "silent killer."

At 67, Buchanan is part of the baby boomer generation, the group that makes up roughly a quarter of Canada's population. Liver specialists contend people born between 1945 and 1965 are at the greatest risk of having been unknowingly infected by the blood-borne virus, which wasn't even identified until 1989.

Yet recently released hepatitis C screening guidelines from the Canadian Task Force on Preventive Health Care (CTFPHC) recommend against routine testing of baby boomers -- or adults of any age -- unless an individual has one or more risk factors, including a history of IV drug use; travel to or immigration from hepatitis C-endemic countries; or a blood transfusion or organ transplant before 1992, when donations weren't tested for the virus.

That recommendation has dismayed many hepatologists (liver doctors), infectious disease physicians and researchers who have long preached that all boomers should be tested for the virus, in part because they grew up at a time when doctors and dentists gave vaccinations and freezing with reusable and often inadequately sterilized needles.

Experimentation with injection drugs and potentially unsafe sex among this age group during their teenaged and young adult lives could also have ratcheted up the spread of the virus.

An estimated 250,000 to 300,000 Canadians are infected with hepatitis C, and studies suggest 45 to 70 per cent -- about two-thirds of them baby boomers -- have no idea they carry the virus.

"Hepatitis C is like having a ticking time bomb in your liver," says Michael Houghton, a researcher at the University of Alberta who first identified hepatitis C with co-investigators while working in the U.S. and then developed a blood test for the virus.

However, a new generation of antiviral drugs can wipe out the infection in more than 95 per cent of cases -- providing hope that treatment could fulfil the World Health Organization's goal of eliminating the disease by 2030. Globally, 130 million to 150 million people have chronic hepatitis C infection and up to 500,000 die each year from the disease.

"HIV we cannot cure. Hepatitis B we cannot cure. Human papillomavirus we cannot cure," says Houghton, who is working on a preventive vaccine. "With hep C, it's the first example of a human persistent virus that we can not just ameliorate but we can actually eradicate.

"So we've got this fantastic opportunity. And are we taking advantage of it? No, we're just dragging our heels," he says.

The CTFPHC working group that developed the guidelines says two systematic reviews of the medical literature found no evidence of benefit from widespread population screening for hepatitis C among low-risk adults, which they maintain covers most baby boomers.

"To our knowledge there's no good studies published at this time to show that baby boomers in Canada have an especially high prevalence of the virus," says Dr. Roland Grad of McGill University in Montreal, who chaired the 12-member working group comprised mostly of family doctors.

A key reason for promoting only risk-based testing is cost: the newer antiviral medications initially carried price tags of $45,000 to $100,000 for a treatment course of many weeks. The guideline authors estimate that widespread testing and treatment would set the health-care system back by about $1.5 billion.

"Are we going to suggest that $1.5 billion of publicly funded taxpayer money should be spent on this issue (when we) found no direct scientific evidence to support it?" says Grad.

"We were concerned that if we recommended for it in the absence of direct evidence, it could be causing more harm than good because we simply don't know if screening is beneficial," he says, explaining the high cost of the drugs could mean many people diagnosed with the virus would not be able to afford treatment.

Toronto hepatologist Dr. Jordan Feld says recent negotiations between the drug makers and the Pan-Canadian Pharmaceutical Alliance (PCPA) -- representing the federal, provincial and territorial governments -- have substantially reduced the cost of several of the hep C medications under publicly funded drug plans.

While results of those negotiations are confidential, it's believed their price tags could now be as low as $10,000 to $20,000 per patient.

Currently, patients with a certain level of liver damage or who fit other criteria, such a co-infection with HIV or hepatitis B, have their medications covered by some provincial drug plans. But in February, both B.C. and Ontario announced they will expand coverage next year to all infected residents, regardless of disease severity.

Grad says whatever deal the PCPA struck with the drug makers wasn't in place last fall when the guidelines were finalized.

"If we had clear data as to how much the costs of the drugs were going to be ... if we had a very clear sense of what was going on, we would be able to look at this again and reconsider the screening decision."

Critics say that while task force members focused on potential harms associated with the cost of treatment, they didn't consider the costs of leaving carriers unidentified and untreated.

Feld, director of research at the University Health Network's liver clinic, says even without access to treatment, those who find out they're infected can avoid transmitting the virus to others and make liver-protecting lifestyle changes such as avoiding alcohol and losing weight.

That was the case for Marsha Lecour, who was diagnosed with hepatitis C in the mid-1980s after tests showed her liver was abnormal.

"I've been vegetarian since 1972, so that stood me in good stead," says Lecour, a retired Toronto teacher who turns 65 in June. "So being vegetarian and not drinking alcohol were two factors that really were in my favour."

Still, she did develop advanced cirrhosis over the next 10 years and was treated more than once with drug combinations that included interferon, a protocol since replaced by the newer antivirals. After completing a 48-week triple-drug therapy, she was declared virus-free and her liver has since recovered significantly.

"I think all baby boomers should be tested, regardless of risk factors, because you just don't know," says Lecour, whose only known risk factor was a blood transfusion during heart surgery at age four.

"For this age cohort, the longer we wait and if we have hep C, the more damage develops over time and the harder it is possibly to treat."

Hepatitis C-induced cirrhosis can lead to liver failure, which causes the abdomen to fill with fluid and requires frequent hospitalizations, as well as jaundice, extreme fatigue and emaciating weight loss.

The only cure is a liver transplant, which costs about $250,000 if a donor organ can be found, says Toronto hepatologist Dr. Morris Sherman, chairman of the Canadian Liver Foundation.

The foundation recommends testing of all Canadians born between 1945 and 1975 -- 10 years beyond the boomer generation -- based on Public Health Agency of Canada data showing they have the highest rate of diagnosed infection.

Rates of advanced liver disease caused by the virus are on the upswing, says Sherman, noting that at the UHN clinic where he practises, the proportion of patients with liver cancer has risen from 25 per cent to 45 per cent in the last 10 years.

"If you find hepatitis C, you have an obligation to treat," he says. "The question is if you don't know about it, do you have an obligation to screen in order to find the cases to treat?

"I think we do. You have a curable disease, which if left untreated has a high likelihood of causing your death."

Buchanan, who was cured by the antivirals, says scans show his liver is now healthier and he "feels great."

His brother-in-law was not so fortunate -- he died before he could get a transplant.

If there's any silver lining, it's that Buchanan found out he had hepatitis C, though he's not sure how he got infected. Never an IV drug user, the American expat may have been exposed while serving in the Vietnam War.

As to the recommendation against screening those of his generation, he calls it "an extremely stupid approach."

"They've done so much research and they're able to cure it. It's not a death sentence anymore."