Nobody knows how many inmates have the disease; by some estimates, around 40 percent of the 2.2 million in jail and prison are infected, compared with just 2 percent of the general population.
Eventually, when they are released, medical experts predict they will be a crushing burden on the health care system, perhaps killing as many people as AIDS in years to come. At the same time, they will be carriers, spreading the disease.
Hepatitis C can be treated, but many prisons do not test for it. Among the reasons: Budgets are tight, and treatment is expensive. So prison officials close their eyes to the gathering emergency and pass it along to the outside world.
"Right now there's a golden opportunity to bring solutions to this problem before it hits," said Dr. John Ward, director of viral hepatitis at the National Center for HIV/AIDS at the Centers for Disease Control and Prevention in Atlanta.
Hepatitis C is already the most common disease of its sort in the United States -- a chronic, life-threatening, blood-borne infection. It is most commonly linked to infected needles used for drugs, though prison tattoos and body piercing with non-sterile equipment are also risky.
What makes this virus particularly insidious is that as many as half of the people who have hepatitis C don't even know they have it. The "silent killer," already considered epidemic by the World Health Organization, often remains dormant for decades.
Some of the infected are lucky: One in five people who get hepatitis C will clear it out of their system naturally. But without treatment, one in four will suffer liver failure or develop liver cancer. Last year liver cancer was the only one of the top 10 fatal cancers in this country to increase, in large part because of hepatitis C.
More than $1 billion is already spent each year on this country on hepatitis C, and those costs are expected to soar unless prevention and treatment are expanded.
Without those changes, researchers project that liver-related deaths will triple from around 13,000 in 2000 to 39,000 by 2030. It's also estimated that 375,000 Americans with hepatitis C will develop cirrhosis by 2015.
Anita Taylor, 48, is already there, in end-stage liver disease. Taylor speaks very slowly and moves with care. She often finds that she can't say the words she wants to -- they just won't come out. Her body hurts most of the time. Her nose bleeds a lot.
A mother of two and former heroin addict, Taylor said she learned she had hepatitis C when she was jailed in Nevada in 1991 for being under the influence of drugs.
"They tested me and told me I had hepatitis C. They didn't tell me there was a treatment and a cure," she said. "And I didn't know to ask."
10 percent treated
Limited studies indicate that fewer than 10 percent of prisoners who have contracted hepatitis C are treated. The reason vary. Medical staff have other priorities, and not all are well-informed about the disease. Prisoners with short sentences are often excluded because they won't be able to complete treatment, and drug addicts who are inclined to return to risky behavior are often turned away because it is assumed they will simply reinfect themselves.
Usually, though, it comes down to money. Prison officials say that even if they wanted to provide the treatment, it is extremely expensive -- about $9,500 per patient per year -- and no federal funds have been earmarked to pay for it.
"It's a hard sell to convince taxpayers why additional resources should be spent on the health care of the incarcerated when there are a lot of people who aren't incarcerated who don't have adequate health care," said Dr. Joseph Bick, chief medical officer at the California Medical Facility at Vacaville.
Many of the inmates in Vacaville's hospice unit -- reserved for those given six months or less to live -- are dying from hepatitis C-related ailments. Bick said half of the prison's 3,200 inmates have a history of having been infected with hepatitis C, and at any given time about 40 of those men are receiving the intensive drug treatment to cure it.
The course of treatment can take a year, and involves taking pills twice a day and weekly injections. Side effects are like those associated with chemotherapy -- nausea, exhaustion, depression, debilitating aches and pains -- and the cure only works about half the time.
But Bick said the high cost of treating prisoners for hepatitis C is a bargain compared to the bill that would come due if these cases are left untreated. "It's a tremendous opportunity for us to have an impact on the larger health of the community," he said.
Dr. Lynn Taylor, an assistant professor of medicine at Brown University's medical school, agrees that prison is "perhaps one of the best settings for treatment of high-risk individuals."
"Prison can be a window of opportunity to reduce the reservoir of infection," Taylor said.