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JEFFERSON CITY - A recent congressional report revealed that millions of Americans could be infected with the hepatitis C virus and not know it.
Because the infection is very mild, often taking years to develop into serious liver disease or damage, most people aren't aware of the liver-destroying virus until it is too late.
"It is easy to brush off and it is easy to ignore. Compared with most other infections, the levels of the virus are extremely low," said Dr. Paul King, a liver specialist at University Hospital and Clinics. "Damage is done over 10 to 20 years, so they (patients) don't feel bad, yet over those long periods of time, it can cause progressive damage."
King said those at risk of developing chronic hepatitis C are IV drug users and people who have given or received blood prior to 1990, when a screening test was developed. Other ways the virus can be spread is by using shared needles, unsanitary tattoo and body piercing parlors and through a kidney dialysis treatment.
A simple blood screening test, which can be done by a family doctor, is an important safeguard that is often overlooked by doctors.
What makes the disease so problematic, King said, is that people don't feel sick, unlike hepatitis A. With that variation of the virus, a person gets very sick and then gets over it, relatively quickly.
But a hepatitis C infection lingers around, sometimes for up to 20 years, before manifesting itself. That makes early detection difficult for doctors.
Dr. Bruce Bacon, a liver specialist at St. Louis University, estimated that about 80,000 Missourians are now infected with hepatitis C. It is virtually impossible to get an exact number because most people haven't been tested for the virus.
"Prior to 1990, seven to 10 percent became infected with hepatitis C," he said. "Now it is down to 1 percent thanks to testing."
Still, testing only prevents new people from getting infected. King estimates he sees about 200 new cases each year at his Columbia office.
Hepatitis C infects an estimated 170,000 new cases every year, according to the Center for Disease Control. Nationwide, the center puts the number of Americans infected with the virus at 3.9 million people.
By comparison, there are about 1 million Americans with HIV, the virus that causes AIDS, the CDC estimates.
To add to the problem, not everyone exposed to the virus will develop symptoms. Of those exposed to hepatitis C, 90 percent come down with chronic hepatitis. Then up to half of those people will develop cirrhosis -- the destruction of the liver.
Once detected, King said, anti-viral agents such as drug Interferon are used to combat the disease. Everyone who is found to have the virus is given the drug because doctors aren't able to predict which patient will develop symptoms.
The virus' life cycle accounts largely for how the virus behaves. Similar to HIV, hepatitis C is a RNA virus, that infiltrates a host cell. Where HIV destroys the body's immune system, hepatitis goes to work on the liver.
Hepatitis C first must splice itself into the liver cell's DNA by undergoing a process called reverse transcription. Once it becomes part of the host DNA, it will begin to replicate after some time.
Here, King said, is where part of the problem lies.
"There is a lot of errors in replication, so there is always mutants that arise," he said. "You can develop an immunity to one mutant but not to the others.
"The trend over a long period of time is often progressive fibrosis," King said.
King and Bacon are researching new methods to fight the virus. King said he is doing clinical studies on the effectiveness of Interferon with other anti-viral agents.
The study is only a year old so King wouldn't speculate on the effectiveness of the trials but did say that more is being done to understand the virus and how it works.