February 16, 2011

Hepatitis C Cases Remain Stable: CDC

New data from the U.S. Centers for Disease Control show that new cases of hepatitis C have remained stable since dropping dramatically during the early 1990s.

During the mid-1980s, about 70 of every one million Americans developed acute hepatitis C each year, the CDC said.  However, that rate was 90 percent lower, or only 7 per million per year, between 1994 and 2006.

Intravenous drug users accounted for a growing proportion of hepatitis C cases over the years, and their risk of infection remains an important public health issue, the CDC researchers said in the journal Archives of Internal Medicine.

New hepatitis C infections are usually not obvious, and in most cases exhibit no symptoms initially.  Instead, the virus quietly damages the liver for years until it is diagnosed. 

Roughly twenty five percent of newly infected patients have what's known as "acute hepatitis," which includes symptoms such as fever, nausea and a yellowing of the skin due to improper liver function.  These patients also tend to feel particularly sick.

Tracking rates of acute hepatitis C gives researchers a sense of whether rates of silent new infections are rising or falling, the health agency said.

Hepatitis C is passed through contact with infected blood, typically by sharing contaminated needles, although a small percentage of cases are sexually transmitted or passed from mother to baby during childbirth.

Measures to curb hepatitis C transmission among drug users have so far "had success to some degree," said Dr. John Ward, director of the CDC's division of viral hepatitis who was not involved in the current study, in an interview with Reuters.

In conducting the study, Dr. Ian Williams and colleagues analyzed rates of acute hepatitis C reported in six U.S. counties between 1982 and 2006, and found that the rate of new infections had dropped.

They also found that among those receiving transfusions, for instance, the risk of infection from hepatitis C virus in the blood steadily fell over time.  Indeed, just five possible cases were identified between 1994 and 2006.

All donated blood in the U.S. has been tested for hepatitis C since 1992, and the risk of receiving a donation tainted with the virus is estimated at one in 2 million, the CDC said.

The number of cases related to injection drug use also fell over time, although drug abuse accounted for a growing percentage of acute hepatitis C infections, increasing from 32 percent of cases in the 1980s to more than 46 percent for the years 1994 through 2006.

In more than 30 percent of cases, there was no clear risk factor, although most of those people reported past drug abuse.

Efforts to limit HIV transmission among I.V. drug users have also been very effective, Dr. Ward said.

However, it has been more difficult to battle hepatitis C, because it spreads more easily than HIV, he added.

Even a tiny amount of blood on a shared needle could transmit hepatitis C, he said.

Furthermore, injection drug users' knowledge of how to prevent hepatitis C transmission "is just not as deep as it is for HIV," Dr. Ward said.

The other continuing public health concern involving hepatitis C is the large number of Americans with chronic infection who may someday develop serious liver disease.

An estimated 3.2 million Americans are living with chronic hepatitis C, about half of which are unaware of the disease, Ward said.

These people often develop inflammation of the liver, cirrhosis (scarring of the liver tissue) and in some cases, liver cancer.  

Indeed, in the U.S. and many other nations, hepatitis C is the number one reason people require liver transplants.

The CDC recommends that people at elevated risk for hepatitis C -- including those with a history of injection drug use and those who received a blood transfusion or organ transplant before 1992 -- be tested for the virus.  If an infection is discovered, doctors can conduct routine blood tests of liver function to detect early signs of liver disease.

There are also medications for hepatitis C patients that can clear the virus in some people.


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