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HEPATITIS C
Five different viruses (termed A,B,C,D, and E) cause viral hepatitis. Three other viruses that cause hepatitis
have been identified, but not much is known about them. Hepatitis C
virus (HCV) is known to account for the great majority of what was previously
referred to as non-A, non-B hepatitis. The hepatitis C virus was identified
and described in 1989, and in 1990 a hepatitis C antibody test (anti-HCV)
became commercially available to help identify individuals exposed to HCV.
How Will I Know If I Have Hepatitis
C?
In general, individuals
infected with HCV are often identified because they are found to have
elevated liver enzymes on a routine blood test or because a hepatitis C
antibody is found to be positive at the time of blood donation. In
1992, a more specific test for anti-HCV became available and eliminated
some of the false positive reactions that were previously troublesome.
In general, elevated liver enzymes and a positive antibody test for HCV
(anti-HCV) means that an individual has chronic hepatitis C. However, the
anti-HCV may remain positive for several years after recovery from acute
hepatitis C. A small percentage of the patients still may have false positive
hepatitis C antibody reactions. In these two cases, liver enzymes are typically
normal.
It appears that the formation
of antibodies in response to the virus (associated with immunity in other
forms of viral infections) does not apply with hepatitis C. Researchers
believe this is because the virus changes to new forms of the original
virus which caused the body to produce antibodies. It is estimated that
up to 85% of the 150,000 people infected with the hepatitis C virus each
year will develop chronic hepatitis. There
are 3.5 million Americans chronically infected with HCV.
Can I Give the Disease to Others?
HCV can be transmitted
through blood transfusions. However, all blood is now tested for the
presence of this virus by the antibody test. It is estimated that the risk
of post transfusion hepatitis C has been reduced from the 8-10% frequency
of infection several years ago to less than 0.5%. Other individuals who
may come in contact with infected blood, instruments, or needles, such
as I.V. drug users, health care workers or laboratory technicians are
also at risk of acquiring hepatitis C. Currently, there is no vaccine available
to immunize individuals against this virus.
The risk for transmitting hepatitis
C sexually is unknown. There have been rare, documented cases of people
with chronic hepatitis C transmitting the virus to their only, long-term
sexual partner. The Centers For Disease Control and Prevention (CDC)
says that because of the lack of sufficient information those with only
one, long-term sexual partner need not change their sexual practices.
Many physicians who counsel patients with hepatitis C recommend the same
thing to those in a monogamous relationship.
CDC says there is an increased
risk of becoming infected with hepatitis C if you have multiple sex partners.
Whether the use of latex condoms is 100% effective in preventing someone
from infecting their sexual partner or becoming infected is uncertain.
What is the Natural History of Hepatitis
C?
Specific information
regarding the natural history of hepatitis C is not yet available. In general,
however, chronic hepatitis C appears to be a slowly progressive disease
that may gradually advance over 10-40 years. There is some evidence
that the disease may progress faster when acquired in middle age or older.
In one study, chronic hepatitis by liver biopsy was identified on the average
of ten years following blood transfusions and cirrhosis
on an average of 20 years. It also appears that HCV, like the hepatitis
B virus, is associated with an increased chance of developing hepatocellular
carcinoma, a type of primary liver cancer. Almost all HCV-related
liver
cancer occurs with cirrhosis (scarring) of the liver. The exact magnitude
of this risk is unknown but appears to be a late risk factor occurring
on the average of 30 years after the time of infection. This is more prevalent
in the Far East than in the U. S.
Is There a Treatment for Chronic
Hepatitis C?
The drug, interferon
-alpha 2b has been approved for the treatment of chronic hepatitis
C. Approximately 40% of patients treated for six months with interferon
will respond, showing major improvement or normalization of liver tests
and reduced inflammation on liver biopsy. However, of those who respond
to treatment, approximately 60% will suffer a relapse during several
months after interferon treatment is discontinued. Thus, only 10-15%
of patients treated with interferon have a sustained, long-lasting response.
Patients can be treated a second time and 85% of patients will enter a
second remission; however, the duration of treatment and dosage required
for long-term remission in this group of patients has yet to be determined.
In a recent multi-center trial in Europe, 44% of the hepatitis C patients
on the standard dosage for 18 months had their elevated liver enzymes return
to normal. This group was evaluated 19 to 42 months after this initial
18 month therapy and half of them (22%) still had normal liver enzymes.
The hope is that improvement or normalization of liver tests and reduced
inflammation in the liver will slow or interrupt the development of progressive
liver disease. However, the true impact of interferon treatment on the
long-term course of chronic hepatitis C and survival is unknown.
But in an area in Side
effects caused by interferon therapy are frequent and include "flu like"
symptoms, depression, headache, and decreased appetite. The "flu like"
symptoms can be minimized by taking two doses of acetaminophen (e.g., Tylenol).
In addition, interferon may depress the bone marrow leading to difficulties
with the white blood cells and platelets. Frequent blood tests are needed
to monitor white blood cells, platelets and liver enzymes. A liver biopsy
is typically done prior to treatment to determine the severity of liver
damage and provide confirmation of the underlying disease.
What Should I Do If I Test Positive
for the Hepatitis C Virus?
You should seek referral to a gastroenterologist
or liver specialist so that further testing can be performed to determine the
significance of the reactive antibody and whether or not you have chronic
hepatitis C.
HEPATITIS C TEST RESULTS
| TEST |
RESULTS |
INTERPRETATION |
RECOMMENDATION |
| anti-HCV |
pos. |
chronic hepatitis, chronic hepatitis C recovered,
recent acute hepatitis C, or false positive test |
further evaluation |
anti-HCV
ALT
supplemental
test (RIBA-2) |
pos.
normal
pos.
. |
possible chronic HCV carrier, may have chronic
hepatitis C |
further evaluation |
anti-HCV
ALT
supplemental
test (RIBA-2) |
pos.
elevated
pos.
. |
presume chronic hepatitis C |
further evaluation/ consider interferon therapy |
anti-HCV
ALT
supplemental
test (RIBA-2) |
pos.
normal
neg. or
indeterminate |
presume false positive anti-HCV or recovered |
further evaluation by HCV-RNA PCR test if RIBA-2
negative or indeterminate |
anti-HCV
ALT
supplemental
test (RIBA-2) |
pos.
elevated
neg.
. |
presume false positive anti-HCV, false negative
supplemental test unlikely |
further evaluation for liver disease other than
hepatitis C |
ALT
(no other
symptoms) |
elevated
.
. |
possible fatty liver, chronic viral hepatitis,
alcoholic liver disease, hemochromatosis, drug induced liver injury, other
liver diseases |
further evaluation |
Definitions:
-
Anti-HCV-antibody to hepatitis C virus.
-
ALT-Liver enzyme released from liver cells that are
injured, eg. by virus, alcohol, fat, drug, etc.
-
RIBA-2 - Supplemental test to detect antibody to
hepatitis C virus.
-
Indeterminate means 1 of 4 antigens positive.
-
HCV-RNA test by polymerase chain reaction (PCR) determines
whether the virus is multiplying.
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