- overlooked epidemic, Part II
3/19/2001 Find out why no vaccine has yet
addressed this silent
epidemic--one thats far more likely to be
occupational needlestick injury than HIV. For Part
I, click here.
By Lisa Black, RN, BSN
Often called the silent epidemic, Hepatitis C
is transmitted primarily by blood-to-blood
contact with an infected source. The World
Health Organization estimates that more than
170 million people worldwide are infected,
including 4 million people in the United
States, although many of the infected remain
While the majority of new Hepatitis C virus
(HCV) transmissions are a result of illicit drug
infected healthcare workers represent an
ever-growing subset of the
HCV infected population. Given that an
healthcare worker runs a 2% to 10% risk of
seroconversion after a
single HCV exposure, HCV is greater than 100 times
more likely to
be transmitted by an occupational needlestick
injury than HIV.
Hepatitis C has earned its alias as the silent
epidemic because, in a
great number of people, the disease remains
silent for years or
decades, and only becomes evident when the virus
irreparable liver damage. In fact, only 10% of
patients infected with
HCV report an acute hepatic illness when they
acquire the infection.
Notwithstanding the initially asymptomatic nature
of the majority of
infections, over 85% of those infected will become
chronic carriers of
the virus and many of those will eventually
develop liver disease, often
necessitating liver transplantation or leading to
The Hepatitis C virus has, thus far, proved
elusive to researchers, and
unlike hepatitis A and B, there is no vaccine to
prevent hepatitis C
infection. The explanation for this failure lies
within the structure of the
Hepatitis C virus.
The hepatitis C virus is an RNA virus that
replicates via a virally
encoded RNA polymerase. The replication cycle of
generates large numbers of mutant viruses
differing from the parent
strain by possibly only a few nucleotides. Each
however, changes the viruss structure, which
renders any previously
developed vaccine ineffective. The mutation rate
with hepatitis C is
such that various quasi-species may exist
any given carrier, further complicating efforts to
treat the disease.
Although every hepatitis C virus is unique and
careful comparison of viral sequences has allowed
HCV to be grouped
into closely related groups known as genotypes.
genotype, the virus is similar to the groups
other members but differs
greatly from those in other genotype groups.
The various HCV genotypes tend to be endemic to
geographic locations. In the United States,
genotypes 1, 2 and 3
predominate, with genotype 1 being the most
unfortunately, the most difficult to treat.
While differing HCV genotypes dont appear to have
a direct effect on
the natural history of the disease, there is a
significant difference in
response to treatment among genotype groups.
studies are boasting an 88% rate of cure in
patients infected with
genotypes 2 and 3 (as expressed by a sustained
virus clearance six
months after treatment). But the same treatment
yields only a 48%
efficacy in those carrying genotype 1 HCV
In the next article in this series, Ill review
the history and evolution of
HCV treatment, and discuss some of the promising
options on the horizon.
Send questions or comments to Lisa at
also visit her website dedicated to needlestick
Click here for more Sharps Safety.
The Gastroenterology Treatment Reporter,
Outcomes: Customizing Treatment for Patients with
January 23, 2001.