 Hepatitis is a disease that impairs liver function either temporarily
or permanently, sometimes leading to death. It can be initiated by a
host of factors but primarily by viruses. Drugs also can cause hepatitis.
However when the specific drug is discontinued, the liver usually returns
to normal. Because of the threat of grave consequences, we have to take
hepatitis seriously and do whatever is necessary to prevent its occurrence
and its damage to our bodies.
The following descriptions of various types of hepatitis will help
you understand the different types of hepatitis.
Hepatitis A virus (HAV) infection
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Referred to as epidemic hepatitis, this form is
mainly transmitted by contaminated food and water.
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Most HAV infections are asymptomatic (no symptoms)
or mild, without jaundice (yellowing of the skin).
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More than 1 million HAV cases occur worldwide,
with an estimated 152,000 cases in the United States annually. From
the time of infection, symptoms can take 15 to 40 days to appear,
but the average is 25 days.
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Usually, children younger than 5 don't have symptoms.
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The HAV death rate is less than 0.1 percent, sometimes
killing older people or those with suppressed immune systems or preexisting
liver disease.
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HAV infection does not progress to chronic hepatitis,
but a small percentage of patients have relapses of hepatitis weeks
to months after recovery from an acute (short-term) attack.
Hepatitis B virus (HBV) infection
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This type is essentially a blood-borne virus with
other bodily fluids being infectious, notably semen and saliva, and
is often transmitted from mother to fetus.
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HBV is considered an occupational hazard of medical
and dental personnel. Surgeons, oral surgeons and pathologists are
at highest risk.
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More than 200 million people are infected with
HBV worldwide. Number of new infections each year has declined from
an average of 260,000 in the 1980s to about 73,000 in 2003.
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The highest rate of disease occurs in 20- to 49-year-olds.
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Thirty percent to 40 percent of people with HBV
infection do not have symptoms and can unknowingly pass HBV to others.
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HBV is 100 times more infectious than HIV.
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The true rate of chronic infection after acute
B hepatitis is as low as 1 percent in young adults with normal immune
systems.
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The likelihood of becoming an HBsAg carrier (someone
who has a persistent infection) after acute HBV infection is especially
high among those with Down syndrome, immunosuppressed patients, including
those with HIV infection, or patients on long-term hemodialysis.
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About 30 percent of HBV cases are related to sexual
activity, either unprotected sex with an infected person or multiple
sex partners.
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HBV can live on a dry surface for at least seven
days and can take up to 160 days between the time of infection and
the onset of symptoms. The onset of symptoms averages 10 weeks.
Hepatitis C virus (HCV) infection
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Before a blood test was discovered in 1989 to
screen for HCV, this was the most frequent hepatitis to be acquired
from blood transfusions and blood products.
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HCV is one of the leading infections causing chronic
hepatitis. Seventy percent to 80 percent of people who have acute
HCV develop chronic infection. A small portion of those with chronic
disease will go on to develop liver failure and need a transplant.
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An estimated 3 million Americans, nearly 2 percent
of the population, are chronically infected with the hepatitis C virus.
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HCV is a more frequent cause of chronic liver
disease than hepatitis B.
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Almost half of liver transplants are done for
patients with hepatitis C.
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Each year, 8,000 to 10,000 people die in the United
States because of hepatitis C-related cirrhosis or HCV-related liver
cancer.
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The risk of HCV infection is increased in organ
transplant recipients and in AIDS patients.
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Chronic hepatitis C occurs in as many as 20 percent
of renal transplant recipients.
Hepatitis D virus infection
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Hepatitis D virus infection only occurs in the
presence of hepatitis B infection.
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HDV infection is transmitted by blood and blood
products.
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Co-infection with HDV can be acquired at the same
time a person is infected with HBV.
Hepatitis E virus infection
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HEV is transmitted through water or food.
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HEV occurs in tropical and subtropical countries.
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HEV also can be spread from person to person.
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HEV affects young adults, rather than children,
and causes a high mortality rate, particularly in pregnant women.
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In industrialized countries this disease occurs
occasionally as imported sporadic cases.
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HEV epidemics are most often associated with contaminated
drinking water.
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