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Hepatitis A is one of five known viruses that cause inflammation of
the liver (the others are B, C, D and E). The Centers For Disease Control
and Prevention estimate that 150,000 people in the U.S. are infected
each year by hepatitis A, a low rate compared to the rate in underdeveloped
countries. The vast majority of people recover from the infection within
six months without any serious health problems. Transmission
is usually by drinking water or eating food that has been contaminated
with fecal matter containing the virus. Unlike the hepatitis B and C
viruses, the hepatitis A virus remains stable when liver cells secrete
it into bile, which then enters the digestive tract. Fecal matter from
an infected person has a high concentration of the virus during a certain
period of infection, whereas saliva and other bodily fluids have a low
concentration. The virus can survive in this contaminated fecal matter
on a persons hand, for example, or on a surface for three to four hours
at normal room temperatures. Thus, an eating utensil contaminated with
the virus could be a way to transmit the infection to a person. Contaminated
shellfish are a frequent source of infection. Direct contact with an
infected person is another confirmed transmission route, as are kissing
on the mouth and anal sex. Contamination of needles used for intravenous
administration of drugs is a suspected route of transmission. In over
40 percent of the reported cases it is not known how these people were
infected. The
risk of being infected with the hepatitis A virus generally depends
on the hygienic and sanitary conditions in an area. High risk geographic
areas are the Middle East, South America, Eastern Europe, Central America,
Africa and Southeast Asia. There are also areas in the United States
where poor sanitary conditions or hygiene have resulted in outbreaks
of hepatitis A. It is also after symptoms appear or two to three weeks
before the appearance of the symptoms, patients will shed the virus
in high concentration in feces and thus they are most infectious to
others. The Centers for Disease Control and Prevention (CDC) lists household
or sexual contact, daycare attendance or employment and recent international
travel as the major known risk factors for the transmission of hepatitis
A. The CDC estimates that a third of the U.S. population has been infected.
Children at daycare centers spread the virus because of fecal-oral contamination
through diaper changing. Outbreaks have been reported in the military,
at institutions for the disabled and because of infected restaurant
workers. Those using injectable drugs with contaminated needles have
also been infected with the virus. As
with the other hepatitis viruses a person infected with hepatitis A
may not have any symptoms. However, in those who do have symptoms, they
resemble the flu. These symptoms include fatigue, nausea, vomiting,
pain in the liver area, dark urine or light colored stools and fever.
Liver function tests are elevated, with many adults developing jaundice.
Children under two rarely have symptoms. Most people recover within
six months. A
very small percentage of people infected with hepatitis A risk serious
complications. These include people with alcoholic hepatitis, chronic
hepatitis with cirrhosis or the elderly over 60 years old. These patients
may suffer liver failure after becoming infected with hepatitis A. Federal
mortality statistics for 1992 lists hepatitis A as the primary cause
of death for 82 people. In 1993 an estimated 121 people were hospitalized
for hepatitis A. Patients with hepatitis A may show improvement in their
symptoms and liver function tests only to suffer a relapse, usually
after four weeks. A relapse can occur more than once and there is no
way to predict who will suffer a recurrence of acute symptoms. In rare
cases, jaundice lasts for two or more months. It is rare for pregnant
women who are infected with hepatitis A to suffer serious complications
to themselves or their newborn children. Hepatitis
A is diagnosed by a blood test that is positive for the antibody to
the virus, which appears about four weeks after the infection. There
are no false positives or negatives with this test. Liver function tests
(serum alanine aminotransferase [ALT] and asparate aminotransferase
[AST]) are elevated above normal, often to very high levels. Symptoms
will normally appear during the first four weeks of infection. The
current vaccine for hepatitis A in the U.S. is manufactured by SmithKline
Beecham, Inc. The vaccine is made from an inactive hepatitis A virus
that has been suspended in a sterile solution. It is not made from infected
blood. The body reacts with the inactive virus to produce an antibody
that protects against infection of the liver by the hepatitis A virus.
Clinical trials have shown that the vaccine is effective in preventing
infection in over 90 percent of people who were exposed. There are generally
no known side effects, except for soreness at the site of the injection.
Less than 10 percent of those vaccinated become tired and nauseous.
Children between one and 18 should receive two initial doses of the
vaccine and a booster between six and 12 months. Adults should receive
an initial dose and then a booster six to 12 months later. It takes
at least two weeks before protection is achieved. It is not certain
how long protection will last. 
The American Liver Foundation is the only national voluntary health organization dedicated to preventing, treating, and curing hepatitis and all other liver and gallbladder diseases through research and education.
Copyright
© 1995 |
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