Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.
Hepatitis is a general term that means inflammation
(irritation and swelling) of the liver. Inflammation of the liver can result
from infection, exposure to alcohol, certain medications, chemicals, poisons, or from a disorder of the immune system.
Hepatitis A refers to
liver inflammation caused by infection with the hepatitis A virus (HAV). HAV is
one of several viruses that can cause hepatitis, and is one of the three most
common hepatitis viruses in the United States. The other two common types are
hepatitis B and hepatitis C; however, there are other named types such as D, E,
F, and G, and more types may be discovered in the future. Moreover, these infections are
somewhat different from hepatitis A, and from each other.
Unlike hepatitis B
and hepatitis C, hepatitis A does not cause chronic (ongoing, long-term)
disease. Although the liver becomes inflamed and swollen, it heals
completely in most people without any long-term damage. Once a person contracts
hepatitis A, they develop lifelong immunity, and rarely contract the disease
again.
Because of the way it is spread, the hepatitis A virus tends to occur
in epidemics and outbreaks. As many as 1 in 3 adults (>age 19) in the United States have
antibody to HAV , meaning they have been exposed to the virus, but most do not
become ill. In 2011, researchers report no significant change in seroprevalence
(the frequency of people in a population that have particular antibodies,
usually reactive against a disease-producing organism in their
blood serum) of HAV antibodies in adults before or after the HAV vaccine became
available (see reference 3). The number of cases of hepatitis A in the United States varies among
different communities, and has been reduced by the
introduction of the hepatitis A vaccine.
The rate of infection (number of infections per 100,000 people) has declined
since 1999 from 6.3 to 0.9 per 100,000 people (2008 CDC statistics). About 2,500
to 3,600 cases
of hepatitis A are reported each year in the U. S., but many more people
may be exposed to the virus, but have few, if any,
report symptoms. Vaccination at age one year may cause the rate and yearly case
numbers of HAV to decline.
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What is the hepatitis A vaccine, and who
should get one?
There are vaccines that work to prevent infection with hepatitis A virus.
The vaccines, Havrix and VAQTA, contain no live virus and are very safe. No
serious adverse effects have been reported. Some people have some soreness at
the injection site for a few days.
The vaccines are given in a series of 2 shots. The second is given 6-18
months after the first. The shots can be given at the same time as other
vaccines.
Your protection starts about 2-4 weeks after the first shot. The second
dose is necessary to ensure long-term protection.
The vaccines are thought to protect from infection for at least 20 years.
The vaccines must be given before exposure to the virus. They do not work
after exposure.
Not everyone needs to have the hepatitis A vaccines. However, the vaccines
are recommended for the following groups:
People who are likely to be exposed to HAV at work - The only group of
workers shown to be at higher risk than the general population is people who
work in research laboratories where HAV is stored and handled. Routine
vaccination is not recommended for health care workers, food service workers, daycare personnel, and sewage and waste-water workers.
Individuals visiting developing countries (it must be given at least 4 weeks before
the trip)
Men who have sex with men
People who use illegal drugs - This group has higher-than-average rates of
HAV infection.
People who are likely to become seriously ill if they are infected with HAV
- This includes people with impaired immune systems or chronic liver disease.
People with blood-clotting disorders who receive clotting factors
