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This Acute infection Profile includes EBV IgM Antibodies, Early Antigen
Antibodies IgG, Viral Capsid Antibodies IgG, Nuclear Antigen Antibodies
IgG.
Epstein-Barr
virus (EBV) antibodies are a group of tests that are ordered to help
diagnose a current, recent, or past EBV infection. EBV is a member of
the herpes virus family. Passed through the saliva, the
virus causes an
infection that is very common. According to the National Center for
Infectious Diseases (NCID), as many as 95% of people in the United
States will have been infected by EBV by the time they are 40 years old.
After exposure to the virus, there is an incubation period of several
weeks. EBV then causes an acute infection, followed by resolution and
dormancy. Latent EBV remains in the patient’s body for the rest of his
life, reactivating intermittently, but causing few problems unless the
patient’s immune system is significantly compromised.
Most people are
infected by EBV in childhood and experience few or no symptoms, even in
the acute phase of the infection. However, when the initial infection is
delayed until adolescence, EBV causes infectious mononucleosis (Mono) in
about 35 – 50% of those infected. Mono is a condition that is associated
with fatigue, fever, sore throat, swollen lymph nodes, an enlarged
spleen, and, sometimes, an enlarged liver. Those who have it are usually
symptomatic for a month or two before the initial infection resolves.
Patients
with Mono are diagnosed by their symptoms and the findings of a
complete blood count (CBC) and a
Mono test
(which tests for a heterophile antibody). A certain percentage of those
who have mono will have a negative mono test – this is especially true
with children. EBV antibodies can be used to determine whether or not
the symptoms these patients are experiencing are due to a current
infection with the EBV virus.
It can be
important to distinguish EBV from other illnesses. For instance, the
enlarged spleen of those with a Mono infection is vulnerable to rupture.
Patients who have Mono should not be involved in contact sports for
several weeks to months after infection, as a ruptured spleen can cause
a medical emergency. Also, pregnant women with symptoms of a viral
illness need to be able to distinguish a primary EBV infection (which
has not been shown to affect the baby) from a cytomegalovirus (CMV),
herpes simplex virus or toxoplasmosis infection, as these illnesses can
cause complications during the
pregnancy
and damage the fetus. It can also be important to rule out EBV and to
look for other causes for the symptoms. Patients with strep throat (a
Group A streptococcus infection), for instance, need to be identified
and treated with antibiotics. A patient may have strep throat instead of
Mono, or they may have both conditions at the same time.
There are several
EBV antibodies. They are proteins created by the body in an immune
response to different antigens (protein parts) of the Epstein-Barr
virus. They include IgM and IgG antibodies to the viral capsid antigen
(VCA), IgG antibodies to the D early antigen (EA-D), and antibodies to
the nuclear antigen (EBNA). During a primary EBV infection each of these
EBV antibodies appears independently on its own time schedule. The
VCA-IgM antibody appears first and then tends to disappear after about 4
to 6 weeks. The VCA-IgG antibody emerges, is at its maximum at 2 to 4
weeks, then drops slightly, stabilizes, and is present for life. The
EA-D antibody appears during the acute infection phase and then tends to
disappear within 3 to 6 months, but about 20% of those infected will
continue to have detectible quantities of the EA-D antibody for several
years after the EBV infection has resolved. The EBNA antibody does not
usually appear until the acute infection has resolved. It usually
develops about 2 to 4 months after the initial infection and then is
present for life. Using a combination of these EBV antibody tests, a
doctor is able to detect an EBV infection and to determine whether it is
a current, recent, or past infection.
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