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The mono test is used to help
determine whether a patient has infectious mononucleosis. It is
frequently ordered along with a CBC (complete blood
count). The CBC is used to determine whether the number of white
blood cells (WBCs) is elevated and whether a significant number of
reactive lymphocytes (a type of WBC) is present. A strep test may be
ordered with the mono test to determine whether a person’s sore throat
is due to a streptococcal infection instead of or in addition to
mononucleosis.
Approximately 10% of
mononucleosis syndromes have a mono test which is initially negative. If
you still suspect mono, you may order a repeat test in a week or so to
see if heterophile antibodies have developed and/or order
EBV antibodies to help confirm or rule out the presence of a current
EBV infection.
The heterophile antibodies
is a human antibody that can attach to (agglutinate) the red blood cells
of different animals. The mono test uses an antigen derived from the red
blood cells of horses. The mixture of this test material with patient
blood causes a clumping reaction if the patient has mononucleosis.
The mono test is primarily
ordered when an adolescent patient has symptoms such as fever, headache,
swollen glands, and fatigue that the doctor suspects are due to
infectious mononucleosis. The test may be repeated when it is initially
negative but suspicion of mono remains high.
If you have a positive mono
test, an increased number of white blood cells, reactive lymphocytes,
and symptoms of mononucleosis, then they will be diagnosed with
infectious mononucleosis. If symptoms and reactive lymphocytes are
present but the mono test is negative, then it may be too early to
detect the heterophile antibodies or the affected patient may be in the
small number of people who do not make heterophile antibodies. Other EBV
antibodies and/or a repeat mono test may be performed to help confirm or
rule out the mononucleosis diagnosis.
Most infants and young
children will not make heterophile antibodies, so they will have
negative mono tests even when infected with EBV. This population is
rarely tested, however, because they do not usually have symptoms of
infectious mononucleosis.
Patients with negative mono
tests and few or no reactive lymphocytes may be infected by another
microorganism that is causing mono-like symptoms (such as a
cytomegalovirus (CMV) or toxoplasmosis). If the infection occurs during
pregnancy, it can be important to determine the cause, as some of the
mono-like infections (but not EBV infection) have been associated with
pregnancy complications and damage to the fetus. It is also important to
identify strep throat, whenever present, because it should be treated
promptly with antibiotics.
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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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