<unk> , peripheral smear, high power showing reactive lymphocytes Splenomegaly due to<unk>  resulting in a subcapsular hematoma Splenomegaly due to<unk>  resulting in a subcapsular hematoma Diagnostic modalities for<unk>  include: * Person's age, with highest risk at 10 to 30 years. * Medical history, such as close contact with other people with<unk> , and the presence and time of onset of<unk> -like symptoms" such as fever and sore throat. * Physical examination, including palpation of any enlarged lymph nodes in the neck, or enlarged spleen. * The heterophile antibody test is a screening test that gives results within a day, but has significantly less than full sensitivity (70–92%) in the first two weeks after clinical symptoms begin. * Serological tests take longer time than the heterophile antibody test, but are more accurate. Physical examination The presence of an enlarged spleen, and swollen posterior cervical, axillary, and inguinal lymph nodes are the most useful to suspect a diagnosis of<unk> . On the other hand, the absence of swollen cervical lymph nodes and fatigue are the most useful to dismiss the idea of<unk>  as the correct diagnosis. The insensitivity of the physical examination in detecting an enlarged spleen means it should not be used as evidence against<unk> . A physical examination may also show petechiae in the palate. Heterophile antibody test The heterophile antibody test, or monospot test, works by agglutination of red blood cells from guinea pigs, sheep and horses. This test is specific but not particularly sensitive (with a false-negative rate of as high as 25% in the first week, 5–10% in the second, and 5% in the third). About 90% of diagnosed people have heterophile antibodies by week 3, disappearing in under a year. The antibodies involved in the test do not interact with the Epstein–Barr virus or any of its antigens. The monospot test is not recommended for general use by the CDC due to its poor accuracy. Serology Serologic tests detect antibodies directed against the Epstein–Barr virus.<unk> munoglobulin G (IgG), when positive, mainly reflects a past infection, whereas<unk> munoglobulin M (IgM) mainly reflects a current infection. EBV-targeting antibodies can also be classified according to which part of the virus they bind to: * Viral capsid antigen (VCA): :*Anti-VCA IgM appear early after infection, and usually, disappear within 4 to 6 weeks. :*Anti-VCA IgG appears in the acute phase of EBV infection, reaches a maximum at 2 to 4 weeks after onset of symptoms and thereafter declines slightly and persists for the rest of a person’s life. * Early antigen (EA) :*Anti-EA IgG appears in the acute phase of illness and disappears after 3 to 6 months. It is associated with having an active infection. Yet, 20% of people may have antibodies against EA for years despite having no other sign of infection. * EBV nuclear antigen (EBNA) :*Antibody to EBNA slowly appears 2 to 4 months after the onset of symptoms and persists for the rest of a person’s life. When negative, these tests are more accurate than the heterophile antibody test in ruling out<unk> . When positive, they feature similar specificity to the heterophile antibody test. Therefore, these tests are useful for diagnosing<unk>  in people with highly suggestive symptoms and a negative heterophile antibody test. Other tests * Epstein–Barr nuclear antigen detection. While it is not normally recognizable until several weeks into the disease and is useful for distinguishing between a recent-onset of<unk>  and symptoms caused by a previous infection. * Elevated hepatic transaminase levels are highly suggestive of<unk> , occurring in up to 50% of people. * By blood film, one diagnostic criterion for<unk>  is the presence of 50% lymphocytes with at least 10% atypical lymphocytes (large, irregular nuclei), while the person also has fever, pharyngitis, and swollen lymph nodes. The atypical lymphocytes resembled monocytes when they were first discovered, thus the term<unk> " was coined. * A fibrin ring granuloma may be present. Differential diagnosis About 10% of people who present a clinical picture of<unk>  do not have an acute Epstein–Barr-virus infection. A differential diagnosis of acute<unk>  needs to take into consideration acute cytomegalovirus infection and Toxoplasma gondii<unk> . Because their management is much the same, it is not always helpful, or possible, to distinguish between Epstein–Barr-virus<unk>  and cytomegalovirus infection. However, in pregnant women, differentiation of<unk>  from toxoplasmosis is<unk> portant, since it is associated with significant consequences for the fetus. Acute HIV infection can mimic signs similar to those of<unk> , and tests should be performed for pregnant women for the same reason as toxoplasmosis. People with<unk>  are sometimes misdiagnosed with a streptococcal pharyngitis (because of the symptoms of fever, pharyngitis and adenopathy) and are given antibiotics such as ampicillin or amoxicillin as treatment. Other conditions from which to distinguish<unk>  include leukemia, tonsillitis, diphtheria, common cold and influenza (flu).
Infectious mononucleosis
Chronic lymphocytic leukemia
Adult-onset Still's disease
Streptococcal pharyngitis
Post-Ebola virus syndrome
Acute lymphoblastic leukemia
Typhoid fever
Peritonsillar abscess