The symptoms of mononucleosis really are a sore throat, fever, fatigue, weight loss, malaise, pharyngeal inflammation, vomiting, petechiae and lack of appetite.

Common signs include lymphadenopathy (enlarged lymph nodes), splenomegaly (enlarged spleen), hepatitis (is best described as inflammation of hepatocytes—cells in the liver) and hemolysis (the bursting of red blood cells).

Often, If the symptoms of mononucleosis are not apparent to begin with 48 hours of possible viral infection, then mononucleosis will never be present. Older adults are more unlikely that to possess a sore throat or lymphadenopathy, but are instead more prone to present with hepatomegaly [enlargement of many liver] and jaundice. Rarer indicators include thrombocytopenia [lower stages of platelets], with or without pancytopenia (lower stages of every type of blood cells), splenic rupture, splenic hemorrhage, upper airway obstruction, pericarditis and pneumonitis. Another rare manifestation of mononucleosis is erythema multiforme.

Mononucleosis is often amid secondary cold agglutinin disease—an autoimmune disease during which abnormal circulating antibodies directed against red blood cells can lead into a sort of autoimmune hemolytic anemia. The cold agglutinin detected is of anti-i specificity. Patients with the symptoms of mononucleosis are sometimes misdiagnosed with a streptococcal pharyngitis [because of the classical clinical triad of fever, pharyngitis and adenopathy] and therefore are given antibiotics comparable to ampicillin or amoxicillin as treatment. 

Some studies indicate that approximately 80–90% of patients with acute Epstein–Barr virus infection treated with such antibiotics arrive at a red, diffuse rash cuz of the symptoms of mononucleosis.

The symptoms of mononucleosis occurs with infection by the Epstein–Barr virus. An equivalent condition might be caused by cytomegalovirus, but that you gives a negative at the heterophile antibody test. Due to this, some sources say that infectious mononucleosis is caused from the Epstein–Barr virus.

The infection is spread via saliva and actually has an incubation time period 4–7 weeks. The symptoms of mononucleosis usually persist for 2–3 weeks, but fatigue is often more prolonged.

Effort someone together with the virus stays contagious after symptoms are gone is uncertain, but it is thought that the most contagious period lasts about 6 weeks after the onset of symptoms. Some studies demonstrates that someone can spread the infection for a number of months when symptoms are completely gone, only one study indicating given that 18 months.

The virus replicates first within epithelial cells in the pharynx (which causes pharyngitis, or sore throat), and later primarily within B cells (which are invaded via their CD21). Host immune response involves cytotoxic (CD8-positive) T cells against infected B lymphocytes, ending in enlarged atypical lymphocytes (Downey cells).

Whenever the infection is acute (recent onset, compared to chronic), heterophile antibodies are produced.

Exudative pharyngitis inside a person with The symptoms of mononucleosis

Cervical lymphadenopathy in someone with infectious mononucleosis

Essentially the most frequently used diagnostic criterion will be the presence of 50% lymphocytes with at least 10% atypical lymphocytes (large, irregular nuclei), as the person has also fever, pharyngitis and adenopathy. Furthermore, it's probably confirmed using a serological test. The atypical lymphocytes resembled monocytes if they were first discovered, thus the acronym The symptoms of mononucleosis was coined. Diagnostic tests are being used to substantiate infectious mononucleosis however the disease should really be suspected from symptoms prior to a results from hematology. These criteria are specific; however, they are not particularly sensitive and therefore are more used by research compared to clinical use. Only half the patients presenting in the symptoms held by mononucleosis along with a positive heterophile antibody test (monospot test) match the entire criteria. One key procedure is usually to differentiate between infectious mononucleosis and mononucleosis-like symptoms.

There has also been few studies on infectious mononucleosis in a primary care environment, the most of which studied 700 patients, of which 15 were found to have mononucleosis at the heterophile antibody test. More useful within a diagnostic sense are classified as the signs and symptoms themselves. The presence of splenomegaly, posterior cervical adenopathy, axillary adenopathy, and inguinal adenopathy are the very useful to suspect a critique of infectious mononucleosis. However, the absence of cervical adenopathy and fatigue would be the most helpful to challenge the idea of infectious mononucleosis because the correct diagnosis. The insensitivity of a typical physical examination in detecting splenomegaly ways that it must not be applied as evidence against infectious mononucleosis.

In the past the commonest test for diagnosing infectious mononucleosis was the heterophile antibody test which involves testing heterophile antibodies by agglutination of guinea pig, sheep and horse red blood cells. As with the aforementioned criteria, this test is particular although not particularly sensitive (that has a false-negative rate of as high as 25% ahead of time, 5–10% under the second and 5% inside the third). 90% of patients have The symptoms of mononucleosis by week 3, disappearing in under 1 year. The antibodies involved with the test do not connect to the Epstein–Barr virus or many from the antigens.

More recently, tests that have been more sensitive have been developed for example the Immunoglobulin G (IgG) and Immunoglobulin M (IgM) tests and the symptoms of mononucleosis. IgG, when positive, reflects a past infection, whereas IgM reflects an active infection. When negative, these tests are usually more accurate in ruling out infectious mononucleosis. However, when positive, they feature similar sensitivities to the heterophile antibody test. Therefore, these tests are helpful for diagnosing infectious mononucleosis in people with highly suggestive symptoms and a negative heterophile antibody test. Another test searches for the Epstein–Barr nuclear antigen, though it will never be normally recognizable until several weeks into the disease, and it is helpful for distinguishing between a recent-onset of infectious mononucleosis and symptoms attributable to a previous infection. Elevated hepatic transaminase levels is highly suggestive of infectious mononucleosis, occurring in as much as 50% of patients.

A fibrin ring granuloma might be present of the symptoms of mononucleosis.