Acute Infectious Mononucleosis Defined

The Epstein-Barr virus (EBV), also known as human herpesvirus4, can be found in over 95% of the population, worldwide.

When EBV causes what is known as primary infection, it almost always manifests as acute infectious mononucleosis. Mononucleosis is a condition that tends to strike adolescents and young adults, and then resolves on its own. Classic signs of mononucleosis include sore throat, fever, and lymphadenopathy (swollen glands).

When young children become infected with the Epstein-Barr virus, they are often symptom-free. Even when there are symptoms, they tend to be quite mild.

Tumor Virus

But EBV doesn't always manifest as mono. The virus is also known as a human tumor virus. In fact, this is the first virus that was found to be associated with human malignancy. Some of the tumor-related conditions linked to EBV include nasopharyngeal carcinoma and Burkitt lymphoma.

History of Glandular Fever

Mononucleosis received recognition only in the late 19th century, when it was described as acute glandular fever. The illness was described as being accompanied by such symptoms as lymphadenopathy, fever, hepatosplenomegaly (enlarged spleen and liver), malaise, and abdominal discomfort and seemed to affect teens and young adults.

In 1920, Sprunt and his colleagues decided to apply the name infectious mononucleosis to cases of acute leukemia which resolved without treatment and presented with blood cells resembling blasts.

Research led to discoveries in the field in 1923 and 1932 by Downey, and then Paul and Bunnell, respectively. These findings led to more accurate diagnoses. Despite these advances, the cause of the disease remained unknown for many years.

At first, researchers didn't know that primary infections such as EBV tend to come without symptoms. They also didn't know that the virus could be found in the blood of most adults.

It wasn't until 1964 that Epstein found the first human tumor virus while looking at virus particles from a Burkitt lymphoma cell line. In 1968, Henle published a report describing the relationship between mono and EBV.

Yale University then performed a large study which gave a firm foundation to the Epstein-Barr virus as the etiologic agent of acute infectious mononucleosis.

No Symptoms

Because EBV comes with no symptoms, it's hard to pinpoint just how often people come down with a related infection that causes symptoms. However, it is believed that by the age of 5 years, around half of the United States population is infected with the virus.

In childhood, symptoms caused by the virus are rare, but there may be a slight elevation in liver function test results. On the other hand, EBV contracted during adolescence may come with the symptoms of mononucleosis.