Infectious mononucleosis, commonly known as mono, is a viral infection often caused by the Epstein-Barr Virus (EBV). Its symptoms can mimic other common illnesses, so accurate diagnosis through specific testing is important. This confirms the infection and rules out other conditions.
Symptoms Indicating a Test
Individuals often seek testing for mono when experiencing characteristic symptoms. These include persistent fatigue, a sore throat, fever, and swollen lymph nodes, in the neck and armpits. A swollen spleen or liver may also be present. Since these symptoms can overlap with other infections, testing helps differentiate mono from other illnesses.
Primary Diagnostic Tests
Diagnosing infectious mononucleosis often involves a combination of laboratory tests. These tests identify specific blood markers indicating an active or past Epstein-Barr virus infection. Primary methods include the Monospot test, specific EBV antibody tests, and a complete blood count.
Monospot Test
The Monospot test, also known as the heterophile antibody test, is a rapid screening tool for mono. It detects heterophile antibodies produced by the immune system in response to an EBV infection; results often available quickly. However, the Monospot test has limitations. It can produce false-negative results, especially if performed too early or in young children. The Centers for Disease Control and Prevention (CDC) does not recommend it as a definitive diagnostic method due to its variable sensitivity.
EBV Antibody Tests
Epstein-Barr Virus (EBV) antibody tests are more specific, providing detailed information about the infection stage. They identify different antibodies produced against EBV. Viral Capsid Antigen (VCA) IgM antibodies usually indicate a current or very recent primary EBV infection. VCA IgG antibodies develop during acute infection and generally persist for life, signaling a past infection, while EBV Nuclear Antigen (EBNA) IgG antibodies typically appear weeks to months after initial infection, remaining detectable for years. The pattern of these specific antibodies helps healthcare providers determine if an infection is acute, recent, or past.
Complete Blood Count (CBC)
A complete blood count (CBC) offers supportive evidence for a mono diagnosis, though it is not diagnostic on its own. A CBC may show an increased number of white blood cells, particularly lymphocytes, and the presence of atypical lymphocytes. Atypical lymphocytes are white blood cells the body produces to fight infections. While these findings support the suspicion of mono, they are also associated with other conditions, requiring further specific testing for confirmation.
Interpreting Test Outcomes
A positive Monospot test in a person with mono-like symptoms supports an infectious mononucleosis diagnosis. However, a negative Monospot result does not always exclude mono, especially if performed early in the illness; in such cases, or when symptoms persist, further EBV-specific antibody testing is often recommended. For EBV antibody tests, the pattern of antibodies helps determine the infection stage. The presence of VCA IgM antibodies, especially with negative EBNA IgG, suggests an acute or recent infection, while positive VCA IgG and EBNA IgG with negative VCA IgM indicates a past infection and immunity. Conflicting or indeterminate results can occur, requiring healthcare providers to use these alongside clinical symptoms and medical history for an informed diagnosis, sometimes with follow-up testing.
Life After a Mono Diagnosis
Once diagnosed, management of infectious mononucleosis primarily focuses on supportive care. Rest helps the body fight infection and manage fatigue. Staying well-hydrated and using over-the-counter pain relievers can ease fever, sore throat, and muscle aches. Avoiding strenuous activities, particularly contact sports, is important due to the potential for an enlarged spleen and risk of rupture. This caution is advised until a healthcare provider confirms the spleen has returned to a normal size.