Microbiology
Summary
Epstein-Barr virus (EBV), a member of the Herpesviridae family, is a DNA virus primarily transmitted through saliva. To initiate infection, the EBV envelope glycoprotein binds to the CD21 membrane protein of B-cells. Clinically, EBV is responsible for mononucleosis, which presents with hallmark symptoms such as fever, pharyngitis with tonsillar exudate, and painful lymphadenopathy in the posterior cervical region. The immune response to EBV includes peripheral lymphocytosis, characterized by the presence of reactive lymphocytes (Downey cells). Lymphocyte proliferation in lymphoid tissue can lead to splenomegaly and enlarged lymph nodes.
Further complexities of EBV infections arise from its ability to remain latent in B-cells. EBV is also associated with several more severe conditions, ranging from Hodgkin's and non-Hodgkin's lymphoma to nasopharyngeal carcinoma and oral hairy leukoplakia, which is especially prevalent in HIV patients. Diagnosing acute EBV infections can be expedited using the monospot test. Due to the risk of splenic rupture, patients diagnosed with infectious mononucleosis are advised to avoid contact sports. When patients with symptoms of mononucleosis are incorrectly diagnosed and treated with penicillin or amoxicillin for suspected streptococcal pharyngitis, a maculopapular rash may develop.
Lesson Outline
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FAQs
The Epstein-Barr virus (EBV) is a part of the Herpesviridae family. This family of viruses contains double-stranded DNA, and is known for causing diseases such as infectious mononucleosis, often referred to as the "kissing disease."
EBV is transmitted via saliva and infects B-cells in the lymphatic system, leading to symptoms such as pharyngitis and lymphadenopathy. The body responds to this infection by increasing production of CD8+ cytotoxic T-cells and reactive lymphocytes, the elevated levels of which can lead to infectious mononucleosis.
While the most common condition associated with EBV is infectious mononucleosis, chronic or severe infections can lead to other more serious conditions. These include certain types of lymphomas like B-cell lymphoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma, and Burkitt lymphoma. EBV is also linked to nasopharyngeal carcinoma and, in individuals with a weakened immune system (like those with HIV), oral hairy leukoplakia.
Generally, individuals who have had an EBV infection develop immunity afterwards. However, the virus can remain dormant in the body and reactivate at later stages, especially in individuals with weakened immune systems. Reactivation of the virus does not usually cause symptoms in healthy individuals, but in immunocompromised patients, it can lead to serious conditions such as lymphomas or oral hairy leukoplakia.
