Epstein-Barr Virus Health Article

Definition

Epstein-Barr Virus, or EBV, is the name given to a member of the herpesvirus family that is associated with a variety of illnesses—from infectious mononucleosis (IM), to nasal-pharyngeal cancer, and Burkitt's lymphoma.

Description

Herpesviruses have long been known. The name actually comes from the Greek adjective herpestes, which means creeping. Many herpesvirus species appear to establish a life-long presence in the human body, remaining dormant for long periods and becoming active for some, often inexplicable, reason. EBV is only one of several members of the Herpesvirus family that have similar traits. Others include varicella zoster virus—the cause of both chickenpox and shingles—, and the herpes simplex virus responsible for both cold sores and genital herpes. EBV is usually transmitted through saliva but not blood, and is not normally an airborne infection.

EBV occurs in nearly all regions of the world, and is considered among the most common infectious viruses known to humankind. In the United States, the Center for Disease Control (CDC) estimates that 95% of adult Americans between the ages of 35 and 40 years have been infected, but it is less prevalent in children and teenagers. This pattern of infecting adults more than children persists throughout other prosperous western countries, but does not hold true in underdeveloped regions such as Africa and Asia. In Africa, most children have been infected by EBV by the age of three years

Individuals with EBV infections typically show some elevation in the white blood cell count and a noticeable increase in lymphocytes—white blood cells associated with the immune response of the body. IM is a time-limited infection that usually lasts from one to two months. Symptoms include fever, malaise, sore throat, swollen glands and (sometimes) swollen spleen and/or liver. EBV infections that lead to Burkitt's lymphoma in Africa typically affect the jaw and mouth area, while the (very rare) incidences of Burkitt's lymphoma found in developed countries are more apt to manifest tumors in the abdominal region. Nasopharyngeal cancer is uncommon in the West but more prevalent in the Far East. It affects more men than women, and usually occurs between the ages of 40 and 50 years.

Causes

EBV has been linked to IM in the Western world for decades. It has also become associated consistently with nasopharyngeal cancers in Asia (especially China) and Burkitt's lymphoma in Africa and Papua New Guinea. According to the CDC, EBV is not the sole cause of these two malignancies, but does play an important role in the development of both cancers. The mechanism that allows Epstein-Barr Virus to at least help in producing such diverse illnesses in diverse regions of the world has been the subject of increasing research and scrutiny.

It is known that, once it infects a person, EBV is one of the herpesviruses that remain in the human body for life. Under certain, still not-understood conditions, it alters white blood cells normally associated with the immune system, changing B lymphocytes (those normally associated with making antibodies), and causing them to reproduce rampantly. EBV can bind to these white blood cells to produce a solid mass made up of B lymphocytes— called Burkitt's lymphoma—or to the mucous membranes of the mouth and nose and cause nasopharyngeal cancer. Since Burkitt's lymphoma typically occurs in people living in moist, tropical climates, the same regions where people usually contract malaria, it has been speculated that the immune system is altered by its response to malaria. When EBV infection occurs, the altered immune system's reaction is the production of a tumor.

Special concerns

Though studies about the hereditary tendency of abnormal cell development after EBV infection are incomplete, some studies have shown it to be a hereditary trait based upon the X chromosome.