tailieunhanh - Chapter 174. Epstein-Barr Virus Infections, Including Infectious Mononucleosis

Epstein-Barr virus (EBV) is the cause of heterophile-positive infectious mononucleosis (IM), which is characterized by fever, sore throat, lymphadenopathy, and atypical lymphocytosis. EBV is also associated with several human tumors, including nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's disease, and (in patients with immunodeficiencies) B cell lymphoma. The virus, a member of the family Herpesviridae, consists of a linear DNA core surrounded by a nucleocapsid and an envelope that contains glycoproteins. The two types of EBV that are widely prevalent in nature are not distinguishable by conventional serologic tests. Epidemiology EBV infections occur worldwide. These infections are most common in. | Chapter 174. Epstein-Barr Virus Infections Including Infectious Mononucleosis Definition Epstein-Barr virus EBV is the cause of heterophile-positive infectious mononucleosis IM which is characterized by fever sore throat lymphadenopathy and atypical lymphocytosis. EBV is also associated with several human tumors including nasopharyngeal carcinoma Burkitt s lymphoma Hodgkin s disease and in patients with immunodeficiencies B cell lymphoma. The virus a member of the family Herpesviridae consists of a linear DNA core surrounded by a nucleocapsid and an envelope that contains glycoproteins. The two types of EBV that are widely prevalent in nature are not distinguishable by conventional serologic tests. Epidemiology EBV infections occur worldwide. These infections are most common in early childhood with a second peak during late adolescence. By adulthood more than 90 of individuals have been infected and have antibodies to the virus. IM is usually a disease of young adults. In lower socioeconomic groups and in areas of the world with lower standards of hygiene . developing countries EBV tends to infect children at an early age and symptomatic IM is uncommon. In areas with higher standards of hygiene infection with EBV is often delayed until adulthood and IM is more prevalent. EBV is spread by contact with oral secretions. The virus is frequently transmitted from asymptomatic adults to infants and among young adults by transfer of saliva during kissing. Transmission by less intimate contact is rare. EBV has been transmitted by blood transfusion and by bone marrow transplantation. More than 90 of asymptomatic seropositive individuals shed the virus in oropharyngeal secretions. Shedding is increased in immunocompromised patients and those with IM. Pathogenesis EBV is transmitted by salivary secretions. The virus infects the epithelium of the oropharynx and the salivary glands and is shed from these cells. While B cells may become infected after contact with epithelial .