Emerging viruses: the evolution of viruses and viral diseases

Article Abstract:

In May 1989, the National Institute of Allergy and Infectious Diseases, the Fogarty International Center of the National Institute for Health, and Rockefeller University jointly sponsored a conference titled 'Emerging viruses: the evolution of viruses and viral diseases.' The purpose of the conference was to discuss the emergence, geographical distribution and genetic variation of new viruses and viral diseases. The pattern of emergence of infectious diseases can follow the pattern of human movement. This is illustrated by the introduction of syphilis into Europe and smallpox into America when travel across the Atlantic ocean first became possible. African slave trade may have been responsible for the introduction of yellow fever in the New World. Slave ships probably carried the causative agent of yellow fever, Aedes aegypti, in their ballast water. The appearance of hemorrhagic fever in Southeast Asia is thought to have been caused by human migration to cities with open water storage, favoring the growth of the causative agent. Today, two examples of emerging viruses with worldwide distribution include influenza (producing respiratory symptoms, and carried by fowl and pigs) and human immunodeficiency virus (AIDS-related complex). Genetic mutation (a nonlethal alteration in the viral genome) and recombination (the combining of a piece of genetic material from one virus with the genetic material of another virus) are common ways in which new viral strains, and thus emergent diseases, can develop. The development of drug treatments for emergent diseases cannot begin until after the new disease develops. Therefore, it is recommended that surveillance programs for the detection of new diseases be developed in certain regions of the world, such as tropical rain forests and densely populated areas, were the possibility of disease emergence is greatest. (Consumer Summary produced by Reliance Medical Information, Inc.)

Viruses, Evolution (Biology)

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Excretion of the Epstein-Barr virus from the genital tract of men

Article Abstract:

The Epstein-Barr virus (EBV) belongs to the same family of viruses as the herpes simplex virus. EBV is a common virus and causes mononucleosis (also called mono or the kissing disease). Infection with EBV can be fatal in patients who already have diseases that attack the immune system (the body's natural defense system for fighting infection). Patients with AIDS are among this vulnerable group of immunocompromised patients. The EBV is also closely linked to two different types of cancer: nasopharyngeal carcinoma (cancer of the nose and throat) and Burkitt's lymphoma. The virus can be transmitted in human saliva and it has been found in the female genital tract of infected women, indicating that it may be transmitted through sexual contact. Until recently, EBV had not been found in the genital tract of men infected with the virus. However, with the aid of a new and very sensitive laboratory procedure, EBV has been found in the semen of infected men. This new laboratory technique, called the polymerase chain reaction (PCR), can identify very small amounts of viral DNA (genetic material) in blood, semen, urine, mucous, and body tissues. Using this technique, EBV was identified in 10 of 21 men who provided semen specimens. (The men were attending a clinic for sexually transmitted diseases.) These findings lend further support to the theory that EBV can be transmitted through sexual contact. (Consumer Summary produced by Reliance Medical Information, Inc.)

Polymerase chain reaction, Semen, Epstein-Barr virus

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Viral lower respiratory tract infections in Filipino children

Article Abstract:

Pneumonia kills four million children a year in developing countries. Bacterial infections have been thought to be the major cause of this, although viral infections are known to cause many cases of pneumonia in developed countries. Preexisting viral infections may predispose children to bacterial infections, but studies of the incidence of viral infections in developing countries have been limited. A group of 300 Filipino children who were ill with lower respiratory tract infections was studied to determine the extent and type of viral infections in that population, using modern sensitive techniques. Fifty-two percent of children had viral infections, with measles being present in over 21 percent of the children tested. Other viral infections in the children included influenza A; parainfluenza types 1, 2, and 3; respiratory syncytial virus; influenza B; enteroviruses; adenoviruses; herpes simplex; and cytomegalovirus, in descending order of incidence. The presence of influenza A or B was associated with milder forms of lower respiratory tract infection, while measles virus was associated with more severe disease. However, differing socioeconomic status, indicated by relative nutritional status, may underlie the association of these infections with severity of disease. Bacterial causes of infection in these children will be reported separately. (Consumer Summary produced by Reliance Medical Information, Inc.)

Respiratory tract infections, Philippines, Viral pneumonia

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