Word: viruses
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Dates: during 1980-1989
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Although acute infections like influenza kill thousands each year, most people defeat their tiny attackers. Still, they may suffer while the battle is being waged. Indeed, many of the typical symptoms of infection -- fever, chills, itchy rashes, localized swelling -- are due less to the virus than to the vigorous activity of the immune system. However, once the body has created a population of antibody-producing B cells designed to combat a specific virus, immunity to that virus often lasts for decades, or even a lifetime. Then why does the common cold return again and again? One reason, scientists explain...
...between attacks, the latent herpes viruses hide out in the nerve centers, or ganglia. There they are so quiescent, expressing only five to ten of their 70 genes, that the immune system fails to detect them. Occasionally, for reasons that are poorly understood but that usually involve stress, fatigue, sexual activity and even sunburn, the immune system can no longer keep the hibernating viruses in check; they awaken, reproduce and head for the skin. "As long as the virus remains latent in the ganglia, it remains shielded," says Bernard Roizman, a leading herpes researcher at the University of Chicago...
...members of the troublesome herpes family. Herpes zoster, which causes chicken pox, sometimes hides in nerve cells, where no drug or antibody can reach it. Years after the pox attack, usually in middle or old age, zoster can sneak out and cause excruciating attacks of shingles. The Epstein-Barr virus, a herpes family member that causes infectious mononucleosis, follows a similar strategy, though its hiding place is not in the nerves but in the B cells, the very cells that make antibodies to viruses. In contrast to the dormant staying power of herpes viruses, the persistent hepatitis B virus...
Many of these chronic viruses are now being linked to cancer. A landmark study conducted in Taiwan between 1975 and 1978 by Dr. R. Palmer Beasley, now at the University of California, San Francisco, found a striking connection between chronic hepatitis B infection and liver cancer, a leading killer in the Third World. "Someone infected with hepatitis B has 100 times the normal risk of developing liver cancer," says Beasley, "and that's being conservative." The Epstein-Barr virus has been associated with a couple of types of cancer. In Central Africa and New Guinea, it has been linked...
Several such events or "co-factors" have been suggested in the papillomavirus-cervical cancer connection. They include smoking (which appears to increase risk of this cancer fourfold), poor hygiene and concurrent infection with the herpes simplex virus type 2. Says Dr. Carlos Lopez of the Centers for Disease Control: "Maybe one virus is the instigator and the other is the promoter...