Word: bacterias
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Dates: during 1990-1999
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Sometimes environmental changes help microbes move from animals to humans. Lyme disease, a bacterial infection, was largely confined to deer and wild mice until people began converting farmland into wooded suburbs -- which provided equally good habitats for the animals and the bacteria-infested ticks they carry and also brought them into contact with large numbers of people. The mice that transmit the hantavirus often take refuge in farmers' fields, barns and even homes. Air-conditioning ducts create a perfect breeding ground for Legionnaires' disease bacteria. Irrigation ditches and piles of discarded tires are ideal nesting spots for the Aedes aegypti...
...frequently stop taking antibiotics when their symptoms go away but before an infection is entirely cleared up. That suppresses susceptible microbes but allows partially resistant ones to flourish. People with viral infections sometimes demand antibiotics, even though the drugs are useless against viruses. This, too, weeds out whatever susceptible bacteria are lurking in their bodies and promotes the growth of their hardier brethren. In many countries, antibiotics are available over the counter, which lets patients diagnose and dose themselves, often inappropriately. And high-tech farmers have learned that mixing low doses of antibiotics into cattle feed makes the animals grow...
...Unlike bacteria and protozoans, which are full-fledged living cells, capable of taking in nourishment and reproducing on their own, viruses are only half alive at best. They consist of little more than a shell of protein and a bit of genetic material (DNA or its chemical cousin RNA), which contains instructions for making more viruses -- but no machinery to do the job. In order to reproduce, a virus has to invade a cell, co-opting the cell's own DNA to create a virus factory. The cell -- in an animal, a plant or even a bacterium -- can be physically...
...Unlike bacteria and protozoans, viruses are tough to fight once an infection starts. Most things that will kill a virus will also harm its host cells; thus there are only a few antiviral drugs in existence. Medicine's great weapon against viruses has always been the preventive vaccine. Starting with smallpox in the late 1700s, diseases including rabies, polio, measles and influenza were all tamed by immunization...
Newly emerging viruses, drug-resistant bacteria and a wide variety...