©2018 Mahoning Valley Water Inc.  Waterborne Bacteria Now Recognized as a Health Threat      Once dismissed as threatening little more than a stomach ache, microscopic waterborne bugs are increasingly turning deadly, forcing health officials to shift priorities as they try to make drinking water safe for a changing population.      For years, the Environmental Protection Agency (EPA) has focused on potential cancer- causing chemicals as the main drinking water threat.  Now, water agencies and federal health officials concede the more immediate concern is waterborne bacteria, parasites, and viruses such as cryptosporidium and giardia, some of which were largely ignored, or even unknown, until a few years ago.       The health threat became apparent in 1993 when 100 people - most of them elderly or otherwise susceptible to illness - died in Milwaukee in an outbreak of cryptosporidium in the city's drinking water.  More than 400 others became ill.      In most healthy people, the damage is limited to a brief bout of intestinal discomfort, sometimes mistaken for the flu.  But for those whose immune systems cannot ward off bacterial attack - cancer patients and the elderly or those suffering from AIDS, for example - drinking water can become deadly say health officials.      "It is a serious issue, an emerging threat," said EPA administrator Carol Browner.  "We think it needs significant focus."      Some of these pathogens are still mostly a mystery to health experts.  Some, like cryptosporidium, are immune to standard chlorine purification treatment.  The EPA has already initiated a five-year, $50 million effort to learn more about microbial pollution and how it can best be treated.       According to the Centers for Disease Control and Prevention, between 900 and 1,000 people a year die and another 1 million people become sick from microbial illnesses from drinking water.  Other estimates have put deaths as high as 1,200 and estimated illnesses at more than 7 million, because many are never reported to doctors. U.S. Water New Sept 1996 Crypto Test Volunteers Post 62% Infection Rate      Studies recently conducted by researchers at the University of Texas School of Public Health, Houston, TX, found a 62 percent infection rate of cryptosporidiosis in healthy adults, according to New Waves.      The study led by Herbert DuPont and Cynthia Chappell from the University's Center for Infectious Diseases, involved providing volunteers with doses of cryptosporidium ranging from a low of 30 to 1 million oocysts.  More than 62% of the volunteers became infected, regardless of dose levels.  A level of 132 oocysts caused about half the volunteers to become infected.  In contrast, it takes as many as 10 million cholera bacteria for a healthy person to become infected.      Chappell says the studies help explain why so many people became ill during a Crypto outbreak in Milwaukee, WI, in 1993. MAHONING VALLEY WATER