The Nation’s Meat Supply : Food Poisoning Under a Microscope

The recent outbreak of Escherichia coli 0157:H7 in the Western United States perfectly illustrates the challenges involved in ensuring a safe and wholesome food supply. As recently as 1982 this bacterial strain was unknown to science. Researchers and health officials agree that pathogenic bacteria are changing, much in the same way humans are evolving. The organisms are getting stronger and are constantly adapting to their environment. At the same time, Americans are living longer, and the percentage of the United States population that is at acute risk for infection from these organisms is increasing. The E. coli 0157:H7 incident, with most of the illnesses clustered among the young and the elderly, shows just how opportunistic these bacteria can be when introduced into the food supply. However, E. coli 0157:H7 is one of a number of food-borne illnesses that can infect normal, healthy adults and not just infants or the infirm. Some of the major problems, according to the National Academy of Sciences, include: * Salmonella. There are thousands of strains of this bacteria, ranging in toxicity and including the variety that causes typhoid fever. Salmonella organisms are found throughout the environment and are considered ubiquitous by science. Nevertheless, harmful strains of Salmonella are frequently associated with raw foods. Once present, the bacteria multiply quickly if not destroyed by refrigeration, freezing or cooking. It is still not known how many salmonella need to be present in food to infect adults and cause illness. An estimated 2 million cases of Salmonellosis occur in the United States each year. Symptoms include fever, nausea, diarrhea, vomiting and abdominal cramps. * Camphylobacter. The first case of food-borne Camphylobacteriosis was reported to the Centers for Disease Control and Prevention in 1978. Since then, this pathogen is believed to rival Salmonella for the number of illnesses caused each year. Camphylobacter may be easier to control than Salmonella but could still multiply if present in food that is improperly refrigerated or prepared. Symptoms are similar to Salmonellosis except that advanced cases can cause relapsing colitis. * Listeria. Again, this bacteria may be present in a wide variety of foods but is most likely to cause illness in high-risk individuals, particularly pregnant women. The largest outbreak of Listeriosis occurred in Los Angeles County in 1985 and was linked to a Mexican-style soft cheese made from unpasteurized milk. Last year, health officials warned pregnant women to avoid consumption of deli foods, soft cheeses and undercooked chicken because of the likely presence of Listeriosis monocytogenes. Symptoms include meningitis, septicemia, brain abscess, pneumonia and hepatitis. * Staphylococcus. The National Academy of Sciences described Staphylococcus as one of the “most frequent causes of food poisoning.” Humans infected with the bacteria who then handle food are the most likely cause of illness. Unlike some of the other pathogens, Staphylococcus must be present in high levels for the food to cause illness. Symptoms are similar to Salmonellosis. * Shigella. Humans are the most likely source of Shigella bacteria, small doses of which can cause illness. An estimated 300,000 cases of Shigellosis occur annually in this country. “Most outbreaks of food-borne Shigellosis result from contamination of raw or previously cooked foods during preparation by an infected food handler with poor personal hygiene,” the National Academy of Sciences reported. Symptoms are similar to Salmonellosis. * Vibrio. There are numerous strains of this bacterial family, including the one that causes cholera. Since 1991, California has required that all retail outlets selling oysters from the Gulf of Mexico post warnings that the shellfish may contain Vibrio vulnificus , a bacteria with a high fatality rate in those infected. Most susceptible to V. vulnificus are people with liver diseases, cancer and other chronic illnesses such as diabetes or AIDS. Symptoms are similar to Salmonellosis but can lead to septicemia. Death has occurred within two days.