Contact: Maridith Geuder
New and emerging disease agents lurking in 21st century food products may be fostered, in part, by a combination of human activities and microbe adaptability.
Douglas L. Marshall, a food scientist at Mississippi State University, also is warning that many disease-causing microbes are yet to be discovered. A professor in the department of food science, nutrition and health promotion, Marshall is a regular consultant to the National Institutes of Health, World Health Organization and related agencies.
As director of an MSU research program seeking methods to rapidly detect and control foodborne pathogens, he recently was asked to be keynote speaker for a European gathering of the International Committee on Food Microbiology and Hygiene.
"We can look at the proliferation of diseases such as West Nile virus and severe acute respiratory syndrome (SARS) and see the dangers of new infectious diseases," he said in a recent campus interview that included several major points of his remarks to ICFMH members.
"There are scientific journals devoted entirely to research about these issues," he observed. "One recent example is the emergence of multi-drug resistant salmonella."
Most often associated with poultry and eggs, salmonella can cause severe intestinal distress. "In eggs, it used to be the rule of thumb that those with intact shells were sterile," Marshall said.
A new strain of salmonella has changed that premise. "Even with an intact shell, the egg is not protected," he explained. "We've seen an explosion of salmonella cases over the last 20 years from raw and undercooked eggs."
He said food scientists also are alarmed by new varieties of E. coli, a bacterium that normally lives in the intestines of healthy humans but also can produce deadly effects. There are many others, he added.
Marshall's lab focuses on the deadly vibrios, bacteria found primarily in shellfish. Using its Latin-based scientific name, he said vibrio vulnificus "is the most lethal food-borne pathogen that we know of, with nearly a 50 percent mortality rate."
While microorganisms such as these "have been around a long time," human activity is creating environments conducive to their flourishing, Marshall said. "Our overuse of antibiotics, for example, reduces the natural competitors for some of these organisms, and they adapt," he added.
Citing another example, Marshall said global warming has extended to Alaska the environmental range of what formerly were known as "warm-water bacteria." Adding urgency to this development is an increased proportion of vulnerable, higher-risk persons--growing populations of the elderly and those with chronic conditions, as well as residents of less developed countries with a history of poor sanitation and hygiene.
"I'm concerned that we continue to race to adapt new technologies that may contribute to emerging pathogens," Marshall cautioned.
Marshall said the MSU lab is keeping an especially vigilant eye on an intervention for E. coli that's used to treat cattle prior to slaughter.
"If some of these organisms survive, we want to know what their potential is for causing harm to humans," he said. "If a microorganism is stressed but not killed, it has the potential to adapt, and the survivors may be even worse."
For the average consumer, basic, common-sense precautions continue to be the best line of defense. Cooking food thoroughly and using old-fashioned soap and water for hand washing continue to be strongly recommended, he emphasized.
But even here, Marshall issued a final cautionary.
"There is an overuse of antibacterial soaps," he said. "Washing your hands carefully with regular soap and water is a fantastic intervention, and one of your best defenses."
NEWS EDITORS/DIRECTORS: For more information, contact Dr. Marshall at (662) 325-8722 or Douglas Marshall.