Plant pathologists are questioning the validity of food recalls, stressing that prevention must be the best tool to reducing food intoxication.
"When an outbreak occurs, most of the infected produce has already been consumed," said Steve Scheuerell, faculty research associate at Oregon State University's Department of Botany and Plant Pathology. "Usually recalls will not help. This is why prevention is key to keeping food safe," he added.
Recent trends in global food production, processing, distribution and preparation are creating an increasing demand for food safety research in order to ensure a safer global food supply. Food and waterborne diarrhoeal diseases are leading causes of illness and death in less developed countries, killing approximately 2.2 million people annually according to the World Health Organisation, most of whom are children.
Recent advances in food safety research are enabling plant pathologists to gain insight into how dangerous human pathogens, such as strains of E.coli and Salmonella, can survive on fresh fruits and vegetables and what can be done to control future outbreaks.
In order to cut the potential for the transfer of pathogens to fresh produce, plant pathologists are stressing the need to implement and maintain sanitary growing and harvesting conditions worldwide.
"As the US increases its importation of produce, it is increasingly important to us that growers everywhere have good quality irrigation water and sanitary conditions for their workers," commented Scheuerell.
Using techniques developed by plant pathologists, scientists are just beginning to understand how human pathogens colonise leaf surfaces, and how their survival can be influenced by manipulating leaf surface microflora and environmental conditions, added the scientist.
Earlier this month a cluster of Salmonella Enteritidis (SE) cases - marked by a distinctive pulsed-field gel electrophoresis (PFGE) pattern - were identified in the US and traced back to the consumption of natural raw almonds. The almonds, from Paramount Farms, California, were sold across the US under several brands and exported to China, Taiwan, Democratic Republic of Korea, France, Italy, Japan, Malaysia, Mexico and the UK.
Other foodborne pathogens are emerging because they are new microorganisms or because the role of food in their transmission has been recognised only recently. Infection with Escherichia coli serotype O157:H7 (E. coli) was first described in 1982. Subsequently, it has emerged rapidly as a major cause of bloody diarrhoea and acute renal failure. The infection is sometimes fatal, particularly in children.
Outbreaks of infection, generally associated with beef, have been reported in Australia, Canada, Japan, United States, in various European countries, and in southern Africa. Outbreaks have also implicated alfalfa sprouts, unpasteurised fruit juice, lettuce, game meat and cheese curd.
In 1996, an outbreak of Escherichia coli O157:H7 in Japan affected over 6,300 school children and resulted in two deaths. WHO claims that this is the largest outbreak ever recorded for this pathogen.
At an upcoming conference in Anaheim, California plant pathologists will present more on food safety and fresh produce during the 'Food Safety as Influenced by Phyllosphere Microflora' symposium at the American Phytopathological Society annual meeting from July 31 - August 4, 2004.