Prevent contamination as produce grows, say scientists
and vegetables is to intervene while they grow, say US scientists.
The research could help processors apply pressure on farmers to improve the safety of produce before harvesting. A proactive approach in preventing pathogen contamination could develop, with more focus on the producer rather than processor. Researchers from the US Department of Agriculture's Agricultural Research Service (ARS) found that most contamination of produce occurs while it grows. Jeri Barak, research microbiologist with the ARS, found that pathogens like salmonella use specific genes to colonze produce, creating an active interaction with the surface. "When this happens, the bacteria become almost inseparable from the vegetable," she said. The findings may go some way to exonerating processors for pathogen outbreaks of the past, but new methods will have to be developed to decontaminate food effectively. The findings could also impact the use of recycled water to irrigate fields. In September 2006, three people died and more than 200 people fell ill after eating spinach contaminated with E.coli, which investigators traced to back Californian spinach irrigated with recycled water contaminated with feces. That resulted in the FDA stating that washing spinach was an insufficient process of sanitation because the pathogen is systemic and absorbed through the roots. Later in 2006, another outbreak involving lettuce contaminated with E. coli was blamed for infecting at least 48 Taco Bell customers in five states. In the US an estimated 76 million cases of foodborne illnesses occur each year, causing about 325,000 hospitalizations and 5,000 deaths, according to the Center for Disease Control and Prevention (CDC) statistics for 2005. Since 1990, over 400 produce-related outbreaks have occurred across North America. According to 2006 statistics reported to through the CDC by the Foodborne Diseases Active Surveillance Network (also known as FoodNet), some pathogen-related illnesses are on the increase. FoodNet collects data from 10 US states regarding diseases caused by enteric pathogens transmitted commonly through food. The CDC identified 17,252 laboratory-confirmed cases of food poisoning in 2006, including 6,655 cases of salmonella and 590 cases of E.coli O157. In 2005, 16,614 cases were identified, rising from 15,806 in 2004. However, camplylobacter, listeria, shigella and yersinia showed a sustained decline in incidence compared to 1996-1998, although the CDC said that most of the present decrease was due to falls experienced between 1999 and 2002. Barak and other American Phytopathological Society (APS) members will present their latest food safety research and describe future research needs at a symposium titled "Cross Domain: Emerging Threats to Plants, Humans, and Our Food Supply" on July 30. Experts from across the US will discuss the environmental biology of bacteria in fresh produce and the link between plants and bacteria associated with human infections.
