Nearly 1 out of every 25 restaurant-associated foodborne outbreaks with identified food sources between 1998 and 2008 can be traced back to contaminated salsa or guacamole, more than double the rate during the previous decade, according to research released by the Centers for Disease Control and Prevention today at the International Conference on Emerging Infectious Diseases.
"Fresh salsa and guacamole, especially those served in retail food establishments, may be important vehicles of foodborne infection," says Magdalena Kendall, an Oak Ridge Institute for Science and Education (ORISE) researcher who collaborated on the CDC study. "Salsa and guacamole often contain diced raw produce including hot peppers, tomatoes and cilantro, each of which has been implicated in past outbreaks."
To better assess the role of these popular foods in outbreaks, Kendall and her colleagues searched all foodborne outbreaks reported to the CDC for those with salsa, guacamole or pico de gallo as a confirmed or suspected food vehicle and analyzed trends in the proportion of all outbreaks with identified food sources.
CDC began conducting surveillance for foodborne disease outbreaks began in 1973, yet no salsa- or guacamole-associated (SGA) outbreaks were reported before 1984. Restaurants and delis were the settings for 84 percent of the 136 SGA outbreaks. SGA outbreaks accounted for 1.5 percent of all food establishment outbreaks from 1984 to 1997. This figure more than doubled to 3.9 percent during the ten-year period from 1998 to 2008.
Inappropriate storage times or temperatures were reported in 30 percent of the SGA outbreaks in restaurants or delis and may have contributed to the outbreaks. Food workers were reported as the source of contamination in 20 percent of the restaurant outbreaks.
"Possible reasons salsa and guacamole can pose a risk for foodborne illness is that they may not be refrigerated appropriately and are often made in large batches so even a small amount of contamination can affect many customers," Kendall says. "Awareness that salsa and guacamole can transmit foodborne illness, particularly in restaurants, is key to preventing future outbreaks."
Risk can be lowered by following guidelines for safe preparation and storage of fresh salsa and guacamole to reduce contamination or pathogen growth.
"We want restaurants and anyone preparing fresh salsa and guacamole at home to be aware that these foods containing raw ingredients should be carefully prepared and refrigerated to help prevent illness," says Kendall.
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