Monday, May 15, 2017

Nacho Cheese Sauce Probable Source of Gas Station Botulism Cases

Public Health officials in CA believe the source of the botulism cases that occurred from eating at a gas station to be the nacho cheese sauce product.  Most cheese sauce products are made to be shelf-stable for distribution, but once opened, most products may need to be stored at the proper temperatures (outside of the temperature danger zone) to prevent growth. Much of this depends on the formulation (pH, Aw, preservatives).  They also have to be protected against cross contamination.

It difficult to tell whether these product were not properly formulated or were improperly held,  One could guess that the cheese sauce was not properly stored or handled after opening, allowing for a small amount of contamination to grow.  It may have been transferred from a pouch to a canister or serving trey.  For Clostridium botulinun, intoxication to occur, the organism would need to grow in number to produce sufficient toxin.  The product itself would need to be formulated to allow growth and that product would also need to be held at improper temperatures, most likely in the upper part of the temperature danger zone (70F to 125F).

With a thick product like this, people may assume it is like ketchup or mustard that can be left at room temperature after opening....not unless it was formulated that way.  Generally cheese sauce have a higher pH and Aw.   Another potential issue can occur if these products are modified in any way.  Adding peppers or other raw ingredients can be an issue.  Adding water to the product can also be an issue....such as might be the case if the product thickened up after sitting on the hot bar all day.

Sacramento Bee
Nacho cheese to blame for rare botulism outbreak at Sacramento area gas station
By Sammy Caiola
May 10, 2017

Nacho cheese sauce is the likely culprit in a botulism outbreak that has sickened at least five people who visited a Walnut Grove gas station.

On Wednesday, Sacramento County Public Health officials pinpointed the source of the botulism outbreak as “prepared food, particularly nacho cheese sauce” from Valley Oak Food and Fuel gas station in the Delta. Five people are hospitalized in serious condition with botulism, a rare but serious paralytic illness caused by a nerve toxin, and an additional patient is suspected of having the illness.

People who ate prepared food, especially nacho cheese sauce, from the station between April 23 and May 5 and report symptoms should contact their medical provider immediately, the health department said.

The gas station, which sits on a busy stretch of River Road across from the Walnut Grove Bridge, stopped selling food and drink products on May 5 after the county Department of Environmental Management temporarily revoked its permit. Employees of the gas station refused to comment this week on the suspected outbreak.

Botulism symptoms include trouble breathing, blurry vision, slurred speech and droopy eyelids. Hospitals treat botulism with an antitoxin followed by intravenous liquids and breathing support, she said. About 5 to 10 percent of botulism cases are fatal, according to the World Health Organization.

Clostridium botulinum, the bacteria that leads to botulism, thrives in moist, low-oxygen, low-acidity environments, such as in homemade canned foods or cooked commercial foods stored at the wrong temperature, said Linda Harris, a food safety microbiologist at UC Davis. The bacteria is heat-resistant, so it won’t die during the cooking process like other harmful organisms.

The U.S. saw 161 confirmed cases of botulism in 2014, only 15 of which were food-borne, according to the most recent report from the U.S. Centers for Disease Control and Prevention. Most of the other cases were among infants who ingested clostridium botulinum spores before their digestive systems were fully formed.

The California Department of Public Health is investigating two cases of botulism in Orange County this week, both of which are linked to a deer-antler tea product. Other recent food-borne botulism outbreaks involved pesto from a San Clemente farm in 2014 and home-canned potatoes served at an Ohio church potluck in 2015.

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