If you thought that because you do not make a habit of eating avocado skins that you therefore needn’t wash avocados before slicing into them, you are incorrect. I know, I know. Take a minute.
The US Food and Drug Administration released a report last week (Dec. 7) that found Listeria monocytogenes bacteria on more than 17% of the avocados skins it sampled between 2014 and 2016. Roughly 0.2% of the avocados had Listeria living within the meat of the fruit itself.
But dragging a knife through the skin and into the meat could hypothetically drag Listeria along with it. Washing the avocado skins before cutting into them is the best way to avoid contamination.
The FDA adds that in addition to washing literally every piece of produce you intend to eat, regardless of rind, you should “scrub firm produce (which includes avocados) with a clean produce brush, and then dry it with a clean cloth towel or paper towel to further reduce bacteria that may be present.” And you should wash your hands after handling avocados, too.
A person with a Listeria infection might develop a fever, muscle aches, diarrhea, and/or nausea. In severe cases, the infection can spread to the nervous system, causing disorientation, convulsions, and a stiff neck. It typically isn’t a severe threat to a healthy adult, but pregnant women, newborns, older people, and people who have weakened immune systems are particularly vulnerable to even small doses of Listeria. It’s especially dangerous during pregnancy, because a Listeria infection can transfer to the fetus. About 1,600 people get listeriosis each year in the US, and about 260 die from the illness, according to the US Centers for Disease Control.
The FDA also found bacteria from the Salmonella genus on 12 avocado skins in the survey, which amounted to less than 1% of those sampled. “The findings of this assignment affirm that Salmonella may be present on avocados and that Listeria monocytogenes may be present on or in the fruit,” the FDA wrote.
So far, despite all this, a Listeria outbreak from avocados has never been reported in the US. According to the CDC, there were 12 outbreaks of foodborne illness related to avocados from 2005 to 2015—nine from Salmonella and three from E. coli.
Next stop for federal scrutiny? Store-bought guacamole: “The agency is seeking data on the prevalence of Salmonella and Listeria monocytogenes in processed avocado and processed avocado products,” the FDA wrote.