Hi. How high is the risk of an E. coli infection at a pumpkin patch petting zoo for an eight-month-old? Thank you.—Deb
I am enamored of the specificity of this question, and will endeavor to answer specifically.
The concern here is with the petting zoo aspect of this adventure. Pumpkin picking does not pose an E. coli risk. But there have been E. coli cases associated with petting zoos. There was an outbreak in 2019, and over the period from 1996 to 2012, this paper estimates about 3,000 cases in outbreaks in the U.S. and Canada. This includes any cases spread by farm fairs, petting zoos, etc. So it’s a clear upper bound on petting zoo cases.
How many petting zoo visits were there over this period? It’s hard to know! An estimated 180 million visits to all zoo-related locations occur each year in the U.S. If we imagine that, say, 25% of those are to locations with petting-related options, that’s 45 million visits a year. Over the period from 1996 to 2012, that would be 720 million visits. So we’re talking about 3,000 cases over 720 million visits, or a risk of about 1 in 240,000. If you visited a zoo every day, this event would occur about once every 657 years.
Obviously I have made many assumptions here, probably most of which are biased in one direction or another. However: virtually any assumptions that make any sense here are likely to lead to a conclusion of a tiny risk.
It is always a good idea to wash your child’s hands after they touch an animal. Since E. coli spreads through ingestion of poop, careful hand-washing is the key avoidance practice.