Yet another E. coli outbreak in a petting farm has put four children in hospital and sickened many more. I was at a fake farm recently with the kids and it never ceases to amaze me at how many people don’t seem to realise COW SHIT ISN’T A FOODSTUFF. I watched people let their kids pet the animals and then immediately hand them sweets to eat.

As a microbiologist I am remarkably relaxed about Our Microbial Overlords and their ubiquity but there are some things that piss me off. Like raw milk. And people who expose their kids to risk because their Dunning-Kruger bias makes them think that all the posters saying “WASH YOUR BLOODY HANDS AFTER TOUCHING THE ANIMALS. THEY’RE COVERED IN SHIT, FFS” don’t apply to them or their offspring.

Yes, animals can be cute (excluding the Fluffy Vermin, obviously). Especially lambs when they’re still baguette-sized. But would you stick your tongue up their Chocolate Starfish? Would you let your children? Because that’s what you’re doing when they pet farm animals then stick those dirty digits in their mouths, up their noses and everywhere else. Again, I am the least squeamish person ever when it come to Our Microbial Overlords but there are limits.

And don’t conflate this with the Hygiene Hypothesis – the idea that our kids are generally sicker because they don’t get exposed to enough bugs. (I’ve just written a magazine column on that which I’ll expand on in a future post). There’s bugs and there’s bugs.

Killer Lambs…

Yes, they’re cute but if you’re pregnant the same organisms that cause abortion in ewes can cause women to miscarry. The most common causes of enzootic abortion in sheep are Chlamydia, Vibrio, Campylobacter and Toxoplasmosis. (Brucella abortus is cattle).

There’s also Orf (contagious pustular dermatitis) caused by a virus in the pox family that causes painful sores on the hands, arms, and face – about a quarter of UK sheep farm employees have it – and ringworm (also called club lamb fungus). Expect a red, thickened rash which can lead to disfiguring scars. Rarer are Q Fever (Coxiella burnetti) and Brucella melitensis, a fluke called Fasciola and Echinococcus tape worms. Other organisms associated with lambs, goats and sheep include anthrax, Cryptosporidium, Giardia, Erysipelothrix, Leptospira, Yersinia, tularemia, Rocky Mountain Spotted Fever and West Nile.

E. coli  Basics

Escherichia coli is a common commensal (one of Our Microbial Overlords that lives on / in us) and is mostly harmless. But the few pathogenic strains of it can be very nasty and potentially fatal. It’s rife in farm animal poop and has a REALLY low infectious dose. Between 10 and 100 organisms of E. coli O157 are sufficient to cause infection compared to over 1,000,000 required for other pathogenic E. coli strains.

It’s not just the nausea, diarrhoea (often bloody) and severe abdominal cramps you need to worry about, it can lead to haemolytic uraemic syndrome (HUS) and death. It has a 5 – 10% mortality rate in children under 5 years of age. Generally it’s meat processing establishments that need to be especially vigilant as ground beef is a principal route of transmission – grinding together meat from many different cows (and the occasional horse) spreads it throughout a batch. It can also be found in unpasteurised (raw) milk or apple cider, or cheeses made from raw milk if the cheese maker doesn’t understand pH. Vegetables that come in contact with animal faeces can also be tainted with E. coli, as with the 2006 spinach outbreak.

The harmful strains are generally Shiga toxin-producing E. coli (STEC), the most common of which is E. coli O157:H7. These toxins are heat-stable and so are not denatured by cooking. The toxin is heat-stable up 100°C. Other recent outbreaks in the UK include one associated with a children’s farm in Surrey (ungulates – most notably cattle but also deer, elk, goats and sheep are known carriers) as well as outbreaks associated with poor hygiene such as recent one in Glasgow). About a thousand cases a year are serious enough to be reported to the HPA.


There’s a big section on E. coli in the FAQ section. Outbreaks like this can destroy a business – but, more importantly, can make kids STS (Sicker Than Shit) in a heartbeat.

And if anyone tells you they grew up on a farm / bathed in cow shit / know someone who ate lamb once and they’re fine just remember the plural of anecdote is anecdotes, not data. And punch them – in the interests of public health, of course.