E. coli strikes America (again)

Hugh Pennington

Romaine lettuce in the US is currently under the cosh of a Food Safety Alert: don’t eat it, whether head or heart or baby; don’t sell it; and don’t eat ready-mixed Caesar salad, which contains it. Contamination with E. coli O157:H7 is the reason. An outbreak started in October, with 50 cases across 11 states, as well as in Ontario and Quebec, with 13 in the US admitted to hospital. The lettuce may have been grown in California, unlike the produce that caused the first romaine outbreak this year, which was grown in Yuma, Arizona. That outbreak lasted from March to June, and was the biggest E. coli O157:H7 outbreak in the US for many years, with 201 cases (96 hospitalised) and five deaths.

Working out exactly how the E. coli got onto the lettuce is proving to be very difficult. The only certainty is that it has come from the bowels of ruminant animals, such as cattle. For the beasts it is harmless. But for humans it is the nastiest of all food poisoning bacteria. The lucky victims just get bloody diarrhoea. But in a minority the kidneys fail, usually reversibly, but not always. A few get brain damage, and some die from cardiac complications. It is a challenge for physicians because once an infection has started, nothing can be done to prevent these complications. Antibiotics probably make things worse. And it is challenging for food safety, because the infectious dose is very low. Eating ten bacteria can set up a life-changing or lethal infection.

E. coli O157:H7 is a relatively new bug. It was first identified as a human pathogen in the early 1980s, when it was seen as mainly a meat problem. In the US it was called the ‘burger bug’. In the UK, bad butchers were the villains. But the first outbreak in Britain, in East Anglia in 1985 (49 cases, one death), had nothing to do with beef. Contaminated vegetables were considered the source.

An important clue was that three quarters of the victims were women. In food poisoning outbreak investigations, such a gender balance points to plants as top suspects. It was the case in the Yuma outbreak. And 68 per cent of victims were women in the enormous fenugreek seed sprout E. coli O104:H4 outbreak in Germany in 2011, caused by a hybrid E. coli that has a toxin gene like that of E. coli O157:H7. It is the toxin that causes the damage. It targets small blood vessels. The bowels, the kidneys and the brain have plenty, explaining the blood in the diarrhoea, the kidney failure and the epileptic fits. Three of the sufferers in the East Anglia outbreak were vegetarians. So being one doesn’t mean that animal products are never directly consumed, even if it is uncooked manure to mouth.

President Trump has promised that for every new regulation, two will go. The FDA has deferred the introduction of new irrigation water-testing rules. My experience is that when food poisoning strikes close to home, deregulators become rulemakers. The Trump family Thanksgiving dinner included Caesar salad. But the White House has said that romaine lettuce was not served. The incubation period of E. coli O157:H7 gastroenteritis can be as long as 12 days. Time will tell.