If you read this newspaper or follow other forms of media, you’d have doubtless heard of the E. coli outbreak in Europe that has been dominating headlines for the past few weeks. What is it all about and why does it matter?
What is E. coli?
At its simplest, E. coli is a bacterium. Some of you may be surprised to hear that not all E. coli strains of bacteria are deadly dangerous. In fact, E. coli is one of the longterm tenants in that gaseous food depot known as our bowels. Yes, E. coli lives in our bowels and has been there from soon after we were born.
So should we be terrified at the thought of E. coli sitting in our bowels from our infancy?
Not at all. In fact, the E. coli in our bowels is part of the bacterial flora that has been helping us in many ways - for example, in digesting food. It also prevents more dangerous bacteria that live in our bowels, such as Clostridium difficile, from being able to multiply and reach sufficient numbers to cause us harm.
So the E. coli living in our bowels normally is completely harmless?
It is harmless as long as it remains inside our bowel. But if it gets into other parts of the body, then our own E. coli can cause problems. The most common infection we see with our own E. coli is a urine infection.
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| File picture shows bean and salad sprouts in Berlin June 6. New data has confirmed that bean sprouts are the most likely source of the deadly E.coli outbreak in Germany, German health authorities said. REUTERS |
This occurs when the E. coli in our bowel jumps across to the bladder. Given that the openings to the bowel and the bladder are pretty close to each other (I’m not going to draw a picture - just use your imagination), it doesn’t have to travel far. While an isolated bladder infection doesn’t make you too sick, it is a different matter if the E. coli can jump from the bladder into the bloodstream. This is called Gram negative septicaemia and guarantees you a few days in hospital, probably in an Intensive Care Unit.
But what’s going on in Europe with E. coli?
E. coli can also cause food poisoning. When this happens, it isn’t our E. coli that is responsible - it’s E. coli from outside sources that is at fault. Yes, there are different types of E. coli. Please don’t be surprised. Would you be shocked if I said that not all Sri Lankans look alike? Of course not. Similarly, we shouldn’t assume that all E. coli strains are the same - you’d be guilty of bacterial racism if you did so! They all have their differences relating to their invasiveness, their antibiotic resistance patterns and the toxins they produce. The E. coli in the European outbreak produces a toxin that is responsible for the severe and even fatal sicknesses in victims, namely haemorrhagic colitis and HUS.
So what are HUS and haemorrhagic colitis?
Haemorrhagic colitis refers to inflammation of the large bowel that often causes bloody diarrhoea which is usually accompanied by abdominal pain and fever. If severe enough, people with haemorrhagic colitis can become dehydrated, perforate their bowels, suffer serious bleeding or die. HUS stands for haemolytic uraemic syndrome. HUS is a potentially deadly syndrome that can cause low platelet counts, anaemia by breaking apart red blood cells and severe kidney failure. Sometimes, the kidney failure is so severe that it requires dialysis.
Where did this E. coli strain in Europe come from?
Like us, food animals harbour E. coli in their bowels. So not surprisingly, outbreaks of HUS in the past have often been attributed to the consumption of undercooked meat. But in this current outbreak, vegetables have been implicated with the WHO website warning that bean and seed sprouts are the likely culprits at the moment. How do vegetables get E. coli in them from an animal’s bowel? It doesn’t make sense at first.
But if you think about it, there are a few possibilities. For example, the farm animals might be living right next to the vegetables; therefore, cross-contamination of the raw vegetables by animal faeces could occur. Alternatively, manure containing the E. coli strain might be used to provide nutrients to the vegetables.
Even the water used to irrigate crops and vegetables could have become contaminated with animal sewage. But sometimes we don’t find the food source of such outbreaks and even when we do, authorities are unable to work out how the contamination occurred.
Has this been a serious
outbreak?
As far as E. coli outbreaks go, this has certainly been serious. The World Health Organisation reported that as of June 11, sixteen countries over two continents had had cases of E. coli haemorrhagic colitis or HUS. Nearly all cases had been linked to Germany. There’d been 812 cases of HUS with 23 deaths and around 2443 cases of haemorrhagic colitis with 12 deaths - death rates of 3% and 0.5% respectively. Apart from the human casualties, don’t forget the economic and political cost of a deadly food outbreak.
Contaminated food has implications for those people trying to export the product overseas.
This is especially so early in the outbreak when the contaminated food product isn’t known. Importing countries at that stage are reluctant to accept any food product from that country. Similarly, tourists may defer their visit to that country until the outbreak has ended. Those tourists already there during the outbreak will almost certainly curtail their dietary habits. All of these factors impact on that country’s economy. Diplomatic rows can also occur over foodborne outbreaks. For example, Spain is allegedly upset with seemingly incorrect accusations early on in the outbreak that Spanish produce were to blame - the so-called “killer cucumbers”.
So that’s E. coli, haemorrhagic colitis and HUS in a nutshell. It’s a fascinating depiction of the interplay between agriculture, infectious diseases and politics - but one the world can definitely do without!
(Sanjaya Senanayake is an Associate Professor of Medicine at the Australian National University and a Senior Specialist in Infectious Diseases) |
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