Well, let's get to the point.
EHEC - Enterohaemorrhagic Escherichia coli
You'll probably have heard of this before. Bloody E. coli. The pathogenic version which makes your intestines dump it's contents in fluid form, often mixed with blood. In 2011, it struck in Germany, claiming the lives of over 50 people, and turning over 4000 people into a shivering, ill wreck of a being. Why the hell is it this dangerous anyways?
What the hell is it anyway?
Escherichia coli is a bacteria most commonly found in the intestines of warm-blooded animals (this includes humans). Unlike the E. coli variants found in our own body, EHEC is a variant of E. coli capable of causing illness.
Common names are STEC (Shiga-Toxin producing E. coli) and VTEC (Vero-Toxin producing E. coli)
What does it cause?
The majority of the people suffering from an EHEC-infection have an elevated body temperature, throw up, have stomach cramps and diarrhea. Some people don't even show symptoms.
In bad cases, Haemorrhagic Colitis (HC) occurs. Colitis is the inflammation of the intestines, and in HC, the capillaries start leaking blood. This results in bloody diarrhea and sudden stomach cramps. HC can advance to Hemolytic Uremic Syndrome (HUS), in which the kidneys start failing. The patients starts urinating less, until the urine output is completely halted. They also suffer from anemia because of the leaking of blood.
?! How the hell does it work?!
As soon as the E. coli bacteria ends up in the intestines, it settles down in your intestines and reproduces itself. This in itself can damage the lining of your intestines, resulting in bleeding and inflammation.
EHEC then produces Shiga-like toxins (Stx 1 and Stx 2) which can cause HC and HUS. Because the intestines are already damaged, the toxins can enter the bloodstream.
Shiga-like toxins are composed of two parts, called A and B (I know, they're soo original..)
When the toxins bind to the receptors of a cell (Gb3 receptors, in this case), the cell allows them to enter it, and the A-part is split into two pieces. One of the A-pieces then halts the production of proteins by taking away an important piece of the ribosome (a structure which is responsible for producing proteins).
Taking down protein synthesis doesn't result in immediate cell death, but the cell can time-bomb itself and destroy itself in a process called "Apoptosis".
The cells in the kidneys are believed to express a lot of those Gb3 receptors, making them extra vulnerable to attacks. Especially the capillaries are said to have a lot of Gb3 receptors, as they're the first to be brought down by the toxins. Aside from this, the red blood cells start binding themselves to the blood vessels, narrowing them and making it harder for other red blood cells to pass. Eventually, a lot of red blood cells attempting to squeeze themselves through the vessels are damaged, resulting in anemia.
The kidneys require a lot of blood to function well, and when not enough blood reaches the kidneys, they'll suffer damage. If the kidneys fail, the patients will need dialysis, a process in which a machine filters the blood.
Treatment
Most of the patients don't need to be hospitalized. Taking plenty of rest and fluids is enough. Taking antibiotics would be a bad idea, as they stimulate the release of toxins.
For people with HC, hospitalization would be a brilliant idea, as HC can easily transform into HUS.
For patients with severe HUS, a kidney transplantation may be necessary.
Sources of EHEC
Alright, enough of the scary crap.
EHEC is commonly found in the intestines of herbivores, mainly ruminants such as sheep and cows.
These animals generally don't show signs of sickness, as their intestines lack Gb3 receptors.
EHEC can be found on the outside of the meat, or in the case of ground beef/hamburgers, also on the inside. This is why we Dutchies call EHEC "Hamburger-disease".
Aside from meat products, veggies and fruits can also carry the bacteria.
Unpasteurized milk can also transmit the disease (here's one for all of you unprocessed-food-junkies!).
And, crap from animals, and humans.
Prevention
Bad hygiene is the no. 1 cause. 'Nuff said.
During slaughter, the contents of the intestines must NOT come in contact with the meat.
The meat of these animals must be cooked thoroughly, especially if its ground meat.
Unpasteurized milk sucks, but you already know this. Right..? RIGHT?!
Washing hands prior to eating food and after going to the bathroom is a must, as your crap can contain pathogens.
When you're visiting petting farms and zoos etc. wearing boots is recommended, and washing your hands after touching the animals is also a must.
If you're going swimming in a pool in which animals could take a dump, make sure you don't accidentally swallow the water.
That's about it.
Quynh
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