Conditions EHEC infections

EHEC is short for enterohemorrhagic Escherichia coli. This is a highly pathogenic (disease-causing) group of bacteria.

Some strains of Escherichia coli are normal inhabitants of the human intestine. EHEC bacteria, however, occur naturally in the digestive tract of ruminants such as cows, sheep or deer. EHEC bacteria are capable of producing toxins that can cause severe illness in human beings.

EHEC infections can go unnoticed but may also be accompanied by severe diarrhea. One potential but rare complication is hemolytic uremic syndrome (HUS). This can sometimes cause acute kidney failure, among other things. HUS is normally only temporary and usually abates later. Late complications may sometimes occur.

An EHEC infection may cause no symptoms at all, but it can also be very severe and lead to complications.

Initial symptoms usually appear 2 to 10 days after infection. Most conditions are characterized by watery diarrhea with nausea, vomiting, abdominal pain and in rare cases fever.

Severe cases

In 10 to 20 out of 100 people affected, the watery diarrhea becomes bloody diarrhea with cramping abdominal pain and sometimes fever. Babies, small children, older people and people with immune deficiency are particularly affected.

Cases with complications

Around 5 to 10 out of 100 people with symptoms develop hemolytic uremic syndrome (HUS) 5 to 12 days after the first bouts of diarrhea. Children are particularly affected. HUS causes destruction of red blood cells and rapid deterioration of kidney function. This causes a buildup of toxic metabolic products in the blood. The platelets are also destroyed, which impairs blood clotting.

EHEC infections are caused by infection with enterohemorrhagic Escherichia coli (EHEC) bacteria. The word “enterohemorrhagic” indicates that the severe inflammation of the digestive tract causes bloody diarrhea.

EHEC is a type of bacteria that produces certain toxins. These toxins are called Shiga or Vero toxins.

EHEC bacteria occur naturally in the digestive tract of ruminants such as cows, goats, sheep or deer. These animals shed the bacteria in their feces.

Human beings become infected with EHEC when they come into contact with the feces of these animals and the bacteria enter the mouth, for example, via the hands. 

Indirect infections are also possible, for example by touching objects contaminated with EHEC bacteria. This can also happen when stroking the fur of ruminants. Ruminants do not become ill if they have EHEC bacteria in their digestive tract. So even healthy animals may also be infectious. 

Common sources of infection are also contaminated water, such as from a bathing lake, as well as drinking or processing unpasteurized milk, eating raw sausages or meat that has not been cooked through. People may also pick up infections from green leafy vegetables, such as lettuce, spinach or sprouts. A very small number of these bacteria is sufficient to cause an infection.

People who have the infection can also pass it on easily, particularly to others living in the same household. EHEC bacteria are highly infectious and can be excreted with feces for days or weeks, even after the symptoms have cleared up. In children, the shedding of EHEC bacteria generally lasts longer than in adults. Even if no symptoms are present, the pathogens can be continue to be shed in the stool for more than a month. However the risk of infection falls sharply over time.

EHEC bacterial infections occur all over the world. The exact number of EHEC cases cannot be determined because not all cases of diarrhoeal illness are tested for the triggering pathogens. People with no symptoms are also not routinely examined.

3,442 cases of EHEC infections were reported in Germany in 2023. Children under 5 years of age, particularly one-year-olds, are most frequently affected. There were 5 deaths caused by EHEC in the context of hemolytic uremic syndrome (HUS). These occurred in the older population.

EHEC infections range from mild to extremely severe. However, even severe, bloody diarrhea during an EHEC infection can resolve without long-term consequences. Even a complicated form involving hemolytic uremic syndrome (HUS) can usually be treated effectively. However, late complications are a possibility after HUS.

Complicated course of HUS

If the toxins produced by EHEC bacteria spread beyond the intestine to other parts of the body, HUS can develop. The toxins particularly attack the walls of small blood vessels that are found all around the body. HUS is therefore a condition that can affect multiple organs at the same time.

Typically, the disease causes symptoms first and most severely in the kidneys and the gastrointestinal tract. However, it can also affect the brain and the nerves, the pancreas and the skeletal and cardiac muscles.

This can sometimes lead to neurological problems or pancreatic diseases such as diabetes mellitus with insulin deficiency. The classic distinction between type 1 diabetes and type 2 diabetes is not possible here. 

Children who have recovered from hemolytic uremic syndrome are more susceptible to kidney diseases afterwards. The kidney damage can also cause hight blood pressure. It is rare for HUS to cause permanent kidney damage. In such cases, the children may require artificial blood purification – dialysis.

EHEC bacteria are relatively stable and can survive in the environment for a long time. Just a small amount of bacteria is enough to cause the condition. 

The following rules on hygiene help to prevent infection:

• regular handwashing with soap after going to the toilet, before eating and before preparing meals
• thorough cleaning of hands after contact with animals in a petting zoo or farm: for small children in particular, before they put their fingers in their mouth or eat something
• follow kitchen and food hygiene rules closely
• if possible, avoiding close contact with people who are ill. This is particularly the case for siblings.

Special rules apply to those who are infected and their contacts:

• You should, if possible, use a separate toilet. Hygiene is particularly important when going to the toilet.
• Hands should be washed thoroughly after changing diapers of infected children.
• People affected and those who are from the same household are not permitted to enter community facilities such as kindergartens or schools. Doctors providing treatment must decide when they can return to visit or work in a community facility.
• People who prepare and process food or work in the kitchen of a community facility must not go to work until they have stopped excreting the EHEC pathogens in their stool.

For more information on preventing EHEC infections, see the consumer tips provided by the Federal Institute for Risk Assessment (BfR).

Any diarrheal disease can be caused by EHEC bacteria.

However there are certain indications that prompt doctors to determine the pathogen more precisely, for instance where:

• children under 6 with diarrhea require hospital treatment
• the diarrhea is bloody, or a colonoscopy reveals a bloody inflammation of the mucosa lining of the digestive tract
• diarrhea occurs in people who process foods or work in kitchens or canteens
• hemolytic uremic syndrome (HUS) is present
• people have had contact with people with HUS
• children have acute kidney failure

In these cases a stool sample is sent to the laboratory to be tested for EHEC and the toxins produced by EHEC. In the case of HUS, a blood sample should also be tested for certain antibodies.

Treatment of an EHEC infection is generally restricted to supporting vital bodily functions. The most important factors are ensuring sufficient mineral and fluid intake. Intravenous fluid replacement can reduce kidney damage if applied at an early stage. This infusion therapy can only be provided in a hospital.

Where complications such as hemolytic uremic syndrome (HUS) occur, doctors will start by administering medication to stimulate excretion of fluid via the kidneys. If the kidneys have already stopped functioning, artificial blood purification (dialysis) may be necessary. Patients may sometimes also need blood transfusions to replace red blood cells, platelets or plasma.

The infektionsschutz.de website provides more information about EHEC.