Girl in Hamburg dies of EHEC infection

Hamburg elementary school student died of EHEC infection

20.02.2012

In the past year, the EHEC epidemic has shockingly demonstrated to people in Germany just how far-reaching the effects of food contamination can be with enterohaemorrhagic Escherichia coli (EHEC) bacteria. However, since the cause of the EHEC infections was detected and the spread stopped, in recent months it has become quite quiet around the dangerous intestinal bacteria.

Now, the death of a little girl in Hamburg causes renewed concern. The six-year-old girl died as a result of EHEC infection. Whether the triggers of the EHEC epidemic last year, the novel particularly dangerous EHEC pathogens (HUSEC 41) of the serotype O104: H4, are also responsible for the death of the primary school student, is not yet known. But the concern in the population is growing. The parents are alarmed and, for fear of a return of the intestinal epidemic, are currently paying particular attention to possible EHEC symptoms in their children.

Search for the source of infection
The six-year-old from the Hamburg district of Blankenese had died in the night of Sunday as a result of an EHEC infection. However, it is still unclear which variant of the pathogen has caused the disease of the girl. Whether the particularly aggressive EHEC pathogen HUSEC 41, which had triggered the epidemic with more than 4,000 diseases and over 50 deaths last year, is behind the girl's infection, can not be confirmed so far according to the Hamburg Health Department. Also, it has not yet been clarified on which way the primary schoolgirl could have been infected, according to the communication from the health authority. In the environment of the primary schoolgirl, there were no further infections, said a spokesman for the health department. In order to track down the pathogens, samples were taken of the food the girl had eaten. „We hope that there will be results during the day“, emphasized the speaker of the Hamburg health authority. All that is certain at the moment is that the consequences of an EHEC infection have caused the girl's death. The six-year-old woman apparently suffered from the so-called hemolytic uremic syndrome (HUS), which can be observed in particularly severe disease progression of EHEC infections. HUS is caused by the toxins of the EHEC pathogens, which can destroy the blood vessels and cause tissue bleeding. In the pathogen strain HUSEC 41, a large number of EHEC patients also suffered from hemolytic uremic syndrome last year.

Around 1,000 EHEC infections annually in Germany
In general, EHEC infections are not uncommon, as the pathogens in the intestine of ruminants such as sheep, goats and cattle can reproduce relatively well and keep long term. On the excretions of the animals, the pathogens sometimes reach foods such as raw vegetables or fresh salad. In addition, sprouts are particularly endangered, as the spread of EHEC pathogens by sprouts from Egyptian fenugreek seeds in the early summer of last year showed. Every year, around 1,000 people develop EHEC infection in Germany, even without a major epidemic. Normally, only about 60 of them contract HUS. In the aggressive EHEC pathogen strain that triggered the wave of infection last year, however, a significantly larger proportion of EHEC patients suffered hemolytic uremic syndrome.

Dangerous toxin of EHEC pathogens
The EHEC pathogens may be particularly dangerous to humans because of two particular characteristics. First, the pathogens can settle in the intestine and multiply, second, they release the so-called Shigan toxin, which causes the destruction of the blood vessels when they die off. The toxin is transported with the red blood cells and destroys the endothelial cells (inner wall layer of the lymphatic and blood vessels) on reaching the renal vessels. If the protective barrier of the endothelial cells is destroyed, the poison can penetrate into the cells and cause their death. The venom of the EHEC pathogen docks to certain receptors in the cells, thereby blocking the protein synthesis required for cell survival. However, by implementing proteins in the cells, the EHEC agents can not only cause cell death but also facilitate the fixation of bacteria in the intestinal tissue.

EHEC infection usually survived after a maximum of ten days
Although the EHEC poison in the human body triggers a whole series of dangerous processes, a healthy organism can generally cope with the strain. Thus, the infection in 80 to 90 percent of those affected with symptoms such as convulsive abdominal pain, severe diarrhea, nausea and vomiting, which occur after three to four days incubation period. After ten days, the EHEC infection in individuals with intact immune defense is usually over. However, although the sufferers have no symptoms, they can still transmit over several weeks EHEC pathogens. Like the microbiologist from the University Hospital Heidelberg, Klaus Heeg, opposite the news magazine „Focus“ explained, this is „because the bacterium itself does not make you sick, but the toxins - and they become inactive over time.“ Nevertheless, the EHEC pathogens are still present in the organism, even if the body has brought these under control and the acute infection is over.

More serious consequences of EHEC infection
However, for ten to twenty percent of patients, EHEC infection is not over after this first period of suffering. Around one week after the first symptoms, they develop a so-called enterohaemorrhagic colitis (EHEC-related intestinal inflammation) and at worst the hemolytic uremic syndrome. Typical feature of the intestinal inflammation is a very watery diarrhea with blood in the stool. Since the EHEC pathogens have increasingly spread in the intestinal tissue, the organism can no longer keep them weak and the toxins show their fatal effect. About 50 percent of those affected suffer from hemolytic uremic syndrome in the further course of the disease. The typical features of HUS are increased endothelial damage, which causes internal bleeding, especially in the area of ​​the renal arteries. As a result, many patients suffer from so-called anemia (anemia), which in turn causes a deficient oxygen supply to the whole body. This deficiency of oxygen can be manifested by numerous symptoms such as a massive decline in performance, fatigue, headache, impaired consciousness, tinnitus, nausea, difficulty concentrating, insomnia and blurred vision. In severe cases, the renal damage in the course of hemolytic uremic syndrome can also cause an acute renal failure that is life-threatening for those affected. Around two percent of HUS patients do not survive the disease.

Acute renal failure due to hemolytic uremic syndrome
Acute kidney failure in the course of HUS is one of the most serious consequences of EHEC infection. Renal failure causes regulatory problems in the fluid, electrolyte and acid-base balance, which can interfere with urinary excretion. Since the end products of the protein metabolism and other urinary substances remain in the organism, life-threatening urea poisoning or uraemia (urinary substances in the blood) is imminent. These poisonings of the body can, in the worst case, cause a multi-organ failure, which may result in the death of the patient. In addition, HUS can cause lasting damage to the kidneys. For some patients, a kidney transplant is the last hope or they are time dependent on dialysis (blood purification).

EHEC therapy limited to treatment of symptoms
The treatment of EHEC infection is usually limited to treating the symptoms. The direct control of EHEC bacteria with the help of antibiotics is out of the question, as the pathogens release the Shigan toxin in their destruction and can aggravate the complaints of patients to life-threatening symptoms of intoxication. Thus, in the case of severe EHEC infections, only the administration of infusions to compensate for the loss of fluid and salt, as well as the blood purification to remove disease trigger and toxins from the body. Dialysis is a must for HUS patients with advanced kidney disease as it is the only option to reduce the incidence of urinary substances in the blood. (Fp)

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Picture: Markus Wegner