On average, one to three days after infection with a bacterial pathogen (including EHEC), the following symptoms appear
- Watery, later bloody diarrhea
- vomiting
- fever
- Abdominal cramps and abdominal colic
The toxins of the bacteria affect not only the gastrointestinal tract but also the cerebral circulation. This can also lead to lethargy, hyperexcitability, seizures or other neurological symptoms.
There are also so-called atypical forms of hemolytic uremic syndrome. These are rare and mostly genetic. Atypical haemolytic uraemic syndrome occurs in episodes that are often triggered by a respiratory or gastrointestinal infection. It generally shows the same symptoms as the bacterial form.
If the presence of haemolytic uraemic syndrome is suspected based on the characteristic symptoms, the diagnosis is confirmed by a blood and urine test. In the event of a disease, the following laboratory parameters can be determined:
- Drop in the red blood pigment (hemoglobin) with anemia
- drop in the survival time of red blood cells (erythrocytes) to less than 100 days (haemolysis)
- Damaged red blood cells (fragmentocytes)
- drop in the concentration of blood platelets (thrombocytopenia)
- Increase in urea and creatinine levels (uremia)
Components of the blood under the microscope: erythrocyte (red blood cell), thrombocyte (platelet), leukocyte (white blood cell)
In addition, a bacterial pathogen is detected in the blood. If this cannot be found, an analysis of the genetic material is considered to confirm the diagnosis of atypical hemolytic uremic syndrome.
There is currently no causal therapy for hemolytic uremic syndrome. Therefore, supportive and, if necessary, intensive medical therapy is usually used.
Treatment of bacterial hemolytic uremic syndrome
As the underlying bacterial infection subsides within 5 to 10 days, no antibiotic treatment should be given in the acute phase (diarrhea phase). Antibiotics are suspected of leading to bacteriolysis (decomposition of the bacteria). This accelerates the release of the disease-causing toxin and thus leads to a worsening of the condition.
Instead, plasmapheresis can be used to reduce the circulating toxin concentration. This involves removing the blood plasma from the body and replacing it with frozen fresh plasma. Treatment with corticosteroids or H1 and H2 blockers is often carried out in advance to prevent an allergic reaction.
In severe cases and unsuccessful plasmapheresis, drug therapy with the antibody eculizumab may be indicated. In some cases, plasmapheresis and eculizumab are also administered as a combination therapy.
The evaluation of HUS cases during the EHEC epidemic in Germany in 2011 showed that a so-called "best supportive care" approach, in which the best possible supportive treatment measures are taken, shows similar results to plasma exchange, at least in the short term. High blood pressure (hypertension) is treated with supportive antihypertensive drugs.
If there is severe anemia due to a shortened red blood cell survival time (hemolytic anemia), red blood cell transfusions are required. If life-threatening bleeding occurs due to the low blood platelet concentration, platelet concentrates are used. If there is renal insufficiency with fluid retention (edema, ascites, anasarca) and heart failure with pulmonary edema, dialysis is necessary.
Treatment of atypical hemolytic uremic syndrome
Atypical hemolytic uremic syndrome is caused, among other things, by gene mutations that negatively interfere with the innate (non-specific) immune response. The exact underlying mechanisms are not fully understood, which is why many of the therapeutic approaches are still being tested in clinical trials.
The treatment of choice is a combination of plasmapheresis and/or plasma infusions and administration of fresh frozen plasma. In certain forms of atypical haemolytic uraemic syndrome, eculizumab, which has an inhibitory effect on the dysregulation of the non-specific response, can lead to an improvement in symptoms.
If the disease is due to a deficiency of a specific protein involved in the innate immune response (so-called complement factor H), a liver transplant may be an option. If end-stage renal failure is also present, a simultaneous kidney transplant is considered.
Immunosuppression (suppression of the immune system) may also be indicated in some forms of atypical hemolytic uremic syndrome.
If the cause of the disease is a substance contained in other medications, these should be discontinued.
The prognosis is generally good for successfully treated infants. As dialysis is now used at an early stage, the survival rate is over 95 percent.
In some cases, despite successful treatment and normalization, renal insufficiency can still occur years later. Up to 70 percent of patients with atypical haemolytic uraemic syndrome develop terminal renal insufficiency, leading to the need for dialysis and, in the long term, a kidney transplant.
