Signs and symptoms of HUS can include:
- Bloody diarrhea
- Decreased urination or blood in the urine
- Abdominal pain, vomiting and occasionally fever
- Small, unexplained bruises or bleeding from the nose and mouth
- Fatigue and irritability
- Confusion or seizures
- High blood pressure
- Swelling of the face, hands, feet or entire body
When to see a doctor
See your doctor immediately if you or your child experiences bloody diarrhea or several days of diarrhea followed by:
- Decreased urine output
- Unexplained bruises
- Unusual bleeding
- Extreme fatigue
Seek emergency care if you or your child doesn't urinate for 12 hours or more.
The most common cause of HUS — particularly in children under the age of 5 — is infection with E. coli bacteria that produce certain toxins (shiga toxin-producing E. coli or STEC). One such strain of E. coli is known as E. coli O157:H7. Other strains of E. coli have also been linked to HUS.
E. coli refers to a group of bacteria normally found in the intestines of healthy humans and animals. Most of the hundreds of types of E. coli are normal and harmless. But some strains of E. coli — including those that cause HUS — are responsible for serious foodborne infections.
E. coli can be found in:
- Contaminated meat or produce
- Swimming pools or lakes contaminated with feces
Sometimes, E. coli infection is spread through close contact with an infected person, such as within a family or at a day care center.
Most people who are infected with E. coli, even the more dangerous strains, don't develop HUS.
Other causes of HUS can include:
- The use of certain medications, such as quinine sulfate (Qualaquin), some chemotherapy medications, medications containing the immunosuppressant cyclosporine (Neoral, Sandimmune, Gengraf) and anti-platelet medications
- Certain infections, such as HIV/AIDS or an infection with the pneumococcal bacteria
- Rarely, pregnancy
Susceptibility to an uncommon type of HUS — known as atypical HUS, primary HUS or complement-mediated HUS — can be passed down genetically to children. People who have inherited the mutated gene that causes atypical HUS won't necessarily develop the condition. The mutated gene might be activated after an upper respiratory or abdominal infection.
The risk of developing HUS is highest for:
- Children under 5 years of age
- People over 75
- People with certain genetic changes that make them more susceptible
HUS can cause life-threatening complications, including:
- Kidney failure, which can be sudden (acute) or develop over time (chronic)
- High blood pressure
- Intestinal problems, such as inflammatory colitis
- Heart problems