Hemolytic-uremic syndrome (HUS) is a group of blood disorders characterized by low red blood cells, acute kidney failure, and low platelets. Initial symptoms typically include bloody diarrhea, fever, vomiting, and weakness. Kidney problems and low platelets then occur as the diarrhea is improving. While children are more commonly affected adults may have worse outcomes. Complications may include neurological problems and heart failure.Most cases occur after infectious diarrhea due to a specific type of E. coli called O157:H7. Other causes include Strep. pneumoniae, shigella, salmonella, and certain medications. The underlying mechanism typically involves the production of Shiga toxin by the bacteria. Atypical hemolytic uremic syndrome (aHUS) is due to a genetic mutation and presents differently. Though both cause widespread inflammation and multiple blood clots in small blood vessels, a condition known as thrombotic microangiopathy.Treatment involves supportive care and may include dialysis, steroids, blood transfusions, or plasmapheresis. About 1.5 per 100,000 people are affected per year. Less than 5% of those with the condition die; of the remainder up to 25% have ongoing kidney problems. HUS was first defined as a syndrome in 1955.