The most common form of transmission is ingestion of undercooked meat, unpasteurized fruits and juices, contaminated produce, contact with unchlorinated water, and person-to-person transmission in daycare or long-term care facilities.Unlike typical HUS, aHUS does not follow STEC infection and is thought to result from one or several genetic mutations that cause chronic, uncontrolled, and excessive activation of complement. This leads to platelet activation, endothelial cell damage, and white blood cell activation, leading to systemic TMA, which manifests as decreased platelet count, hemolysis, damage to multiple organs, and ultimately, death. Early signs of systemic complement-mediated TMA include thrombocytopenia (platelet count below 150,000 or a decrease from baseline of at least 25%)  and evidence of microangiopathic hemolysis, which is characterized by elevated LDH levels, decreased haptoglobin, decreased hemoglobin, and/or the presence of schistocytes. Diagnosis
The similarities between HUS, aHUS, and TTP make differential diagnosis essential. All three of these systemic TMA-causing diseases are characterized by thrombocytopenia and microangiopathic hemolysis, plus one or more of the following: neurological symptoms (e.g., confusion, cerebral convulsions, seizures); renal impairment (e.g., elevated creatinine, decreased estimated glomerular filtration rate [eGFR], abnormal urinalysis); and gastrointestinal (GI) symptoms (e.g., diarrhea, nausea/vomiting, abdominal pain, gastroenteritis).The presence of diarrhea does not exclude aHUS as the cause of TMA, as 28% of patients with aHUS present with diarrhea and/or gastroenteritis. First diagnosis of aHUS is often made in the context of an initial, complement-triggering infection, and Shiga-toxin has also been implicated as a trigger that identifies patients with aHUS.
Sacroiliitis is inflammation within the sacroiliac joint. It is a feature of spondyloarthropathies, such as axial spondyloarthritis (including ankylosing spondylitis), psoriatic arthritis, reactive arthritis or arthritis related to inflammatory bowel diseases, including ulcerative colitis or Crohns disease. It is also the most common presentation of arthritis from brucellosis. Symptoms and signs
People suffering from sacroiliitis can often experience symptoms in a number of different ways, however it is commonly related to the amount of pressure that is put onto the sacroiliac joint. Sacroiliitis pain is typically axial, meaning that the location of the condition is also where the pain is occurring. Symptoms commonly include prolonged, inflammatory pain in the lower back region, hips or buttocks.However, in more severe cases, pain can become more radicular and manifest itself in seemingly unrelated areas of the body including the legs, groin and feet.Symptoms are typically aggravated by:
Transitioning from sitting to standing
Walking or standing for extended periods of time
Running
Climbing stairs
Taking long strides
Rolling over in bed
Bearing more weight on one leg

Cause
Sacroiliitis is a condition caused by inflammation within the sacroiliac joint. This joint is located where the base of the spine, known as the sacrum, and the pelvis, known as the ilium, intersect. "Itis" is a Latin term denoting inflammation.Since sacroiliitis can describe any type of inflammation found within the sacroiliac joint, there can be a number of issues that cause it. These include:
Degenerative arthritis, or osteoarthritis of the spine, can cause degeneration within the sacroiliac joints and lead to inflammation and joint pain.