Last night reports out of Pennsylvania indicated that 3 year old Avala Pierce is undergoing dialysis at the Hershey Medical Center in Hershey, PA. The source of the E. coli infection that caused Avala’s illness is still under investigation, as she may be part of a cluster of 3 kids who developed hemolytic uremic syndrome, or HUS, recently in the Chambersburg PA area.

At the end of July on the other side of the country, an elderly woman in Washington County, Oregon, died from an HUS illness that she developed after eating E. coli contaminated strawberries. She was one of two people sickened by E. coli O157:H7 in the strawberry outbreak to develop HUS.

What is HUS?

The young, the elderly, and even otherwise strong and healthy adults can suffer devastating HUS illnesses.  See the story of Stephanie Smith, a Marler Clark client whose dance career was cut short by E. coli and HUS. 

Post-diarrheal hemolytic uremic syndrome (D+HUS) is a severe, life-threatening complication that occurs in about 10 percent of those infected with E. coli O157:H7 or other Shiga toxin- (Stx-) producing E. coli. D+HUS was first described in 1955, but was not known to be secondary to E. coli infections until 1982. It is now recognized as the most common cause of acute kidney failure in infants and young children. Adolescents and adults are also susceptible, as are the elderly, who often succumb to the disease.

The bowel inflammation that occurs prior to the onset of post-diarrheal hemolytic uremic syndrome (D+HUS) is generally referred to as the prodrome. Within a week (range 1-10 days) after ingesting Stx-producing E. coli, the colon becomes severely inflamed causing diarrhea that soon becomes bloody. A stool specimen obtained at this point is usually positive for E. coli O157:H7 or Shiga toxin. However, in many patients the window for capturing E. coli O157:H7 is narrow.

During the prodromal phase of HUS, the initial diagnosis is often acute surgical abdomen, acute appendicitis, or ulcerative colitis. The large bowel inflammation (colitis) can be mistaken for acute appendicitis because the site of intense inflammation is in the right lower part of the abdomen. If this leads to an appendectomy, the appendix is almost always found to be normal, but the surrounding bowel is swollen and hemorrhagic. If a colonoscopy is conducted, severe inflammation, ulceration and pseudomembranes (comprised of sloughed mucosal cells, white blood cells, and fibrin) are found.

When a patient is diagnosed with post-diarrheal hemolytic uremic syndrome (D+HUS), the hospital course can range from mild to very severe. Children are generally in the hospital for about two weeks (range 3 days to 3 months), and adults longer, as their course tends to be more severe. Since there is no way to stop the progression of D+HUS, supportive therapy, including meticulous attention to fluid and electrolyte balance, is the cornerstone of survival.

The inflamed colon is usually non-functional for a week or two, so total parenteral nutrition (TPN) needs to be administered through a peripherally inserted central catheter (PICC). This provides access to a large vein in the upper chest that allows infusion of highly concentrated glucose. Even after intestinal function recovers most patients continue to have a poor appetite for a week or so longer. During this interim, nutrients may need to be given through a nasogastric (NG) tube.

Reduced or absent urine output (oligoanuria) occurs in most cases and usually lasts about a week, but can be as brief as two to three days, or as long as a month or greater. Dialysis is required during this time to cleanse the body of uremic toxins and to maintain fluid and electrolyte balance. Peritoneal dialysis (PD) is usually used for young children unless the colitis is severe. Fortunately, the colitis is often resolving by the time peritoneal dialysis becomes necessary. Treatment requires placement of a catheter (tube) through the abdominal wall into the peritoneal cavity. Older children and adults are treated with hemodialysis that circulates blood through a hemodialysis machine to filter out (remove) uremic toxins, normalize blood chemistries and correct any edema (swelling). This requires that venous access be established by inserting a temporary catheter into a major vein that returns blood from the upper body to the heart.

The majority of HUS victims require one or more blood transfusions to treat severe anemia; platelet transfusions are sometimes needed to diminish the risk of bleeding in those with severe thrombocytopenia (i.e., platelet counts less than 10,000), to control bleeding, or in preparation for an invasive vascular procedure that can cause hemorrhage (e.g., insertion of a hemodialysis catheter).

More than half of patients experience high blood pressure (BP) that is usually mild and labile, but may be severe enough to require treatment with anti-hypertensive drugs. This condition usually resolves prior to, or soon after discharge from the hospital.

One has to remain vigilant for signs of extra renal involvement. Intestinal necrosis (death) and perforation can occur at any time during the acute phase of the disease and can be fatal if not promptly diagnosed and surgically treated. Pancreatic damage can cause sugar diabetes that is almost always temporary, but may require insulin. Heart and lung injury is rare, but can be fatal. Brain damage can cause stroke and/or cerebral edema (swelling of the brain), and is the most frequent cause of death.

More frequently, however, the encephalopathy (brain dysfunction) is the result of acute metabolic imbalance (metabolic encephalopathy) and is due to abnormalities in the blood concentrations of sodium, glucose, calcium, or to very high levels of metabolic waste products. Since these metabolic abnormalities are the result of the acute kidney failure, they can be corrected by dialysis, and the outcome is favorable. The prevalence of metabolic encephalopathy 25 or more years ago was about 50 percent. With earlier diagnosis and more timely treatment, the prevalence is now down to about 25 percent. Convulsions are the most dramatic manifestation, and are more likely to occur in toddlers (30 percent) than older children (15 percent). Unfortunately, structural damage to the brain (i.e., stroke, swelling) has not decreased over time. When swelling is severe, the pressure strangulates the brain stem that is responsible for maintaining blood pressure, heart rate, and breathing. This usually results in rapid death.