A Close Encounter with E. coli O157: A Young Girl and Her Family’s Recent Life-Changing Experience
Four-year-old Rachel Peck, like most children her age, loves animals. The Frankford, Ontario family’s visit to a petting zoo at a major Canadian agricultural exhibition on August 28, 2010 was not out of the ordinary. Then three-year-old Rachel and her six-year-old sister Julia enjoyed feeding the calves and other baby animals at the zoo.
Although it has not been confirmed, it is highly suspected that a severe gastrointestinal illness that hit Rachel a few days following the petting zoo visit is a result of a transfer of bacteria from the petting zoo animals to her. Rachel first suffered diarrhea within 24 hours after being at the zoo. Two days later, her stool had blood in it and Rachel’s parents - Danielle and Wes - took her to the local hospital emergency department to have her checked. Overnight, Rachel was transported to The Hospital for Sick Children in Toronto (“Sick Kids’”) with suspected intussusception of the bowel, where one portion of the bowel slides into the next, much like the pieces of a telescope. When this occurs, it creates an obstruction in the bowel, with the walls of the intestines pressing against one another, causing swelling, inflammation, and decreased blood flow to the intestines involved.
This diagnosis was ruled out at Sick Kids’, but an ultrasound examination showed that Rachel’s colon was grossly inflamed. The diagnosis was changed to infectious colitis (infection in the colon), with a treatment of hydration and overnight observation. The next day, Sick Kids’ staff suggested that Rachel could be discharged. A stool sample was positive for Escherichia coli (E. coli) O157:H7, but it was recommended that, with hydration, Rachel should recover within 7 to 10 days. It was, however, noted that about 10% of E. coli infections can lead to haemolytic uremic syndrome (HUS), a condition characterized by the breakup of red blood cells (haemolysis) and kidney failure. A list of symptoms was provided to Rachel’s parents to watch for, all of which – if they appeared - would require a quick return to the hospital.
Sure enough, within 24 hours, Rachel developed one of the symptoms on the list: Her urine was the colour of dark tea. She had also started to vomit. At the local emergency department, Rachel’s blood was taken to check for kidney function. The assessment: Renal (kidney) failure. Rachel’s kidneys were shutting down. An air ambulance was called and she was sent back to Sick Kids’ Intensive Care Unit.
Her parents fear and worry about Rachel’s deteriorating condition became full-blown panic when told that heavy winds meant neither parent could travel with Rachel on the air ambulance. “When the ambulance left the hospital to take her to the helipad, I started to hyperventilate,” says Danielle. “I honestly didn't know what her condition would be when we got to Toronto and it broke my heart wondering if she was afraid without one of us with her.”
Sick Kids’staff tried to induce urination with a diuretic, but Rachel’s urine output was very low. They inserted a femoral line and started haemodialysis, a technique of removing waste materials from the blood using an external filtering machine, along with a blood transfusion as her haemoglobin was quickly dropping. After one week of this treatment, Rachel’s temperature spiked and it was identified that her femoral line and peripheral sites were infected with E. coli O157:H7. Hospital staff had to remove the line and insert a peritoneal catheter for peritoneal dialysis. After two weeks, the dialysis was stopped and Rachel’s own small kidneys went back into production. During that time, Rachel had received four blood transfusions, one albumin transfusion (the main protein in human blood and the key to the regulation of the osmotic pressure of blood), an injection of erythropoietin (EPO), a hormone produced by the kidney that promotes the formation of red blood cells in the bone marrow, and four different antibiotics. Having been stuck in bed for weeks with little movement, a physiotherapist had to be employed to help Rachel walk again.
Since returning home on September 30th, Rachel’s health has steadily improved. In spite of the ongoing monitoring that has included daily blood sampling, weekly blood pressure checks, once-a-month checkups at Sick Kids’ and a special diet with no potassium and low in phosphorus, sodium and dairy products, Rachel now shows all the signs of a normal, healthy four-year-old (she had her 4th birthday on March 10th), with the exception that her activity level is not what it used to be. Her haemoglobin only recently returned to a normal value. She also becomes irritable quickly, which is a common symptom of HUS that everyone is hoping will gradually diminish. Rachel’s parents are watching her health very carefully, and have been advised that she will be followed by a nephrologist (kidney specialist) for life.
The experience has been a life changing one for Rachel’s family. “We certainly don't take anything for granted anymore and we try to embrace every single moment with the kids,” says Danielle. “Rachel’s 4th birthday was a very big celebration for us, since there were times during the course of Rachel's illness where we were not certain if she would be around for her 4th birthday. We are very thankful that she was.”
“The whole experience has instilled some fear in us. We try to avoid any activity where we might come in contact with E. coli out of fear that Rachel may be at a higher risk of relapsing if she contracts it again. We did, however, take them to pick pumpkins in October, but after we were done the whole family needed to be "decontaminated" with alcohol rinse. I think we are probably a little too cautious now at times but the fear of going though that experience again is the cause.”
Dr. Colin White, a paediatric nephrologist from British Columbia, has many years of experience with such cases. He calls HUS one of the most challenging diseases he and his colleagues face. “This particular bacterium releases a poison into the bloodstream that damages cells within the lining of the blood vessels. The blood vessels shrink in size which leads to damage and breakdown of both the red blood cells and the platelets. Because of the large number of blood vessels in the kidneys, this damage does lead in many people to quite significant renal damage. The vessel damage can actually cause problems with any organ in the body, more commonly the pancreas, liver, brain and occasionally, lungs and heart.”
Renal damage from HUS can be quite severe in some patients and, even many years after the actual illness, may lead to the need for chronic dialysis and transplantation. Similarly, some studies suggest that there may be long-term gastrointestinal tract damage from the infection, leading to colitis or other gastrointestinal illnesses.
About E. coli O157:H7
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Escherichia coli (E. coli) is a fecal coliform bacterium that is commonly found in the intestines of animals and humans. Hundreds of E. coli strains exist, most of which normally inhabit the human intestine and cause no disease. However, E. coli O157:H7 produces powerful toxins that can cause severe illness in humans.
E. coli O157:H7 was first recognized as a cause of illness in 1982 during an outbreak of severe bloody diarrhea in the United States, which was traced to contaminated hamburgers. As of 2009, more infections in the United States have been caused by eating undercooked ground beef than by any other food. In recent years, produce contamination has become an increasing source of human infection. Despite the substantial gains in knowledge about E. coli O157:H7 since its recognition, many fundamental questions and concerns remain. The reasons for the original emergence of this pathogen and for its geographic spread are likely due to genetic recombination between bacteria, yielding a new strain. In recent years, the organism has become a global health problem. In 1996 alone, major outbreaks were reported in Germany, Scotland, and Japan. The largest of these outbreaks, in Japan, affected approximately 9,000 persons and was traced to contaminated radish sprouts.
E. coli O157:H7 infection is a foodborne “zoonotic disease”, where illness is the result of transmission through food from an animal source, usually cattle. Infection caused by Salmonella, Campylobacter, and Cryptosporidium parvum also fall under the category of “zoonotic disease”.
The Effects of E. coli O157:H7 Infection on Human Health
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E. coli O157:H7 is an important human pathogen. Onset of illness generally occurs two to eight days (average of 3-4) following exposure to the bacteria. Once the bacterium is ingested, it makes its way through the digestive system, where it attaches to the cells lining the intestine. The infection causes inflammation which damages the intestinal lining and facilitates entry of the toxin into the circulatory system. Symptoms of infection include abdominal pain, followed by severe bloody diarrhea. Fever is rare, but vomiting is sometimes associated with the infection. In most cases, the illness resolves in 5 to 10 days. People who only have diarrhea usually recover completely.
However, in about 8-10% of severe cases the toxin can cause the development of haemolytic uremic syndrome (HUS), usually with children under five years of age and elderly people being the most susceptible, leading to death in approximately 2-7% of cases (World Health Organization). The toxin targets and enters glomerular cells in the kidneys causing cell death and membrane damage, which in turn prompts platelet activation and coagulation providing the characteristic feature of thrombotic microangiopathy (TMA). This renal damage manifests as a host of clinical features which can rapidly progress and can lead to acute renal failure and neurological complications such as seizures and strokes. Approximately 30-40% of HUS patients develop one or more long-term complications including colitis, hypertension, proteinuria and progressive renal insufficiency.
E. coli O157:H7 in Cows
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Ruminant livestock, including cattle, deer, goats, and sheep, have been found to harbour E. coli O157:H7 in their intestines. Cattle are considered the major reservoir of E. coli O157:H7 worldwide. Numerous studies have demonstrated that incidence in beef and dairy cattle is widespread and that the organism is found in, on, and around cattle in most parts of the world. E. coli O157:H7 does not induce disease in cattle, but the pathogen is known to colonize the intestinal tract of the animal and is frequently shed into the environment (in manure) following this colonization. Thus cattle are considered to be the primary reservoir and source of infection, even though a large variety of foods (and water sources) are implicated in human outbreaks.
Animal Exhibit Transmission
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It is estimated that close to six million Americans visit animal exhibits each year. In the U.S., from 1999 to 2006, seven outbreaks of E. coli-related illness were attributed to animal exhibits, resulting in thousands of people becoming ill, more than 36 cases of HUS, and two deaths.
Petting zoos, fairs, and agricultural exhibits provide many possible routes of transmission for E. coli O157:H7. Animal contact is common, with a large proportion of children participating. Infection can also occur through indirect animal contact, through interaction with contaminated products (e.g., sawdust, shavings, visibly soiled clothes or shoes), or in areas adjacent to contaminating sources, such as playgrounds located near animals. While many petting zoos and fairs educate people about the importance of hygiene and hand washing and provide the proper facilities, it is difficult to monitor compliance.
A 2006 survey of thirty-two U.S. agricultural fairs demonstrated that E. coli O157:H7 is widespread in animals at these exhibits. E. coli O157:H7 was isolated from livestock at 97% of the fairs tested, with 11% of cattle testing positive. This high prevalence is an important consideration, given that millions of people, many of them children, attend and interact with livestock exhibits.