Erin was one of at least 15 people, and probably as many as 51, sickened by E. coli infection traced to the farm animals.
More than a year after the public attention faded, Erin still suffers the devastating effects from what started as a simple family outing.
The disease so badly damaged Erin's system that she has been on dialysis for 15 months, much of her colon was removed, her kidneys were taken out just before Christmas, and she is scheduled for a kidney transplant next week.
Her father will be the donor.
"I had no idea you could contract E. coli from a petting farm," Rick Jacobs said.
The Centers for Disease Control and Prevention concluded last spring that the potentially lethal strain of bacteria, E. coli 0157:H7, that sickened so many visitors to Merrymead in Worcester, Montgomery County, was also present in 28 cattle tested at the farm.
The bacteria were found on a railing in a petting area where children congregated.
Now, Erin, an animated 4-year-old with blond hair and blue eyes, spends 12 hours a week hooked up to a hospital dialysis machine.
She's heard her medical history so many times that she matter-of-factly explains her plight: "I touched a cow and put fingers in my mouth," she says, "because there wasn't a sink."
Erin was very sick when she was admitted to Alfred I. duPont Hospital for Children in Wilmington, but doctors had every reason to think she would make a full recovery.
She was suffering from a condition called hemolytic uremic syndrome, which begins with bloody diarrhea and is characterized by anemia and kidney failure and, sometimes, neurological problems. A powerful toxin released by the bacteria was damaging the small blood vessels of her kidneys, causing a breakdown of red blood cells, said Shermine Dabbagh, chief of nephrology at duPont.
Each year in the United States, about 74,000 people get sick from E. coli 0157, often from eating contaminated meat. About 2,000 are hospitalized, and about 60 die.
Doctors began dialysis because Erin's damaged kidneys could not adequately filter her blood and remove wastes. Usually, such dialysis is temporary; about 85 percent of patients with hemolytic uremic syndrome regain normal kidney function.
But Erin's kidneys did not rebound, and her hospital stay stretched into weeks, with moments when the Jacobses were sure their daughter would die.
Rick Jacobs, 37, a production worker for an electronics firm, and Trish Jacobs, 35, an accountant at a marketing company, juggled the round-the-clock demands of having one child in the hospital and another at home in Jeffersonville, Montgomery County. Rick's parents were in the midst of moving from the Poconos to Florida but went instead to care for Kelly, now 8. They have yet to leave.
Erin was also seriously disoriented, a possible sign that the E. coli toxins were affecting blood vessels in her brain. She hallucinated that her room was populated by dogs, bad men, purple lights, even Angelica of the Rugrats. She was largely unresponsive for days as her frightened parents kept vigil.
"When she would open her eyes and look at you, it was scary," Rick Jacobs said. "There was no color in her eyes. They were pure black."
She finally went home from the hospital on Dec. 19, 2000, still undergoing regular dialysis because her kidneys were not functioning properly. Then, after Christmas, Erin developed horrible abdominal pain again. "Why did you do this to me?" she asked her parents.
Tests showed her colon was so inflamed from the infection that part of it had narrowed.
So it was back to the hospital for surgery. On Feb. 19, 2001, she went in for what was to be a short procedure to remove an inch of colon. Six hours later, the doctors told the family that Erin's colon was in such bad shape that they had to remove 70 percent of it.
Erin recovered quickly and was soon eating voraciously.
"There was no stopping her," Trish Jacobs said. "She'd wake up at 3 in the morning and say, 'Mom, I want pancakes.' "
Erin's name was put on a nationwide list of people in need of a kidney, but because she could have waited indefinitely for a transplant, her parents decided that one of them would donate a kidney. Each has the same blood-type as Erin, O positive, and Rick felt strongly that he wanted to be the donor.
"Someone has to do it, and someone has to be left to pick up the pieces," Trish Jacobs said.
Even with that life-altering decision, progress has been slow. The transplant has been repeatedly delayed, once on the eve of surgery last June, when tests showed Erin was producing an antibody that would attack the donor organ. Tests last week showed that Erin no longer has the antibody and that her father is a suitable donor.
Another low point for the family was just before Christmas, when, as a way to control Erin's high blood pressure, she was taken into surgery again to remove her damaged kidneys.
From a technical standpoint, next week's transplant is not unusual. A surgical team headed by Stephen Dunn will remove Rick's left kidney as Erin is prepared for surgery. Dunn said the success rate is good for transplants using a related donor: About 97 percent of transplanted organs are functioning well after one year.
Even though the organ is from her father, Erin will always have to take powerful antirejection drugs, which can have significant side effects. Because she is so young, she may need another transplant because transplanted kidneys, on average, last about 30 years, Dunn said.
Knowing they face millions of dollars in lifetime medical bills, the Jacobses filed suit against Merrymead Farm and the county health department; they also are working with a state legislator to pass a law that would require strict controls on petting zoos and farms.
Merrymead and local health officials came under fire for not alerting the public sooner that E. coli was turning up in farm visitors.
Trish and Rick Jacbos, high school sweethearts, have learned from the travails of the last 15 months not to look too far into the future. They don't waste time pondering whether Erin will have a full life, whether she will fall in love, get married, have children.
"Our goal is to get through this and still let her have her childhood," Trish Jacobs says.
Rick Jacobs has explained to Erin in simple terms what will happen with the transplant: "I have two kidneys, and I'm going to give one to you so hopefully you won't need dialysis anymore."
But Erin seems more intent on other things - a game of hide-and-seek with sister Kelly, or building a snowman.
After last week's snowfall, she said: "It wasn't fluffy enough, and it had these small, sprinkly things. I couldn't make a snow angel with it."
Susan FitzGerald's e-mail address is firstname.lastname@example.org.