The vast majority of people experience it only as an unpleasant bout of diarrhea or abdominal pain, but an estimated 5,000 to 9,000 Americans die each year from food poisoning, according to the Centers for Disease Control and Prevention.
In the past decade, as medical experts have sought out the source of certain chronic illnesses, they have increasingly found links to episodes of food poisoning, sometimes many years beforehand, according to the CDC.
Campylobacter, a bacterium associated with raw chicken, is now recognized as a leading cause of the sudden acute paralysis known as Guillain-Barre syndrome. Certain strains of salmonella, the bacterium involved in the recent outbreak in Mexican raw jalapeno and serrano peppers, can cause arthritis. And E. coli O157:H7, a strain of an otherwise harmless bacterium that lives in animal intestines, can release toxins that cause hemolytic uremic syndrome, or HUS, a kidney disorder that in 25 to 50 percent of cases leads to kidney failure, high blood pressure and other problems as much as 10 years later, including the risk of birth defects.
Until recently, doctors were focused on the acute phase of food-borne infections, but since the 1990s, there has been "a more gradual recognition that some of the pathogens do have long-term (effects)," said Marguerite Neill, an infectious-disease specialist who teaches at Brown University.
Researchers and clinicians face unique challenges when studying the long-term effects of HUS. The first outbreak associated with E. coli in the United States was in the 1980s. Many of the earliest victims are only now entering their childbearing years.
Also, the number of HUS cases is small. Only about 5 to 10 percent of the 73,000 people each year who get sick from E. coli develop HUS.
The impact of HUS, however, is great. In the acute phase, microscopic blood clots may form in the kidney, leading to kidney failure, Neill said. Sometimes the kidney can be rescued with temporary dialysis. There may be permanent damage to the kidney. Less commonly, these blood clots form in organs such as the brain and cause stroke or seizure.
According to a long-term study of 157 HUS victims co-written in 1994 by Andrew Pavia, an infectious-disease expert at the University of Utah, more than half developed kidney problems seven or more years after the initial illness.
These people face a lifetime of medical treatment. "Anyone with HUS will be monitored for the rest of their lives. If the acute course was severe enough, the risk of long-term kidney complications, including end-stage renal disease and kidney transplant, is quite high. The future medical cost alone can then be in the millions," said William Marler, a Seattle lawyer who sues retailers and food companies on behalf of food poisoning victims.
That is the scenario Elizabeth Armstrong faces. Her two daughters got sick after eating bagged baby spinach in 2006. Her older daughter, Isabella, who was 4 at the time, survived with no apparent health problems. But her younger daughter, Ashley, who was 2 at the time, developed HUS. She has only 10 percent kidney function and will likely need more than one kidney transplant in her lifetime, including one before she is an adult.
There may be a way to prevent the worst HUS cases and their consequences. Doctors in Washington state have found that it is important to hydrate a patient if they even suspect an E. coli infection. Doing so helps reduce the extent of injury to the kidneys. More research needs to be done to identify other effective interventions, said Phillip Tarr, an HUS expert at Washington University School of Medicine in St. Louis.
"There is a lot we don't know yet," Tarr said.