The bacteria’s molecular fingerprints first surfaced in New Jersey. They then popped up in Pennsylvania and New York, sprouted down south to Georgia, and migrated out west to California.
E. coli had left its distinctive DNA mark on the leaves and in the veins of romaine lettuce grown in Arizona and shipped out nationwide. In just a few weeks, patrons eating salads and sandwiches from a cafe in Warren County, New Jersey and inmates at a correctional facility in Nome, Alaska, contracted the deadly bacterium.
So far, one person from California has died, and 121 people from 25 states have become ill in the latest E. coli outbreak, according to the latest alert from the Centers for Disease Control and Prevention (CDC). More than half of them have been hospitalized, including 14 who developed a type of kidney failure called hemolytic uremic syndrome.
For health officials who monitor infectious diseases, this latest E. coli surge is among the worst multistate outbreaks in more than a decade.
But experts say that the continued spread of this outbreak doesn’t point to a breakdown among epidemiologists.
Instead, the fact that the state and federal system that collects, tracks, then matches the molecular pattern or fingerprints of the bacteria was able to detect an outbreak that spread among more than two dozen states shows that the system is working.
Right now, it allows federal officials to spot an outbreak faster than ever before, then issue warnings.
Without the system, experts say, the spread of Escherichia coli O157 — which can cause kidney failure and even death — could be worse.
“We’re diagnosing more precisely to trigger a response mechanism to send disease detectives to the fields,” said Dr. William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine. “Now those troops can be deployed much more rapidly. This is a terrific scientific advance developed over the last 20 years.”
How ‘disease detectives’ fight an outbreak
The system leans on local hospitals to send suspected E. coli samples from patients to state laboratories, usually inside health departments. Molecular techniques are then used to break down the E. coli to its genetic components.
Like other bacteria, E. coli strains have their own distinctive DNA fingerprint.
If those fingerprints start to match, state health officials then submit them to a national laboratory network called PulseNet, in place since 1996. The system uses that DNA fingerprinting to detect local and multistate outbreaks.
Health officials, known in the trade as “disease detectives,” fan out and interview patients and doctors to gather information on what was consumed and where.
“It’s almost like ‘CSI,’” said Schaffner, referring to the popular television series. “These are very intense investigations. People work long hours, even weekends, to try to trace these. With E. coli, you can eat them one day and not get sick until a week later. People forget what they ate, and where they ate it.”
It can take two to three weeks before an outbreak is detected, said Laura Whitlock, spokeswoman with the CDC’s Outbreak Response and Prevention Branch.
The latest outbreak may have begun in mid-March. On April 13, the CDC issued a warning urging consumers nationwide to not eat any romaine lettuce. Though officials with the U.S. Food and Drug Administration knew the lettuce had come from Yuma, Arizona, the alert had no additional information for consumers about which brand of lettuce to avoid.
Whitlock acknowledged the move to issue an alert without more specifics was unusual. But she said lettuce has a short shelf life, and connecting it to a farm and distribution center is complex and takes time. The public had to know.
She also said there may be more cases out there.
“For every one case of E. coli O157 we hear about in our system at CDC, there are estimated to be another 26 people that go unreported to us,” she added.
What exactly is E. coli?
E. coli is a group of bacteria that live in the intestines of humans and animals. Many are harmless, but some strains can cause illness. It’s still unknown how the bacteria spread to the romaine lettuce in the latest outbreak, but the most common way includes animal waste coming into contact with crops.
Symptoms of E. coli infections don’t emerge until almost a week after eating contaminated food. Those symptoms can range from being very mild and not life-threatening to bloody diarrhea, severe stomach cramps, and vomiting.
Since E. coli O157 creates a toxin known as Shiga toxin, some people could experience a severe symptom called hemolytic uremic syndrome that can lead to kidney failure. Young children and older adults, especially those with weakened immune systems, are more likely get sick.
The best way to avoid most pathogens is to wash fruits and vegetables and cook meats well, said Dr. Claudia Hoyen, director of pediatric infection control and pediatric innovation at UH Rainbow Babies and Children’s Hospital in Cleveland, Ohio.
“It’s even as simple as washing your hands really well,” Hoyen said. “Virus and bacteria have a way of mutating themselves and are one step ahead of us. They’ve been around for millions of years and have learned to keep themselves viable.”