Kansans might feel a little queasy looking at the state’s reported gastrointestinal illnesses in 2015, but officials say an increase from the previous year likely reflects improved detection technology.
Reports from the Kansas Department of Health and Environment show increases in campylobacteriosis, cryptosporidiosis, salmonella, shiga toxin-producing E. coli and shigellosis.
That doesn’t necessarily mean that the food supply was any less safe, however, or that the public decided to adopt riskier habits. Cases of cryptosporidiosis and shigellosis more than doubled, but the state didn’t record any significant outbreaks of gastrointestinal illness, said Charlie Hunt, director of KDHE’s Bureau of Epidemiology and Public Health Informatics.
He said much of the increase comes from adopting a newer form of testing that is more sensitive than the previous process, leading to more confirmed cases.
In the case of campylobacteriosis, the definition also broadened, Hunt said. The epidemiologists heading the 50 states decided in 2015 to count not only when they grew campylobacter in a sample but also when they detected a protein the bacteria produced, he said.
“We’re counting more cases based on the new definition,” he said.
Many people choose not to seek health care if they have general symptoms of gastrointestinal illness, meaning their cases go unreported. If they do seek care, however, their provider can take a sample for testing.
Traditionally, the lab has to grow the bacteria in the sample to determine what caused the person’s illness, Hunt said. The process could take multiple days, he said, and sometimes the bacteria wouldn’t grow and the lab couldn’t conclude what made the person sick.
“We’re probably detecting more and smaller outbreaks,” he said.
The new process, called a polymerase chain reaction (PCR) test, involves screening for DNA from bacterial species that could have caused the person’s illness, Hunt said. That makes it more likely to find cases that the old method would have missed, and to find them faster, he said.
“A PCR test can work in a matter of hours instead of days,” he said.
That doesn’t mean growing bacteria in labs is irrelevant. Hunt said growing the bacteria is still the best way to sequence their DNA, allowing epidemiologists to determine if multiple cases of the same illness have a common cause. The more information they can find, the easier it will be to pinpoint where there could be a danger to public health, he said.
“It’s very difficult, if you’re doing case investigations, to ask people, ‘Tell me everything you ate and where you purchased it for the last seven days,’” he said.