Summer Surge: Campylobacter Infections on the Rise

Stomach illnesses with diarrhea, nausea, fever, and severe abdominal pain are on the rise. It's the season for campylobacter—a nightmare for vacationers. However, there are ways to avoid the bacteria.

"We see an incredible correlation between the presence in chicken and the number of people affected," says Rikard Dryselius, an investigator at the Public Health Agency of Sweden.

Campylobacter is the most common bacteria causing stomach illness in humans. At least 7,000 Swedes are affected each year.

And summer is the worst period.

"There's always an increase at this time of year. It's incredibly seasonal," says Rikard Dryselius.

Since early June, the number of cases has more than doubled.

The bacteria cause severe diarrhea, nausea, vomiting, fever, headache, and severe abdominal pain—symptoms that can ruin a vacation.

But there are ways to avoid the nightmare.

Chicken is Critical

One way is to be meticulous with chicken handling.

"We see a very strong correlation between the presence in chicken and the number of people affected," he says.

He estimates that about ten percent of all chickens in the summer have campylobacter, but suggests assuming all chicken is infected and being extra careful with hygiene.

"You should have separate cutting boards for chicken that are thoroughly washed. If grilling in the summer, avoid using the same plate before and after, and don't use the same tools for handling raw and cooked chicken," he says.

Even very small droplets can cause infection—and it's difficult to manage.

"An experiment in Denmark a few years ago involved putting fluorescent substances on a chicken while a family cooked. Then they shone a light to see where the chicken droplets landed. They were everywhere, on the oven, on all the counters," says Rikard Dryselius.

Common During Mountain Hiking

There are also other sources of infection. It's estimated that 1 in 20 who fall ill during the summer months are mountain hikers.

"It's tempting to drink cold water from mountain streams. But if there are animals upstream, like birds, that have defecated, you can get infected."

He advises using filters when drinking from mountain streams.

Another source of infection is unpasteurized milk, and one should be cautious if they have their own well.

Municipal drinking water should be safe, says Rikard Dryselius.

"I remember an outbreak in Skåne in the 80s. A colony of gulls had built nests on a water tower, and there were cracks in the roof. The water went to many people, I think 10,000 got sick. But the infrastructure is better today," he says.

Infection numbers are expected to decrease in October or November.

"In December and January, it's not much, and then it's calm until May, and then it starts again."