Local health authorities are highlighting the dangers of consuming unpasteurized apple cider, with the Ogle County Health Department in Illinois warning that it may contain harmful bacteria that can severely sicken people, especially vulnerable populations.

"Apple cider is a beverage made from fresh apples," the health department wrote in a Facebook post last month. "It is typically a bit murky and golden-colored because it's unfiltered and unpasteurized. Most apple orchards don't take the time to pasteurize because it is not required."

On Facebook last month, the Fulton County Health Department in Illinois noted that foodborne illness can be especially severe and even life-threatening for infants, young children, pregnant women, older adults and people with weakened immune systems.

In 2015, unpasteurized apple cider made on a private dairy farm for a fall festival in Illinois was blamed for a gastrointestinal illness outbreak that sickened more than 100 people.

Attendees from five states and 10 Illinois counties, ranging in age from less than 1 to 89, reported experiencing bloody diarrhea, stomach cramps and bouts of vomiting.

In a lawsuit, one couple said they became "violently ill" after drinking several samples of the cider and bringing a container home with them.

Officials said the cider contained cryptosporidium, a tiny parasite that can cause watery diarrhea.

Authorities noted that cattle, known to carry cryptosporidium, were near the cider press.

Most juices sold in the US are pasteurized, which means they have been heated to kill harmful bacteria, yeasts and molds.

The US Food and Drug Administration requires packaged unpasteurized juices in the refrigerated sections of grocery stores, health-food stores, cider mills or farm markets to have a label that reads: "WARNING: This product has not been pasteurized and therefore may contain harmful bacteria that can cause serious illness in children, the elderly, and persons with weakened immune systems."

However, juices sold by the glass at apple orchards, farmers markets, roadside stands or juice bars are not required to bear that warning.

One health agency recommends pasteurizing the juice at home by heating it to 70 degrees Celsius for at least one minute.

Healthline Nutrition Editor Lisa Valente, a registered dietitian, told The Post if there's any doubt about pasteurization, be sure to ask the vendor.

"Farmers markets are part shopping and part social experience," she said in June.