Pennsylvania health authorities said Tuesday that the number of confirmed cases in an outbreak of Campylobacter infection has risen to 20  – 16 from that state and 4 from Maryland.

All of the people who are sick had consumed unpasteurized milk from The Family Cow dairy in the Chambersburg area, according to a report in The Patriot-News.

Pennsylvania and Maryland departments of health issued a health alert on Friday advising people to discard to any products purchased from the farm after Jan. 1.

The Pennsylvania Department of Agriculture is testing samples collected Friday and Monday from the dairy. Results are expected Wednesday or Thursday, according to department spokeswoman Samantha Krepps.

The Family Cow voluntarily stopped selling milk, but owner Edwin Shank has said an independent lab retained by the dairy tested samples taken Friday and reported that batch of milk was free of pathogens.

News reports said those stricken with campylobacteriosis began getting sick about two weeks ago. The incubation period for Campylobacter  — the time between ingesting the bacteria and the start of symptoms – can range from 2 to 10 days. The shelf life for raw milk is about 10 days.

The Family Cow is one of 153 farms licensed by the Pennsylvania Department of Agriculture to sell raw milk and raw milk cheese in Pennsylvania. Maryland prohibits the sale of unpasteurized milk.

According to the Centers for Disease Control and Prevention, most people who become ill with campylobacteriosis get diarrhea, cramping, abdominal pain and fever that typically lasts one week. Some infected persons do not have any symptoms.

About one in every 1,000 reported Campylobacter illnesses leads to Guillain-Barré syndrome, and can result in paralysis. The CDC estimates that as many as 40 percent of Guillain-Barré syndrome cases in the U.S. may be triggered by campylobacteriosis.