Pennsylvania has been added to the list of states in an outbreak of cyclosporiasis, an intense intestinal illness. 

The Centers for Disease Control on Friday included Illinois, Kansas, Oklahoma and Pennsylvania in the outbreak, joining Indiana, Kentucky, Michigan, Ohio and West Virginia. The agency has reported almost 2,000 confirmed cases associated with this multistate outbreak that's been linked to lettuce served at Taco Bell and is aware of more than 5,000 probable cases that have yet to be confirmed. 

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The CDC defines something as an outbreak when there are more cases than what is typical in a given time, within a specific location or for a specific population. 

Cyclosporiasis is an intense stomach bug that causes extreme diarrhea which is caused by the cyclospora parasite. It is typically contracted by consuming food or water that came into contact with feces containing cyclospora eggs. Symptoms can take up to two weeks to appear after coming into contact with the parasite.  

Late last week, health officials tied the outbreak to lettuce served at Taco Bells and supplied by Taylor Farms de Mexico. The CDC said that 1,947 reported "exposure to Taco Bell" in the nine states in the two weeks before symptoms appeared. Taylor Farms has voluntarily recalled lettuce supplied to 27 states, including Pennsylvania and New Jersey. 

Thus far, epidemiologic and traceback data have indicated that Taylor Farms is the source of the outbreak, but experts haven't been able to secure a positive test in a lab. However, technicians can't grow cyclosporiasis in a lab, so generating evidence can be increasingly difficult.