Two North Carolina cases have now been tied to a multistate outbreak involving shredded lettuce. In North Carolina, many of those samples during this summer’s historic rise in cases have been sent to Quest Diagnostics. Quest Diagnostics is one of the country's largest medical testing companies. MacIntyre told WRAL that Quest Diagnostics has 10 laboratories nationwide that are capable of running tests for the Cyclospora parasite. North Carolina urgent care physicians have also said delays can occur when patients don't return their stool samples for testing.