More than 860 North Carolinians have tested positive for Cyclospora this summer. They join thousands of Americans nationwide testing positive for the parasite at levels the country has never seen before.
Two North Carolina cases have now been tied to a multistate outbreak involving shredded lettuce.
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A Cyclospora diagnosis requires a stool sample. In North Carolina, many of those samples during this summer’s historic rise in cases have been sent to Quest Diagnostics.
“It’s been a busy summer, to say the least,” said Dr. Ann MacIntyre, senior medical director for infectious diseases at Quest Diagnostics. “We're having to really bump up the amount of work that our frontline workers are able to, and capable of doing.”
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.
“If you have someone in North Carolina who has symptoms concerning for Cyclospora, and they go into a patient service center and drop off a stool sample, those samples actually are reviewed by your neighbor here in Virginia,” MacIntyre explained. “We do review that in our lab in Chantilly, Virginia.”
Each test requires hands-on examination by a trained laboratory technician.
“It's a manual test using microscopy and special staining,” MacIntyre stated. “The laboratory technicians in our microbiology lab examine the patient-provided stool specimen under a microscope, looking for those parasites.”
That hands-on process is also why MacIntyre says Cyclospora test results aren't immediate.
“It is something that is not as simple as necessarily having a machine do it,” MacIntyre said. “This is true diagnostic infectious diseases at its core: looking at the microscope and seeing what they find, and looking for the characteristic signs of certain parasitic diseases.”
The Chantilly, Virginia lab can typically provide results for Cyclospora tests within two or three days, according to MacIntyre. However, greater demand this summer led to longer turnaround times, and longer hours for staff.
North Carolina urgent care physicians have also said delays can occur when patients don't return their stool samples for testing.
Once Cyclospora is detected, Quest Diagnostics electronically reports the findings back to the state.
“Our testing only is able to determine if a patient actually has evidence of the Cyclospora parasite, or if they don’t,” MacIntyre said. “We cannot confirm what food made them ill, or what gave them symptomatology.”
That work happens through extensive interviews with patients regarding their food histories that are conducted by local and state health investigators.
North Carolina Department of Health and Human Services officials previously told WRAL they sent hundreds of samples to the Centers for Disease Control and Prevention this summer for additional testing.
Together, laboratory results and epidemiological investigations can help health officials connect individual cases to larger outbreaks — including the current multistate investigation involving shredded lettuce.
Michigan reported the first two deaths tied to the ongoing Cyclospora investigation this summer. Deaths from cyclosporiasis infections remain extremely rare.
Patients with GI symptoms lasting several days, including explosive diarrhea, should contact their health care provider about stool sample collection.