CDC Issues New Guidance For Identifying Cyclospora Infections

With more than 616 cases of cyclospora infections identified nationwide over the past three months, and the likelihood that there is more than one outbreak occurring in the United States, government health officials have released new guidance to help laboratories identify the infection cases.  

This week, the U.S. Centers for Disease Control and Prevention (CDC) published laboratory guidance for identifying infections caused by the cyclospora parasite. The goal is to help laboratories identify the parasites, which could help to determine how many outbreaks are occurring and what is causing them.

In the guidance, the CDC recommends that laboratories use telediagnosis to obtain confirmation of cases from stool samples. Laboratories can use modified acid-fast stains or UV fluorescence microscopy before microscopic examination to capture images of the parasites.

“Cyclospora cannot be identified to the species level using microscopy; molecular methods must be used,” the CDC notes. “At CDC, a nested polymerase chain reaction (Nested-PCR) assay targeting the 18S rRNA gene is the method of choice for Cyclospora species identification, using DNA extracted from human stool specimens. This method has been used by CDC to examine clinical specimens and food samples in different settings and during outbreak investigations.”

If laboratories are able to identify different strains of cyclospora, it could help identify which of the illnesses are related. Those related groups of infected persons could then be investigated to see if they had some sort of common link; whether they all ate at the same restaurant or restaurant chain, purchased the same kind of fruit, or drank from the same water source, for example.

The new guidance comes after the CDC confirmed that cyclospora infections in Texas, the state hardest hit by the outbreaks, were not caused by contaminated salad mixes sold at Olive Garden and Red Lobster restaurants through Taylor Farms of Mexico. Those salad mixes were previously linked to illnesses in Nebraska and Iowa, but the same produce was not distributed to restaurants in Texas. The notification confirmed suspicions that more than one outbreak are currently ongoing.

Cyclospora is a single-cell parasitical organism, which is usually spread through contaminated fresh produce or through drinking water. However, the CDC advised consumers nationwide not to shy away from eating fresh produce in fear of contracting the illness. The agency advised that the health benefits of fresh produce far outweigh the small risk of cyclospora food poisoning.

Since the outbreaks were first detected in late June, health agencies from 22 states have reported illnesses, including at least 45 hospitalizations.