Answer to Case 719

 Answer to the Parasite of the Week 719: Cyclospora sp. oocysts. 

While Cryptosporidium spp. oocysts have a similar appearance, they are smaller than Cyclospora oocysts, measuring only 4-6 micrometers in diameter. 

Note that Cyclospora oocysts do not stain uniformly with either the modified acid fast or modified safranin methods, although there tends to be fewer unstained oocysts with the latter. The microwave modification of the safranin stain will also improve the staining uniformity (see the CDC procedure HERE).

As Dr. Marc Couturier pointed out on Twitter, there are now three morphologically-identical species of Cyclospora known to cause human infection: C. cayetanensis, C. ashfordi, and C henanensis. Therefore it is best to report this finding out as "Cyclospora species."

Lastly, Idzi discussed in the blog comment sections why this finding is so timely. Every year now in the past decade, the U.S. has seen summer outbreaks of cyclosporiasis linked to imported produce (e.g., cilantro, basil, snap peas, lettuce, raspberries) from Latin America. Infection is transmitted to humans through ingestion of fecally-contaminated food and water. Therefore, infection originates from regions where there is poor sanitation and lack of access to clean water.