AMD Projects: Detecting Intestinal Diseases

Before the AMD program began in 2014, no genomic sequences of Cyclospora cayetanensis were available. To diagnose C. cayetanensis as the cause of someone’s illness, laboratory scientists had to identify the parasite in a person’s stool sample. But these outbreaks often went unsolved because we had no way of comparing the strain of C. cayetanensis that infected a person with a strain of C. cayetanensis found in a food source.

Using AMD methods, CDC scientists, along with colleagues from the U.S. Food and Drug Administration (FDA), state public health departments, and academic institutions, have developed the first ever process to acquire genomic sequences from C. cayetanensis. The complex process involves obtaining a pure sample of C. cayetanensis from human stool samples, breaking open the parasite’s extremely strong outer wall, extracting the small amount of genetic material available, sequencing that genetic material, and then analyzing the genomic data to allow comparison of various strains. Through this work, CDC has obtained genomic sequences from 19 samples. In collaboration with colleagues at the FDA, they are addressing the challenge of developing tools that reliably compare and match genomic data from parasites found in food to those found in human stool samples. In 2017, investigators will continue evaluating potential genetic markers for identifying various genotypes of C. cayetanensis and improving detection of the parasite in humans and food sources. This work will help us develop a laboratory-based surveillance system for cyclosporiasis that will identify and help us stop outbreaks faster.