Unexpected Cryptosporidium species Identified from New York State Clinical Stool Specimens

Cryptosporidiosis is predominantly considered a waterborne illness that occurs after becoming infected with Cryptosporidium parvum or Cryptosporidium hominis, the two species that typically infect humans. However, identifying non-C. parvum/C. hominis species that infect humans could reveal additional behaviors or exposures that contribute to cryptosporidiosis. Here, we identify species, non-C. parvum/C. hominis species causing infections and determine their distribution within New York State (NYS).

To do this, real-time Polymerase Chain Reaction (RT-PCR) was used to prescreen and eliminate samples containing C. parvum and C. hominis. Sanger sequencing and targeted next generation sequencing (tNGS) were employed to identify non-C. parvum/C. hominis species.

During 2022 and 2023, 130 human clinical specimens were determined to contain one of the less common Cryptosporidium species. The two most frequently observed were C. mortiferum (n=38) and C. felis (n=33). The main reservoir hosts for these two species are chipmunks and cats, respectively. Additional species were also observed, although at lower frequencies.

These results highlight the public health importance of non-C. parvum/C. hominis species. This information is valuable not only because it can be relayed to the public with the goal of decreasing infections arising from specific species, but it also demonstrates the utility of molecular epidemiology in assisting with public safety and prevention measures.