Cryptosporidium hominis and Cryptosporidium parvum subtypes Identified from Patient Specimens in New York State

Background

Cryptosporidium is a pathogenic intestinal parasite that causes cryptosporidiosis, a diarrheal disease common in the US. The predominant species infecting humans are C. hominis and C. parvum. These species can be further classified into families and subtypes by analyzing the sequence of the 60-kDa glycoprotein (gp60) gene. Currently, there are no data available regarding the families and subtypes of Cryptosporidium found in New York State (NYS) or their distribution within the state.

Methods

To address these unknowns the gp60 gene was sequenced to identify the subtypes for C. hominis and C. parvum positive specimens submitted to the Wadsworth Center (NYS Public Health Laboratory) in 2022 and 2023.

Results

All together 634 specimens tested positive for C. hominis, and a subtype family was determined for 613. In 2022 and 2023 IdA16 and IfA12G1R5 were the most frequently identified C. hominis subtypes. Interestingly, IdA16 is typically not found in the US while subtype IfA12G1R5 is currently recognized as the dominant C. hominis subtype.

When assessing C. parvum, there were 489 positive specimens over the 2-year period, and a family and subtype was identified for 466. Subtype family IIa was responsible for a majority of the infections. This family also had the greatest genetic diversity with 30 different subtypes identified throughout the surveillance period.

Conclusions

Laboratory surveillance data such as those presented here, aid in improving outbreak detection and investigations, determine the geographic distribution of subtypes, and identify populations that may be at higher risk for becoming infected with Cryptosporidium.