Cryptosporidium in Finland, 2021
Prevalence and Molecular Characteristics of Cryptosporidium spp. in Humans in Finland, 2021: First Findings of Cryptosporidium Chipmunk Genotype I in Finland  The aims of the study were to characterise the species, genotype, and subtype distribution of Cryptosporidium infections in Finland during 2021. This was carried out with 60 clinical samples from the hospital districts of Helsinki and Uusimaa, Vaasa, Kymenlaakso, and South Karelia as well as with Finnish Infectious Diseases Register (FIDR) data. Additionally, the study aimed to characterise the potential exposures related to Cryptosporidium chipmunk genotype I infections. Species identification as carried out with quantitative real-time polymerase chain reaction (qPCR) and 18S sequencing. Further typing was performed with gp60 subtyping. Over 70% of samples were identified as Cryptosporidium parvum and 20% as Cryptosporidium chipmunk genotype I, which has not been identified in Finland before. Only two cases of Cryptosporidium hominis were identified from patients who had reported travelling outside of Finland. The C. parvum subtype IIaA15G2R1 and the Cryptosporidium chipmunk genotype I subtype XIVaA20G2T1 were the top subtypes identified. Cryptosporidium chipmunk genotype I was more common in the Helsinki and Uusimaa district and interviewed cases did not have clear shared exposures, such as contact with wild rodents. In conclusion, C. parvum and Cryptosporidium chipmunk genotype I are the major causes of cryptosporidiosis in Finland.