Cryptosporidium subtype IfA12G1R5 predominated in Spain in 2023

Researchers compared published molecular data with clinical samples collected in Spain before and after the COVID-19 pandemic. The analysis included 389 prepandemic samples and 126 postpandemic samples collected in 2023, alongside historical data from 806 characterized isolates. Samples were tested and genotyped at the gp60 marker; the analysis focused on C. hominis and C. parvum.

Before the pandemic, C. hominis predominated, with subtype IbA10G2 accounting for most isolates. In the 2023 samples, C. hominis made up 96.0% of infections. Subtype IfA12G1R5 accounted for 67.5% of cases, while IbA10G2 fell to 1.6% in the comparison of 2013–2023 reference-laboratory data. C. parvum represented 4.0% of the 2023 samples.

The authors interpret the findings as evidence of a major subtype shift and sustained community transmission of IfA12G1R5, consistent with findings from Spanish outbreak investigations. They suggest the lineage’s reported high transmissibility may have contributed to its spread, but the mechanisms remain unclear. The study is limited by its observational design, geographic and sampling coverage, and the use of molecular subtype data to infer transmission; the journal notes that this early-release version is not final.