Molecular epidemiology with subtype analysis of Cryptosporidium in calves in Belgium

The prevalence of Cryptosporidium in calves younger than 10 weeks was estimated in a cross-sectional epidemiological study on 100 dairy (n=499) and 50 beef (n=333) farms in East Flanders (Belgium), using a previously evaluated immunofluorescence assay (Merifluor). The calf prevalence was 37% (95% Probability Interval (PI): 7-70%) in dairy calves and 12% (95% PI: 1-30%) in beef calves. To elucidate the genetic diversity, the Cryptosporidium 18S ribosomal DNA and the 70 kDa heat shock protein gene were targeted. In the majority of the samples C. parvum was present, although C. bovis was also identified, all but one in calves older than 1 month. The porcine-specific C. suis was identified in 1 beef calf. Subtyping of C. parvum positive isolates by sequence analysis of the 60 kDa glycoprotein gene indicated the presence of 4 allele IIa subtypes, along with 1 subtype IIdA22G1. The subtype IIaA15G2R1 was most prevalent, next to subtype IIaA13G2R1 and IIaA16G2R1, and a new subtype IIaA14G2R1. The results of the present study indicate a high prevalence of Cryptosporidium infections in calves in Belgium and confirm that these calves should be considered as a potential zoonotic reservoir for human infections.