Introduction

In Denmark, cryptosporidiosis is not under national surveillance. In December 2021, an outbreak of diarrhoea due to Cryptosporidium was identified among 30-40 employees (teachers and kitchen personnel) at a high school in Funen, Denmark. This report highlights the need for an active surveillance system that can facilitate the detection of clusters and prompt investigations of potential outbreaks.

Methods

Samples positive for Cryptosporidium at the local clinical microbiology department (Odense University Hospital) were sent to Statens Serum Institut for species identification and glycoprotein 60-based genotyping.

Results

Cryptosporidium parvum was identified in 13 samples; however, no less than three genotypes were identified (genotypes IIdA22G1c, IIdA25G1, and IIdA26G1b), none of which are commonly observed in Denmark. At least one of the genotypes was highly suspected to be linked to the outbreak (IIdA26G1b).

Over the next month, an outbreak of Cryptosporidium was suspected in the neighbouring administrative region of Zealand. However, the patients involved were geographically scattered. Gp60 data for these patients are pending and will reveal whether these two clusters can be linked.

Conclusions

Investigation into any links between the two outbreaks is ongoing. At present, no vehicle that could be responsible for the outbreak(s) has yet been identified.

In Denmark, all clinical microbiology laboratory data are available in the national Microbiological Database ‘MiBa’. With typing facilities in place at Statens Serum Institut, optimal conditions exist for national real-time monitoring of laboratory-confirmed cases of Cryptosporidium and outbreak investigations in Denmark.