Cryptosporidium infections in Denmark, 2010-2014.

INTRODUCTION The incidence of cryptosporidiosis in Denmark is unknown. Here, we present the number of cases detected in the 2010-2014 period along with data on species and subtypes. METHODS Complete national data retrieved from the Danish Microbiology Database and Statens Serum Institut (SSI) comprised test results on cryptosporidia detected by microscopy or polymerase chain reaction (PCR) between 1 January 2010 and 30 April 2014. Samples that tested positive at the SSI were submitted to species and subtype analysis by conventional PCR and sequencing of ribosomal and gp60 genes, respectively. RESULTS A total of 689 Cryptosporidium-positive stool samples were submitted by 387 patients. Limiting case episodes to two months (60 days), a total of 388 case episodes representing 387 patients were identified. Cryptosporidiosis was most common among infants and toddlers. Moreover, a peak in incidence was observed among younger adults aged 23-24 years. In 43 Cryptosporidium-positive faecal samples, identification was performed to species and subtype level. Cryptosporidium parvum was found in 34 samples, C. hominis in eight, and C. meleagridis in one sample; C. parvum subtypes IIaA15G2R1 (n = 10) and IIaA16G3R1 (n = 5) were predominating. CONCLUSION Cryptosporidia are a significant cause of diarrhoea in Denmark. Outbreaks may not be detected due to continued use of diagnostic tests of limited sensitivity and due to lack of surveillance. With molecular methods now being introduced in many Danish laboratories, we propose establishing national surveillance of cryptosporidiosis. FUNDING not relevant. TRIAL REGISTRATION not relevant.