Epidemiology and Infection

Genotyping of Cryptosporidium spp. isolated from human stool samples in Switzerland

R. FRETZ a1a3, P. SVOBODA a1, U. M. RYAN a2, R. C. A. THOMPSON a2, M. TANNER a3 and A. BAUMGARTNER a4c1
a1 Cantonal Laboratory Basel-Landschaft, 4410 Liestal, Switzerland
a2 WHO Collaborating Centre for the Molecular Epidemiology of Parasitic Infections and State Agricultural Biotechnology Centre, Division of Veterinary and Biomedical Sciences, Murdoch University, Western Australia 6150, Australia
a3 Swiss Tropical Institute, 4002 Basel, Switzerland
a4 Swiss Federal Office of Public Health, 3003 Bern, Switzerland

Article author query
fretz r   [PubMed][Google Scholar] 
svoboda p   [PubMed][Google Scholar] 
ryan u   [PubMed][Google Scholar] 
thompson r   [PubMed][Google Scholar] 
tanner m   [PubMed][Google Scholar] 
baumgartner a   [PubMed][Google Scholar] 


In a study to estimate the frequency of Cryptosporidium infections in Switzerland, stool samples from patients found to be positive for Cryptosporidium spp. by modified Ziehl–Neelson staining and fluorescence microscopy were used for genotyping experiments. With 9 of 12 samples, DNA extraction and subsequent genotyping was successful. All Cryptosporidium-isolates belonged to the bovine genotype. In one stool sample, two strains of Cryptosporidium were demonstrated, suggesting a mixed infection. In comparison with reference strains from calves, one of the isolates showed a full sequence identity and the other a similarity of 97·5%. The fact that only bovine genotypes were detected suggests, that cryptosporidiosis must primarily be considered as a zoonotic disease in Switzerland. This is in contrast to other countries, where the human genotype of C. parvum was shown to dominate the epidemiological situation. The results of our study are supported by the previous finding, that two of the analysed strains originated from patients who used to consume raw milk or raw cream, a known risk factor for cryptosporidiosis.

(Accepted March 18 2003)

c1 Swiss Federal Office of Public Health, Section of ‘Microbiology and Biotechnology’, 3003 Bern, Switzerland.