Molecular identification of zoonotic and livestock-specific Giardia-species in faecal samples of calves in Southern Germany

Giardia-infection in cattle is often subclinical or asymptomatic, but it can also cause diarrhoea. The livestock-specific species Giardia bovis is the most frequently observed in cattle, however, the two zoonotic species Giardia duodenalis and Giardia enterica have also been found. Therefore calves are thought to be of public health significance. The aim of this study was to obtain current data about the frequency of the different Giardia-species in calves in Southern Germany. Faecal samples of calves (diarrhoeic and healthy) in Southern Germany, diagnosed Giardia-positive by microscopy, were characterised by multi-locus PCR and sequencing.Of 152 microscopically Giardia-positive samples 110 (72.4%) were positive by PCR and successfully sequenced. G. bovis (Assemblage E) was detected in 101/110 (91.8%) PCR-positive samples, whilst G. duodenalis (Assemblage A) was detected in 8/110 (7.3%) samples and a mixed infection with G. duodenalis and G. bovis (Assemblage A+E) was identified in 1/110 (0.9%) samples. The sub-genotypes A1, E2 and E3 were identified with the β-giardin and the glutamate dehydrogenase genes. In the majority of diarrhoeic faecal samples a co-infection with Cryptosporidium spp. or Eimeria spp. was present, however, there were some in which G. bovis was the only protozoan pathogen found. The results suggest that there is potentially a risk for animal handlers as calves in Southern Germany are, at a low percentage, infected with the zoonotic species G. duodenalis. In addition, it was found that G. bovis was the only pathogen identified in some samples of diarrhoeic calves, indicating that this parasite may be a contributing factor to diarrhoea in calves.