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

Background: 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. Findings:
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 beta-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. Conclusions: 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.