Isolation of Helicobacter pylori from Sheep – Implications for Transmission to Humans.

OBJECTIVES: When and how Helicobacter pylori (H. pylori)
originally entered the human population as well as how the
infection is transmitted in different communities is unknown.
We previously showed that Sardinian shepherds had
almost a 100% prevalence of H. pylori and that the prevalence
was higher than that of their same-household siblings.
AIM: To examine whether H. pylori infection might be
transmitted from sheep.
METHODS: Milk and gastric tissue were cultured and analyzed
by PCR amplification using three sets of primers
Helicobacter genus–specific 16S rRNA and two sets of
primers specific for H. pylori vacA gene.
RESULTS: Helicobacter DNA was demonstrated in 60%
(38/63) of milk samples and in 30% (6/20) of sheep tissue
samples. H. pylori vacA gene was amplified in five of 38
milk samples, and in two of six sheep tissue samples respectively.
H. pylori were cultured from sheep milk and
tissue samples and confirmed as H. pylori on the basis of
colony morphology, positive biochemical reactions, and
negative Gram stain. Sequence analysis of 16S rRNA PCR
products from these isolates demonstrated 99% identity with
H. pylori.
CONCLUSIONS: Together, the presence of H. pylori in sheep
stomach in the absence of associated gastritis and recovery
of H. pylori from sheep milk and gastric tissue suggest that
sheep may be a natural host for H. pylori.