Helicobacter pylori infection in shepherds, sheep and sheep-dogs

Objectives: Previous studies demonstrated a high prevalence of Helicobacter pylori infection
among shepherds, sheep, sheep raw milk and children having contact with sheep, suggesting a model of transmission
of infection at elevated frequency. The aim of this study was to examine whether H. pylori infection might
be present in sheep-dogs.
Material and Methods: Stool, serum, and wool were collected from sheep and sheep-dogs belonging to different
flocks chosen because the shepherds had documented (13C-UBT) H. pylori infection. H. pylori status in
the animals was evaluated using a homemade anti-H. pylori IgG enzyme-linked immunosorbent assay (ELISA)
for sheep and sheep-dogs. Stool samples from sheep and sheep-dogs were also analyzed using the stool antigen
test (HpSA) developed for humans. Results were expressed as optical density (OD450). PCR amplification was
performed using primers specific for H. pylori [cagA, vacA (s and m region), iceA, babA2] as well as primers
specific for Helicobacter species (16S rRNA) from the DNA extracted from sheep wool wash surrounding the
mammalian glands.
Results: 58 animals were studied (44 sheep, 8 lambs and 6 sheep-dogs). The H. pylori antigen test was positive in
82% (36/44) and in 100% of sheep and sheep-dogs stool samples, respectively. Lamb stool samples were weakly
positive. High anti H. pylori IgG serum levels were detected in all 6 sheep-dogs and in 42 of 44 sheep. Genomic
H. pylori and Helicobacter species DNA was not detected from any of the sheep wool samples collected.
Conclusions: Although cross-reactivity cannot be excluded, the presence of the H. pylori antigen in stools obtained
from sheep and from sheep-dogs, and the strong positivity for anti H. pylori IgG in both coupled with the
ability to isolate H. pylori from sheep milk and stomachs, suggest that interaction between species may enhance
the spread of bacteria in heavily contaminated settings.