Toxoplasma infection in intermediate host species closely associates
with inflammation. This association has led to suggestions that the
behavioural changes associated with infection may be indirectly driven
by the resulting sustained inflammation rather than a direct behavioural
manipulation by the parasite. If this is correct, sustained inflammation
in chronically infected rodents should present as widespread changes in
the gastrointestinal microbiota due to the dependency between the
composition of these microbiota and sustained inflammation. We conducted
a randomized controlled experiment in rats that were assigned to a
Toxoplasma-treatment, placebo-treatment or negative control group. We
sacrificed rats during the chronic phase of infection, collected their
cecal stool samples and sequenced the V3-V4 region of the 16S rRNA gene
to characterise the bacterial community in these samples. Toxoplasma
infection did not induce widespread changes in the bacterial community
composition of the gastrointestinal tract of rats. Rather, we found sex
differences in the bacterial community composition and only minor
changes in Toxoplasma infected rats. We conclude that it is unlikely
that sustained inflammation is the mechanism driving the highly specific
behavioural changes observed in Toxoplasma-positive rats.