Previously we have described the transmission of malaria by the oral r
oute in a murine model. Due to the similarities between Plasmodium and
Babesia, we tried to reproduce oral transmission in parasites of the
latter genus by ingestion of infected blood and by cannibalism. In the
first case, experimental mice were inoculated orally with 20, 50, or
100 mu l of Babesia microti-infected blood, and in the second, each fa
sted experimental mouse was offered the corpse of an infected mouse se
rving as the bait inoculum. B. microti infection was acquired by 3.7%
of all experimental animals orally inoculated with infected blood and
by 15.1% of all mice inoculated by cannibalism. The approximate period
of prepatency ran from 2 to 4 weeks. No control mouse acquired the in
fection. This represents the first time that oral transmission of babe
siosis has been described. This kind of transmission may be present in
nature. Babesiosis may be acquired and maintained in nature in the ab
sence of ticks.