(**A**) Percentage of fleas that developed complete proventricular blockage. The mean and SD are indicated. (**B**) Mortality rate of uninfected (open symbols) and infected (closed symbols) *O*. *montana* (red symbols) and *X*. *cheopis* (blue symbols). (**C**) Percentage of *O*. *montana* (red symbols) and *X*. *cheopis* (blue symbols) still infected 7 and 28 days after an infectious blood meal. (**D**) Mean bacterial load in infected *O*. *montana* (blue symbols) and *X*. *cheopis* (red symbols) immediately after the infectious blood meal (day 0) and at 7 and 28 days after infection. The cumulative results of three independent experiments (n = 99 to 113 fleas each) are shown in (**A, B**); the results of each of the three experiments are plotted in (**C, D**). **P* = 0.0003; ***P* < 0.0001 by Fisherâ€™s exact test (two-tailed).