Anaplasma marginale strain-specific bacteremia during tick acquisition feeding

StrainNo. of bacteria (mean ± SE)/ml blood during 7-day feed
Single-strain-infected animalsSuperinfected animalsa
Vaccine106.3 ± 0.4106.8 ± 0.6107.2 ± 0.05107.1 ± 0.4
St. Maries107.0 ± 0.1105.2 ± 0.2105.3 ± 0.05106.0 ± 0.05
  • a Strain superinfections were established by first infecting animals with the vaccine strain, followed by tick-borne transmission of the St. Maries strain. There were significantly higher levels of the vaccine strain than of the St. Maries strain in the superinfected animals during the 7-day tick acquisition feeding period (P = 0.02; analysis of variance for data with equal variances, as determined using the modified Levene equal-variance test).