Table 3

Infection within Dermacentor andersoni ticks prior to and following tick passage

CharacteristicValue for ticksa
Calf V3 given vaccine strainCalf TP1 given tick passage strain
TT3TT4TP2TP3
Midgut infection rate, % (no. ticks infected/total no. of ticks)90 (45/50)90 (45/50)76 (38/50)78 (39/50)
Bacteria per midgut, mean no. (±SEM)104.3 (±100.82)104.3 (±100.69)103.9 (±100.68)104.2 (±100.8)
Salivary gland infection rate, % (no. ticks infected/total no. of ticks)80 (40/50)82 (41/50)78 (39/50)84 (42/50)
Bacteria per salivary gland, mean no. (±SEM)105.9 (±100.9)105.8 (±100.8)105.8 (±100.9)105.7 (±100.8)
Saliva containing Anaplasma, % (no. ticks infected/total no. of ticks)18 (9/50)20 (10/50)8 (4/50)20 (10/50)
Bacteria per μl of saliva, mean no. (±SEM)102.7 (±100.7)102.3 (±100.5)102.7 (±100.4)101.8 (±100.4)
  • a The values for ticks from calves V3 and TP1 exposed to a vaccine strain or tick passage strain. Calves V3 and TP1 were acquisition-fed calves. Calves TT3, TT4, TP2, and TP3 were transmission-fed calves. Calves TT3 and TP2 were exposed to 500 ticks, while calves TT4 and TP3 were exposed to 100 ticks.