Table 2 Real-time PCR on ticks that were exposed to rickettsiae by feeding on Rickettsia rickettsii-infected horses

Unfed nymphs (fed as larvae on horses and molted to nymphs)

Unfed adults (fed as larvae on horses, fed as nymphs on rabbits, and molted to adults)

Unfed adults (fed as nymphs on horses and molted to adults)

Fed adults (fed as nymphs on horses and fed as adults on rabbits)^a

Fed adults (fed as adults on horses)^a

Group 1^b

1

2/90 (2.2 %)

2/56 (3.6 %)

0/83 (0)

12/51 (2.4 %)

16/280 (5.7 %)

2

0/70 (0)

0/29 (0)

0/99 (0)

Group 2^b

3

0/7 (0)

1/189 (0.5 %)

0/21 (0)

1/217 (0.5 %)

4

1/178 (0.6 %)

0/69 (0)

0/22 (0)

1/269 (0.4 %)

Total

2/90 (2.2 %)

1/185 (0.5 %)

2/56 (3.6 %)

1/411 (0.2 %)

12/123 (9.8 %)

18/865 (2.1 %)